Colorectal Surgery E-Book
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Colorectal Surgery E-Book


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Colorectal Surgery equips you to overcome the clinical challenges you face in this area of surgery. Written for the general surgeon who is called upon to manage diseases and disorders of the large bowel, rectum, and anus, this reference provides advanced, expert guidance on how to avoid complications and achieve the most successful results.
  • Visualize relevant anatomy and techniques more easily with high-quality, full-color line drawings and clinical photos throughout.
  • Zero in on the information you need with key points boxes in every chapter that provide a quick overview of the topic at hand.
  • Get practical, hands-on advice on managing the diseases and disorders you’re most likely to encounter.
  • Learn from acknowledged leaders in the field who excel in both academic and clinical areas.


United States of America
Surgical incision
Endometriosis of ovary
Myocardial infarction
Stoma (disambiguation)
Sexually transmitted disease
Octreotide scan
Mobility aids
Colorectal polyp
Surgical suture
Incision and drainage
Perforated ulcer
Pruritus ani
Anal sphincterotomy
Anorectal abscess
Bowel resection
Ischemic colitis
Endometrial ablation
Blood in stool
Stoma (medicine)
Toxic megacolon
Primary sclerosing cholangitis
Medical Center
Trauma (medicine)
Rectal prolapse
Inflammatory bowel disease
Abdominal pain
Hidradenitis suppurativa
Physician assistant
Pain management
Irritant diaper dermatitis
Sarcoptes scabiei
Pilonidal cyst
Bowel obstruction
Health care
Complete blood count
Irritable bowel syndrome
Pulmonary embolism
Colorectal cancer
Internal medicine
Genital wart
Fecal incontinence
Non-Hodgkin lymphoma
Ulcerative colitis
Crohn's disease
Large intestine
X-ray computed tomography
Radiation therapy
Positron emission tomography
Magnetic resonance imaging
Laparoscopic surgery
General surgery
Chlamydia infection
Abdominal surgery


Publié par
Date de parution 27 septembre 2012
Nombre de lectures 3
EAN13 9781455737703
Langue English
Poids de l'ouvrage 4 Mo

Informations légales : prix de location à la page 0,0536€. Cette information est donnée uniquement à titre indicatif conformément à la législation en vigueur.


Colorectal Surgery

H. Randolph Bailey, MD
Chief, Division of Colon and Rectal Surgery, Deputy Chief, Department of Surgery, Clinical Professor of Surgery, Weill Cornell Medical College, The Methodist Hospital, Houston, Texas

Richard P. Billingham, MD
Clinical Professor, Department of Surgery, University of Washington, Swedish Medical Center, Seattle, Washington

Michael J. Stamos, MD
John E. Connolly Chair and Professor of Surgery, University of California, Irvine Medical Center, Orange, California

Michael J. Snyder, MD
Director, Residency in Colon and Rectal Surgery, Clinical Associate Professor of Surgery, The University of Texas Medical School at Houston, Houston, Texas

Table of Contents
Cover image
Title page
section I: General
Chapter 1: Anatomy and Physiology
The Bottom Line
Anatomy of the Colon and Rectum
Blood Supply of the Colon and Rectum
Chapter 2: Diagnostic Evaluations
Abdominal Pain
Rectal Bleeding
Anal Pain
Perianal Itching
Perianal Mass
Seepage and Incontinence
External Inspection and Digital Rectal Examination
Rigid Proctosigmoidoscopy
Flexible Sigmoidoscopy
Computed Tomographic Colography
Barium Enema
Water-Soluble Contrast Media Studies
Stool Studies
Evaluation of Small Intestine
Small Bowel Imaging
Capsule Endoscopy
Double Balloon Endoscopy
Radionuclide Studies
Anorectal Testing
Colonic Transit Studies
Endorectal Ultrasound
Serologic Biomarkers for Inflammatory Bowel Disease
Chapter 3: Preoperative Management
Overall Preoperative Management Issues
Continuing or Holding Medications
Choice of Anesthetic
Preoperative Management of Patients with Known Diseases
Patients With Pulmonary Hypertension
Prophylaxis Against Common Problems
Preoperative Clinic
Chapter 4: Postoperative Management
Postoperative Physiology
Postoperative Management
Gastrointestinal Tract Function and Enteral Feeding
Early Ambulation
Deep Vein Thrombosis Prophylaxis
Prevention of Infection
Pain Management after Colorectal Surgery
Postoperative Management of Preoperative Medications
Anorectal Surgery
Postoperative Clinical Pathways
Chapter 5: General Postoperative Complications and How to Prevent Them
Wound and Fascial Dehiscence
Anastomotic Leak
Postoperative Factors
Postoperative Pneumonia
Deep Vein Thrombosis and Pulmonary Embolism
section II: Anorectal
Chapter 6: Hemorrhoids
Anatomy and Physiology
Differential Diagnosis and Diagnosis
Nonoperative Treatment
Operative Treatment
Special Circumstances
Chapter 7: Anal Fissure
Presentation and Diagnosis
Treatment—Nonoperative Therapy
Operative Management
Pitfalls In Management
Tips and Tricks
When to Refer
Chapter 8: Abscess and Fistula
Chapter 9: Complex Colorectal Fistulas
Enterocutaneous Fistula
Colocutaneous Fistula
Colovaginal Fistula
Rectovaginal Fistula
Colovesical Fistula
Rectourethral Fistula
Chapter 10: Pilonidal Disease and Hidradenitis Suppurativa
Pilonidal Disease
Hidradenitis Suppurativa
Chapter 11: Anogenital Condyloma and Other Sexually Transmitted Diseases
Approach to the Patient with a Presumed Sexually Transmitted Disease
Bacterial Infections
Viral Infections
section III: Colorectal Malignancy
Chapter 12: Screening for Colorectal Cancer
Who and When to Screen
Stool Tests
Structural Tests
Barriers to Screening
Chapter 13: Polyps
Polyp Detection and Management
Types of Polyps
Polyposis and Other Syndromes
Other Syndromes
Chapter 14: Colon Cancer Evaluation and Staging
The Bottom Line
Clinical Presentation
Staging and Prognostic Factors
Clinical Prognostic Factors
Histologic, Biochemical, and Genetic Factors
Lymphovascular Invasion/Perineural Invasion
Patterns of Spread
Practice Parameters for Detection of Colorectal Neoplasms as Defined by the Standards Committee, the American Society of Colon and Rectal Surgeons*
Chapter 15: Surgical Management of Colon Cancer
Preoperative Evaluation
Bowel Preparation
Surgical Preparation
Operative Technique
Specific Management Situations
Chapter 16: Management of Rectal Cancer
The Office Visit
Staging and Imaging
Neoadjuvant Chemotherapy and Radiation
Surgical Management
Need for Postoperative Chemotherapy
Metastatic Disease
Chapter 17: Colorectal Cancer: Adjuvant Therapy and Surveillance
Adjuvant Therapy for Colon Cancer
Overview of Chemotherapeutic Agents
Recommendations for Adjuvant Therapy by Colon Cancer Stage
Adjuvant Therapy for Rectal Cancer
Colorectal Cancer Surveillance
Rationale for Postoperative Surveillance
Diagnostic Modalities
Surveillance Schedules: Is Intensive Follow-Up Beneficial?
Current Surveillance Guidelines
Chapter 18: Treatment of Metastatic or Recurrent Colorectal Cancer
Natural History of Disease
Assessment of Resection
Functional Liver Remnant
Local Ablative Therapies
Extrahepatic Disease
Chapter 19: Anal Malignancies
The Bottom Line
Anatomy and Histology
Clinical Evaluation
Epidemiology and Risk Factors
Anal Margin Cancer
Anal Canal Malignancies
Uncommon Anal Canal Neoplasms
Chapter 20: Miscellaneous Neoplasms
Carcinoid Tumors
Gastrointestinal Stromal Tumors
Gastrointestinal Lymphoma
Colorectal and Anal Complications of Leukemia
section IV: Infl ammatory Conditions
Chapter 21: Inflammatory Bowel Disease
Epidemiology of Inflammatory Bowel Disease
Clinical History and Presentation
Diagnosis and Assessment
Medical Management of Inflammatory Bowel Disease
Inflammatory Bowel Disease Surgery: The Medical Perspective
Chapter 22: Surgical Management of Ulcerative Colitis
The Bottom Line
Indications for Surgery
Emergency Surgery
Elective Surgery
Functional Outcomes
Biologics and Ileal Pouch Anal Anastomosis
Continent Ileostomy
Chapter 23: Surgery for Crohn Disease
Natural History
Operative Indications
Operative Considerations
Operative Options
Disease Locations and Specific Operative Management
Prophylaxis against Recurrent Disease
Chapter 24: Diverticulitis
Pathophysiology of Diverticulitis
Acute Uncomplicated Diverticulitis
Acute Complicated Diverticulitis: Perforation and Abscess
Chronic Complicated Diverticulitis: Stricture and Fistula
Emerging Techniques
Diverticular Hemorrhage
Common Complications of Operation
Uncommon Complications of Operation
Chapter 25: Lower Gastrointestinal Hemorrhage
Initial Management
Diagnostic Evaluation
Radiologic Examinations
Obscure Gastrointestinal Bleeding
Operative Intervention
Chapter 26: Radiation, Ischemic, and Infectious Colitides
The Bottom Line
Radiation Colitis
Ischemic Colitis
Infectious Colitis
Chapter 27: Large and Small Bowel Obstruction
Presentation, Diagnosis, and Initial Treatment
Bowel Obstruction after Previous Laparoscopic Surgery
Other Treatment Considerations
Operative Technical Points
Prevention of Adhesion Formation
Prevention of Hernia Formation
Large Bowel Obstruction
Chapter 28: Intestinal Stomas and Their Complications
The Bottom Line
Preoperative Counseling and Stoma Sitting
End Ileostomy
Loop Ileostomy
End Colostomy
Mucous Fistula
Stoma Closure
section V: Functional Problems
Chapter 29: Incontinence and Rectocele
The Bottom Line
Chapter 30: Rectal Prolapse
The Bottom Line
Clinical Findings
Physical Examination
Operative Management
Choice of Operation
Recurrent Rectal Prolapse
Chapter 31: Pruritus Ani and Other Perianal Dermatoses
section VI: Miscellaneous
Chapter 32: Colon and Rectal Trauma
Mechanism of Injury
Injury Grades
Operative Technique
Rectal Injuries
Antibiotic Use
Closure of Colostomy
Foreign Bodies of the Rectum
Chapter 33: Uncommon Disorders
The Bottom Line
Presacral Tumors

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COLORECTAL SURGERY ISBN: 978-1-4377-1724-2
Copyright © 2013 by Saunders, an imprint of Elsevier Inc.
Chapter 24: “Diverticulitis” by Daniel Herzig: Daniel Herzig retains copyright to his original figures.
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Library of Congress Cataloging-in-Publication Data
Colorectal surgery / H. Randolph Bailey … [et al.].
  p. ; cm.
 Includes bibliographical references and index.
 ISBN 978-1-4377-1724-2 (hardcover : alk. paper)
 I. Bailey, H. Randolph.
 [DNLM: 1. Colonic Diseases–surgery. 2. Colon–surgery. 3. Digestive System Surgical Procedures–methods. 4. Rectal Diseases–surgery. 5. Rectum–surgery.  WI 650]
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Printed in China.
Last digit is the print number: 9 8 7 6 5 4 3 2 1

Maher A. Abbas, MD
Assistant Professor of Surgery Department of Surgery University of California, Los Angeles School of Medicine Chair Center for Minimally Invasive Surgery Chief Colon and Rectal Surgery Kaiser Permanente Medical Center Los Angeles, California
Complex Colorectal Fistulas

Abier Abdelnaby, MD
Assistant Professor of Surgery University of Texas Southwestern Medical Center Dallas, Texas
Anatomy and Physiology

Armen Aboulian, MD
Department of Surgery Kaiser Permanente Medical Center Woodland Hills, California
Diagnostic Evaluations

Jeffrey B. Albright, MD
Staff Surgeon Birmingham Surgical Brookwood Medical Center Birmingham, Alabama
Radiation, Ischemic, and Infectious Colitides

Farshid Araghizadeh, MD
Associate Professor of Surgery Chief Section of Colon and Rectal Surgery University of Texas Southwestern Medical Center Dallas, Texas
Anatomy and Physiology

Amir L. Bastawrous, MD
Program Director Colon and Rectal Surgery Department of Surgery Swedish Medical Center Seattle, Washington

Jennifer Beaty, MD
Assistant Professor of Surgery Creighton University Assistant Professor of Surgery University of Nebraska Medical Center Omaha, Nebraska
Radiation, Ischemic, and Infectious Colitides

Brian S. Buchberg
Department of Surgery University of California, Irvine Medical Center Orange, California
Surgical Management of Colon Cancer

Joseph R. Cali, JR., MD
Clinical Instructor of Surgery University of Texas Health Science Center at Houston Houston, Texas
Uncommon Disorders

Bradley J. Champagne, MD
Division of Colorectal Surgery Case Medical Center Cleveland, Ohio
Management of Rectal Cancer

Diana Cheng-Robles
Department of General Surgery Antelope Valley Kaiser Permanente Medical Center Lancaster, California
Colon Cancer Evaluation and Staging

Robert R. Cima, MD, MA
Associate Professor of Surgery Division of Colon and Rectal Surgery Mayo Clinic Rochester, Minnesota
Surgical Management of Ulcerative Colitis

Bard C. Cosman, MD, MPH
Chief Halasz General Surgery Section Veterans Affairs San Diego Healthcare System Professor of Clinical Surgery Department of Surgery University of California, San Diego School of Medicine San Diego, California
Preoperative Management

Todd W. Costantini, MD
Department of Surgery University of California, San Diego School of Medicine San Diego, California
Preoperative Management

David A. Etzioni, MD, MSHS
Associate Professor Department of Surgery Mayo Clinic Arizona Phoenix, Arizona
Incontinence and Rectocele

Gregory Fitzharris, MD
Colorectal Staff Surgeon Sentara Surgery Specialists Sentara Careplex Hospital Hampton, Virginia
General Postoperative Complications and How to Prevent Them

Debra Holly Ford, MD
Associate Professor and Vice-Chairman Head Section of Colon and Rectal Surgery Department of Surgery Howard University College of Medicine Washington, DC
Pilonidal Disease and Hidradenitis Suppurativa

Dhruvil P. Gandhi, MD
Clinical Instructor Department of Colorectal Surgery University of California, Irvine Medical Center Orange, California

Nipa Gandhi, MD
Associate Clinical Professor of Surgery Columbia University Colon and Rectal Surgery St. Luke’s-Roosevelt Hospital New York, New York
Anogenital Condyloma and Other Sexually Transmitted Diseases

Dan Geisler, MD
Co-Director Inflammatory Bowel Disease Clinic The Ohio State University Wexner Medical Center Columbus, Ohio
Intestinal Stomas and Their Complications

Ed Glennon, MD
University of Pittsburgh Medical Center Hamot Erie, Pennsylvania
Intestinal Stomas and Their Complications

Lester Gottesman, MD
Associate Clinical Professor of Surgery Columbia University Division of Colon and Rectal Surgery St. Luke’s-Roosevelt Hospital New York, New York
Anogenital Condyloma and Other Sexually Transmitted Diseases

Leander M. Grimm, JR., MD
Administrative Chief Resident Department of General Surgery University of Alabama at Birmingham Birmingham, Alabama
Lower Gastrointestinal Hemorrhage

Kerry L. Hammond, MD
Assistant Professor Colon and Rectal Surgery Department of Surgery Medical University of South Carolina Charleston, South Carolina
Colorectal Cancer: Adjuvant Therapy and Surveillance

Jacques Heppell, MD
Department of Surgery Mayo Clinic Arizona Phoenix, Arizona
Incontinence and Rectocele

Daniel Herzig, MD
Assistant Professor Department of Surgery Oregon Health & Science University Portland, Oregon

John B. Holcomb, MD
Jack H. Mayfield Chair in Surgery Professor and Vice-Chair Department of Surgery Chief Division of Acute Care Surgery Director Center for Translational Injury Research Department of Surgery University of Texas Medical School at Houston Houston, Texas
Colon and Rectal Trauma

David K. Imagawa, MD, PhD
Professor of Surgery Department of Surgery University of California, Irvine Medical Center Orange, California
Treatment of Metastatic or Recurrent Colorectal Cancer

Eric K. Johnson, MD
Colorectal Surgery Madigan Army Medical Center Tacoma, Washington
Anal Fissure

Cindy Kin, MD
Department of Surgery Stanford Hospital and Clinics Stanford, California
Anal Malignancies

Ravin R. Kumar, MD
Chief Division of Colon and Rectal Surgery Department of Surgery Harbor-University of California Los Angeles Medical Center Torrance, California Associate Professor in Surgery Department of Surgery University of California, Los Angeles School of Medicine Los Angeles, California
Diagnostic Evaluations

Phillip A. Letourneau, MD
Resident Physician Department of Surgery University of Texas Medical School at Houston Houston, Texas
Colon and Rectal Trauma

Khaled Madbouly, MD, MS, PhD
Assistant Professor Department of Surgery Section of Colorectal Surgery University of Alexandria Alexandria, Egypt
Complex Colorectal Fistulas

Justin A. Maykel, MD
Chief Division of Colon and Rectal Surgery Department of Surgery University of Massachusetts Memorial Medical Center Assistant Professor of Surgery University of Massachusetts Medical School Worcester, Massachusetts
Postoperative Management

James Mccormick, DO
Vice-Chair Department of Surgery Western Pennsylvania Hospital Assistant Professor Department of Surgery Temple University School of Medicine Pittsburgh, Pennsylvania
Large and Small Bowel Obstruction

Steven D. Mills, MD
Department of Surgery University of California, Irvine Medical Center Orange, California
Surgical Management of Colon Cancer

Melanie S. Morris, MD
Assistant Professor Department of Surgery University of Alabama at Birmingham Birmingham, Alabama
Lower Gastrointestinal Hemorrhage

Zuri Murrell, MD
Attending Physician Division of Colorectal Surgery Cedars-Sinai Medical Center Los Angeles, Califronia
Colon Cancer Evaluation and Staging

Nandini Nagaraj, MD
Gastroenterology Associates of North Texas Fort Worth, Texas
Inflammatory Bowel Disease

Jeffery Nelson, MD
Chief Colon and Rectal Surgery Department of Surgery Walter Reed Army Medical Center Washington, DC
Abscess and Fistula

Reetesh Pai, MD
Assistant Professor Department of Pathology Stanford University School of Medicine Stanford, California
Miscellaneous Neoplasms

Mark J. Pidala, MD
Clinical Assistant Instructor Colon and Rectal Surgery Department of Surgery University of Texas Health Science Center at Houston Staff Colon and Rectal Surgeon Department of Surgery Houston Northwest Medical Center Houston, Texas
Rectal Prolapse

Darren Pollock, MD
Staff Surgeon Swedish Colon and Rectal Clinic Swedish Cancer Institute Swedish Medical Center Seattle, Washington
Pruritus Ani and Other Perianal Dermatoses

Rana Pullatt, MD
Assistant Professor Gastrointestinal and Laparoscopic Surgery Department of Surgery Medical University of South Carolina Charleston, South Carolina
Colorectal Cancer: Adjuvant Therapy and Surveillance

Nalini Raju, MD, MPH
Assistant Professor Department of Colorectal Surgery Stanford University School of Medicine Stanford, California
Miscellaneous Neoplasms

M. Parker Roberts, III, MD
Department of Surgery Maine Medical Center Portland, Maine Clinical Assistant Professor Department of Surgery University of Vermont Burlington, Vermont
Lower Gastrointestinal Hemorrhage

Daniel C. Rossi, DO
Associate Colorectal Surgery Department of Surgery Geisinger Health System Wilkes-Barre, Pennsylvania

Joseph Sellin, MD
Chief of Gastroenterology Ben Taub General Hospital Director Gastroenterology Fellowship Professor of Medicine Baylor College of Medicine Houston, Texas
Inflammatory Bowel Disease

Andrew Shelton, MD
Department of Surgery Stanford Hospital and Clinics Stanford, California
Anal Malignancies

Clifford L. Simmang, MD, MS
Texas Colon and Rectal Surgeons Dallas, Texas
Large and Small Bowel Obstruction

Scott R. Steele, MD
Chief Colon and Rectal Surgery Madigan Army Medical Center Tacoma, Washington
Anal Fissure

Scott A. Strong, MD
Staff Colorectal Surgery Cleveland Clinic Cleveland, Ohio
Surgery for Crohn Disease

Paul R. Sturrock, MD
Assistant Professor of Surgery University of Massachusetts Medical School Worcester, Massachusetts
Postoperative Management

Mark Lane Welton, MD, MHCM
Interim Medical Director Clinical Cancer Center Professor and Chief Colorectal Surgery Department of Surgery Stanford University School of Medicine Stanford, California
Miscellaneous Neoplasms

Charles B. Whitlow, MD
Residency Program Director Department of Colon and Rectal Surgery Ochsner Medical Center New Orleans, Louisiana
Screening for Colorectal Cancer

Maki Yamamoto, MD
Department of Surgery University of California, Irvine Medical Center Orange, California
Treatment of Metastatic or Recurrent Colorectal Cancer
More than 2 years ago, I was contacted by an acquisitions editor at Elsevier, about the possibility of producing a new textbook on colon and rectal surgery. Initially, my response was that excellent books were already available. Further discussion of the proposal to create a reference book that was more focused on the general surgeon and surgical residents made me reconsider. The final selling point was the possibility of a book heavily illustrated with color images, drawings, radiographic images, and photographs.
After agreeing to further consider the project, I clearly needed able and willing assistance. I was able to recruit my first three choices to work with me on editing the book. Richard Billingham, from Seattle, Washington; Michael Stamos, from Orange County, California; and Mike Snyder, one of my partners in Houston, not only agreed but also worked tirelessly to complete the book.

H. Randolph Bailey, MD
There are multiple excellent encyclopedic offerings on colon and rectal surgery. Our goal was not to create another tome, but to put together something that general surgical residents could easily read during their residency (with the added feature of online access to the full text from all computers and mobile devices). General surgeons in practice treat the majority of colorectal disease in the United States, and we wanted to give them guidance and focus in the management of many of the problems that they encounter.
Our 33 chapters were written by 33 different authors. Their promptness in submitting their manuscripts and willingness to respond to our suggestions and requests for changes were critical to the successful completion of the manuscript. The staff at Elsevier, in particular, Judith Fletcher, Joanie Milnes, and Jessica Becher, showed great patience and understanding as they shepherded us through this project. We cannot thank the chapter authors enough for putting up with our demands for a quality product. We think we have succeeded.
Finally, the four editors could not have done this without the support and patience of our wives or significant others, Kelly Bailey, Judy Folks, Bridget Stamos, and Elizabeth Snyder. We stole many hours that we would have otherwise devoted to them while we worked nights and weekends on this project. Thanks to them from the bottoms of our hearts.

H. Randolph Bailey, MD

Richard P. Billingham, MD

Michael J. Stamos, MD

Michael J. Snyder, MD
I am honored to comment on the new textbook, Colorectal Surgery , by H. Randolph Bailey, Richard P. Billingham, Michael J. Stamos, and Michael J. Snyder. The authors have shown great leadership in creating a book that is useful to the general surgeon as well as to colorectal surgeons by providing a common vehicle to educate all involved in colorectal surgery. The specialization of surgery is essential in particular for the most complex cases. Common knowledge shared between the general surgeon and colorectal surgeon protects the patient, provides broader access for common problems, and highlights the importance of a specialty for complex problems. The editors and authors have aimed this book at general surgeons to best support the education of all who care for patients with colorectal disease. The text is enriched by the extensive use of illustrations.
The expertise represented by Drs. Bailey, Billingham, Stamos, and Snyder exemplifies the best of colorectal surgery. They each have active practices with far-reaching expertise. All have been essential in leading this specialty and defining board certification criteria. Their backgrounds shape the educational choices and perspectives, enhancing the value of this book to the practicing surgeon.
Colorectal Surgery is divided into six sections covering general topics, anorectal conditions, colorectal malignancy, inflammatory conditions, functional problems, and miscellaneous conditions (e.g., trauma). The editors have selected authors with broad, pragmatic expertise. The chapters are clearly written with straightforward text, useful references, excellent tables, and simple figures. All focus on patient care.
This book will be read widely by general surgeons, colorectal surgeons, residents and trainees, and referring physicians. It has filled a great need. The editors should be very proud. This will be a standard book for all surgeons caring for the spectrum of colorectal disease.

David B. Hoyt, MD
Executive Director American College of Surgeons
section I
chapter 1 Anatomy and Physiology

Farshid Araghizadeh, Abier Abdelnaby

The Bottom Line

• The colon is the last part of the digestive system in most vertebrates and bears distinct characteristics: the presence of the taeniae coli, the haustral sacculations, and the appendices epiploicae.
• The rectum serves as a reservoir and is characterized by the absence of taeniae coli, appendices epiploicae, or a well-defined mesentery. The term mesorectum is a misnomer and applies to the perirectal areolar tissue, which contains the lymphatic drainage system and blood supply. The rectosacral fascia and Denonvilliers fascia are both important landmarks during complete rectal mobilization.
• The dentate line of the anal canal serves as an important landmark to help differentiate between the type of epithelium above and below it (columnar vs squamous) as well as the lymphatic drainage pattern above and below it.
• The external anal sphincter is comprised of three parts: subcutaneous, superficial, and deep. The levator ani muscle forms the bulk of the pelvic floor.
• Colonic blood supply is from the superior mesenteric artery and inferior mesenteric artery (IMA), whereas the blood supply to the rectum is from the IMA as well as branches of the internal iliac arteries. The venous drainage pattern mirrors the arterial blood supply, with the rectum having a dual drainage system. The colon and rectum are innervated by the parasympathetic as well as sympathetic nervous systems.
• The primary physiologic functions of the colon are absorption of water and electrolytes, further metabolism of ingested foods by microfloral metabolism, storage of semisolid matter, and propulsion of fecal material towards the rectum. The principal energy source for colonocytes is short chain fatty acids (SCFAs). Mass movements occur as a result of strong, propulsive, and migrating contractile forces of the smooth muscle of the large intestine and are responsible for the distal propulsion of fecal material and forward movement of luminal contents.
• The process of defecation is regulated by a complex set of anatomic and physiologic factors.
The large intestine begins at the ileocecal valve and terminates at the anus. It is approximately 150 cm in length, which corresponds to one-quarter the length of the small intestine. The principal functions of the colon and rectum are water and electrolyte absorption, digestion of residual carbohydrates and protein, transit and storage of stool, and control of defecation. These functions are accomplished through a series of complex anatomic and physiologic relationships.

Anatomy of the Colon and Rectum
The colon is a capacious tube that frames the loops of the small intestine within the abdominal cavity. It is the last part of the digestive system in most vertebrates and possesses distinct characteristics: the taeniae coli, the haustra, and the appendices epiploicae. The taeniae coli, readily visible on inspection, are three bands of outer longitudinal muscle traveling along the colon from the base of the appendix to the rectosigmoid junction, where they merge and continue through the entire length of the rectum. The haustral sacculations are outpouchings of bowel wall between the taeniae; they are caused by the relative shortness of the taeniae, which is approximately one-sixth shorter than the length of the colon. 1 The appendices epiploicae are small appendages of fat that protrude from the serosal aspect of the colon.

The cecum, which is a broad sac-like pouch, is the first part of the large intestine, measuring 5 to 7 cm in length. The ileum, which is the last part of the small intestine, terminates into the posteromedial aspect of the cecum. 1 Approximately 2.5 cm inferior to the ileocecal junction, the vermiform appendix opens into its medial aspect. The cecum is located in the right lower quadrant, where it lies in the iliac fossa, inferior to the ascending colon. The cecum may be entirely, or at least in its lower half, invested with peritoneum, and can be quite mobile. It does not have a mesentery. 2 Peritoneal folds frequently attach the cecum to the iliac fossa laterally and medially. These folds create a small cul-de-sac, called the retrocolic recess ( Fig. 1-1 ). The superior and inferior ileocecal ligaments maintain the angulation between the terminal ileum and cecum and contribute to the formation of the ileocecal valve. These structures are important in the prevention of reflux of chyme back into the terminal ileum, up to colonic pressures of 80 mm Hg 3 ( Fig. 1-2 ).

Figure 1-1 Retrocolic recess. This area is visualized after mobilization of the cecum cephalad and to the left.

Figure 1-2 The ileocecal valve as seen on colonoscopy.

The vermiform appendix is a narrow worm-shaped tube that joins the cecum about 2 to 3 cm below the ileocecal junction. Its length varies from 2 to 20 cm, and it is approximately 5 mm in diameter. 1 The appendix has its own short triangular mesentery called the mesoappendix, which suspends it from the posterior leaflet of the terminal ileal mesentery. The position of the appendix is variable, even at different times in the same individual, but it is usually retrocecal (65%). It can also be pelvic (31%), retrocolic (0.3%), subcecal (2.3%), preileal (1%), or retroileal (0.4%). 1, 3 The three taeniae coli of the cecum converge at the base of the appendix, forming a complete outer longitudinal muscle coat.

Ascending Colon
The ascending colon, which extends from the ileocecal junction to the hepatic flexure, varies in length from 12 to 20 cm. 2 It is a retroperitoneal structure, covered by peritoneum anteriorly and on both sides, attaching it to the posterior abdominal wall. In addition, fragile adhesions between the right abdominal wall and its anterior aspect, known as Jackson’s membrane, may be present. 1, 4 Below the right lobe of the liver, the ascending colon turns sharply to the left, medially and inferiorly, to form the hepatic flexure. The ascending colon is devoid of peritoneum on its posterior surface. It is replaced by areolar tissue (fascia of Toldt) resulting from an embryologic process of fusion or coalescence of the mesentery to the posterior parietal peritoneum. 1, 5 In the lateral peritoneal reflection, the white line of Toldt represents this process. This line serves as a guide during mobilization of the ascending, descending, or sigmoid colon.

Transverse Colon
The transverse colon, measuring approximately 45 cm, is the longest segment of the large bowel. Hanging between fixed positions at the hepatic and splenic flexures, it is completely invested in visceral peritoneum. 1, 6 The nephrocolic ligament secures the hepatic flexure and directly overlies the right kidney, the duodenum, and the porta hepatis. The phrenocolic ligament lies inferior and ventral to the spleen and firmly fixes the splenic flexure in the left upper quadrant. 6 The angle of the splenic flexure is higher, deeper, and more acute than that of the hepatic flexure. Between the flexures, the transverse colon is suspended below the greater curvature of the stomach by a mesocolon that provides variable mobility. The transverse colon may be relatively high at the level of the transpyloric plane or, alternatively, its nadir may reach the hypogastrium. The greater omentum is fused to the transverse colon on its anterosuperior aspect. It is a double layer of visceral and parietal peritoneum (total of four layers) that contains variable amounts of stored fat. 6 Dissection in this plane allows entry into the lesser sac, which is critical in mobilization of the transverse colon. Mobilization of both flexures should be pursued with the utmost caution. On the right side, identification and preservation of the duodenum is paramount. Because of the risk for splenic injury and hemorrhage, mobilization of the splenic flexure should be approached with great care by upward dissection along the descending colon along the line of Toldt, and medial-to-lateral dissection along the transverse colon towards the splenic flexure after entering the lesser sac. 1 This approach allows liberation of the splenic flexure with minimal traction.

Descending Colon
This segment of the large intestine can be 22 to 30 cm in length and courses from the splenic flexure into the left iliac fossa, where it is continuous with the sigmoid colon. The caliber of the descending colon is considerably smaller than that of the ascending colon, and it lies more dorsally in a retroperitoneal position along the left side of the posterior abdominal wall than the ascending colon. 1 Like its counterpart on the right side, dissection along the line of Toldt allows for full mobilization of the descending colon.

Surgical Significance
During anterior resection for rectal cancer, ligation of the IMA distal to the left colic artery is oncologically safe, but its division proximal to the left colic artery may be necessary for a tension-free low pelvic coloproctostomy in addition to complete mobilization of the splenic flexure.

Sigmoid Colon
The sigmoid colon forms an S-shaped (as in “sigma”) loop of variable length that extends from the descending colon to the proximal portion of the rectum. It usually has a long mesentery and, therefore, has considerable freedom of movement. The root of its mesentery has an inverted V-shaped attachment, superiorly along the external iliac vessels and inferiorly from the bifurcation of the common iliac vessels to the anterior aspect of the sacrum. The mesosigmoid is frequently attached to the left pelvic sidewall, producing a small recess known as the intersigmoid fossa. 1 This recess is a surgical landmark for the underlying left ureter. In addition to the left ureter, the bifurcation of the left common iliac artery is posterior to the apex of the mesentery.

The rectum is the fixed terminal portion of the large intestine and serves as a reservoir. It is 12 to 15 cm in length, and its proximal portion is marked by the disappearance of appendices epiploicae and convergence of the taeniae coli to form a complete muscular tube. The definition for the proximal and distal extent of the rectum is controversial. Some consider the rectosigmoid junction to be at the level of the sacral promontory, whereas others consider it to be at the convergence of the taeniae coli. Anatomists consider the dentate (pectinate) line the distal extent of the rectum, whereas surgeons typically view this junction of columnar and squamous epithelium as existing within the anal canal. 6 The rectum occupies the concavity of the sacrum in the true pelvis. Its posterior surface is completely extraperitoneal, in that it is adherent to the presacral soft tissues and, thus, is outside the peritoneal cavity. The proximal third of the rectum is anteriorly and laterally invested by peritoneum; the middle third is covered by peritoneum on its anterior aspect only, and the lower third is entirely extraperitoneal. The anterior peritoneal reflection refers to the junction of the parietal peritoneal covering of the rectum and bladder in men, and the rectum and uterus in women (pouch of Douglas). The location of this peritoneal reflection is more variable in women than in men, and may be quite low in the pelvis. The rectum has three lateral curves: the upper and lower curves are convex to the right, and the middle curve is convex to the left. Endoluminally, these folds are known as the valves of Houston. The clinical significance of the valves of Houston is that they must be negotiated during successful proctosigmoidoscopic examination 1, 4 ( Fig. 1-3 ). The rectum is characterized by the absence of taeniae coli, epiploic appendices, haustra, or a well-defined mesentery. 1, 7, 8 The posterior aspect of the rectum is invested with a thick, closely adherent mesorectum. A thin layer of investing fascia (fascia propria) coats the posterior aspect of the mesorectum and represents a distinct layer from the presacral fascia against which it lies. 6 The term mesorectum is anatomically inappropriate; however, it has gained widespread popularity among surgeons to address the perirectal areolar tissue, which contains the lymphatic drainage system and blood supply. 1, 9 - 11 Total mesorectal excision is a well-described surgical technique that utilizes the tissue planes investing the rectum to achieve a relatively bloodless rectal and mesorectal dissection.

Figure 1-3 Frontal section through the pelvis and rectal valves of Houston. These valves must be successfully negotiated during proctoscopy.

Clinical Significance
The rectum is immune to diverticular disease because its strong, complete muscular tube is able to withstand high intraluminal pressures. Also, lack of vasa recta, which result in weak spots in the muscularis propria, maintain the integrity of the wall of the rectum. Injury to the rectum above the peritoneal reflection may lead to peritonitis and abdominal sepsis.

Fascial Attachments of the Rectum
The walls and floor of the pelvis are lined by the parietal endopelvic fascia, which continues to the internal organs as a visceral pelvic fascia. 1 The fascia propria of the mesorectum is present mainly in the lateral and posterior extraperitoneal portion of the rectum. Distally, this fascia forms the lateral ligaments or lateral stalks of the rectum. These lateral stalks do not contain important structures, but the middle rectal artery and pelvic plexus are both closely related, coursing at different angles beneath them. The middle rectal artery provides minor branches to the lateral stalks on one or both sides in up to 25% of individuals. 1, 9, 10, 12 This is an important consideration during proctectomy, because arterial bleeding may be encountered in this location. Excessive medial traction during lateral mobilization of the rectum may also contribute to postoperative erectile or bladder dysfunction, secondary to stretch injury or transection of the inferior hypogastric plexus.

Surgical Significance
Violation of the presacral parietal pelvic fascia during proctectomy may result in severe hemorrhage from the presacral veins that connect with the avalvular basivertebral veins. The proper plane of dissection is the avascular plane anterior to the presacral fascia and posterior to the fascia propria of the rectum (also known as the Holy Plane of Heald).
The sacrum and coccyx are covered with a strong fascia, which is part of the parietal pelvic fascia. This is known as Waldeyer’s fascia, a presacral fascia that covers nerves, the median sacral artery, and presacral veins. 13, 14 The rectosacral fascia is an anteroinferiorly directed fascial reflection from the presacral fascia at the S-4 level to the fascia propria of the rectum just above the anorectal ring. 1, 14 - 16 The space below the rectosacral fascia is the supralevator or retrorectal space.
Injury to the periprostatic nerve plexus is best avoided by commencing the anterior mobilization of the rectum in the midline between the rectum and the seminal vesicles. The incision is carried to the lateral border of the seminal vesicles and then curved downward and posteriorly to avoid damaging the neurovascular bundle.
Anteriorly, the extraperitoneal rectum is separated from the seminal vesicles and the prostate or vagina by a tough fascial layer known as the visceral pelvic fascia of Denonvilliers. 1, 15 The rectosacral fascia and Denonvilliers fascia are both important landmarks during complete rectal mobilization.

Anal Canal
The anal canal is the terminal portion of the intestinal tract; it has a complex anatomy and unique physiology. This accounts for its crucial role in continence and its susceptibility to many disease processes. The length of the anal canal varies depending on its definition. The surgical or functional anal canal extends for approximately 4 cm from the top of the levator ani muscle to the intersphincteric groove (the sulcus between the internal and external sphincters), whereas the anatomic or embryologic anal canal is shorter (2.0 cm), extending from the anal verge to the dentate line. The dentate line is the “saw-toothed” junction of the endoderm (above) and ectoderm (below) and corresponds to a line of anal valves, which represent the remnants of the proctodeum. 1, 17, 18 This is an important anatomic landmark between two distinct origins of venous and lymphatic drainage, nerve supply, and epithelial lining. 1, 19 Proximal to the dentate line, the intestine has sympathetic and parasympathetic innervation, and the arterial supply is from the hypogastric vessels. Distal to the dentate line, the anal canal receives somatic nervous innervation from the pudendal nerve and vascular supply from the inferior hemorrhoidal system. The epithelium of the anal canal consists of a mucosal lining above the dentate line and a cutaneous lining below it. The anal transition (or cloacogenic) zone is a 0.5 to 1.0 cm strip of mucosa where the intestinal lining gradually transitions from a columnar and/or cuboidal epithelium to the nonkeratinized, stratified squamous epithelium of the anal margin. This transition zone is a source of some anal tumors 1, 20, 21 ( Fig. 1-4 ). The anal margin is a 3 to 5 cm circumferential area of thin, pale skin devoid of hair follicles and glands, caudal to the dentate line. Distal to the anal margin, the skin becomes thicker and acquires hair follicles, apocrine glands, and becomes normal skin. The anal canal is surrounded by strong muscles that can be regarded as two tubes, one surrounding the other. The inner tube, which has visceral innervations, is the caudal extension of the inner circular layer of the muscularis propria and forms the internal anal sphincter. It is histologically smooth muscle and is innervated by the autonomic nervous system. The outer tube has somatic innervations and is formed by the coalescence of the external anal sphincter complex and the puborectalis muscle.

Figure 1-4 The epithelial transition zone of the anal canal magnified 100 fold. CE, Columnar epithelium; SE, squamous epithlium; TE, transitional epithelium.

Surgical Significance
Autonomic, rather than somatic, innervation of the anal canal above the dentate line renders internal hemorrhoidal ligation relatively “painless.”
The anal transition zone is rarely involved with chronic ulcerative colitis, allowing a double-stapled anastomosis during a restorative proctocolectomy operation.

External Anal Sphincter
The elliptical cylinder of skeletal muscle that surrounds the anal canal has three distinct divisions: subcutaneous, superficial, and deep. 1, 22 These divisions do not have a surgical significance. The most distal part (subcutaneous) has fibers attaching it to the skin. The next portion (superficial) is attached to the coccyx by a posterior extension of muscle fibers, which combine with connective tissue, forming the anococcygeal ligament. Above this level, the deep portion is devoid of a posterior attachment and is continuous with the puborectalis muscle. 23
Anteriorly, the fibers of the external anal sphincter insert into the perineal body, where some fibers merge and are continuous with the transverse perinei muscles. The inferior rectal nerve and a perineal branch of the fourth sacral nerve supply the external anal sphincter.

Internal Anal Sphincter
The internal anal sphincter is the distal 2.5 to 4 cm long condensation of the circular, smooth muscle layer of the rectum. Its lowest portion is just above the most distal portion of the external anal sphincter and is 1.0 to 1.5 cm below the dentate line. 1, 24 The sulcus between the internal and external anal sphincters is palpable as the intersphincteric groove.

Levator Ani Muscles
The levator ani muscle, also known as the pelvic diaphragm, is a broad muscle group that forms the greater part of the floor of the pelvic cavity. It is composed of three striated muscles on each side: the iliococcygeus, pubococcygeus, and the puborectalis muscles. 1, 19 The levator ani muscle is supplied by sacral roots on its pelvic surface (S-2, S-3, and S-4) and by the perineal branch of the pudendal nerve on its inferior surface. The iliococcygeus arises from the ischial spine and posterior part of the obturator fascia and inserts on the last two segments of the sacrum and the anococcygeal raphe. The pubococcygeus muscle arises from the anterior half of the obturator fascia and the posterior aspect of the pubis. The puborectalis arises from the symphysis pubis and the superior fascia of the urogenital diaphragm and joins its fellow muscle on the other side immediately behind the rectum; there they form a U-shaped loop that slings the rectum to the pubic bones. This strong structure of the pelvic floor supports the pelvic organs and, together with the sphincter complex, regulates defecation and forms the primary muscle of anal continence. 1, 18, 25
In summary, the external anal sphincter, a striated muscle, is continuous with the puborectalis muscle, whereas the internal anal sphincter, which is smooth muscle, is contiguous with the muscularis propria of the rectum ( Fig. 1-5 ).

Figure 1-5 The superficial muscles of the male perineum. A, Perineal view of the superficial muscles of the male pelvis. B, Relationship of the rectal wall to the anal sphincter complex and surrounding structures.

Blood Supply of the Colon and Rectum
The superior and inferior mesenteric arteries nourish the entire large intestine. The limit between the two territories is the junction between the proximal two-thirds and the distal third of the transverse colon, which represents the embryologic division between the midgut and hindgut. 1 A continuous communicating arcade along the mesenteric border of the colon, the marginal artery, forms a collateral circulation between these two mesenteric arteries. The marginal artery gives rise to the vasa recta, which supply the bowel. The colon is more susceptible to ischemia and necrosis than the small bowel because communications between vasa recta are few.
The ileocolic artery is the last named branch of the superior mesenteric artery, arising from its right side and coursing diagonally around the mesentery to the ileocecal junction. It is a constant vessel and has two chief branches: the ascending branch that communicates with the descending branch of the right colic artery, and the descending branch that gives rise to the anterior and posterior cecal arteries, as well as the appendiceal artery.
The right colic artery is variable in presence as well as origin. This artery may arise from the superior mesenteric artery, middle colic artery, or the ileocolic artery. It may be absent in 2% to 20% of patients. 1, 26 - 28 When present, it supplies the ascending colon and the hepatic flexure, and its branches join with neighboring vessels to contribute to the marginal artery.

Surgical Significance
During anterior resection, if the IMA is divided at its origin (i.e., proximal to the left colic artery), preservation of the accessory middle colic artery (if present) and the left branch of the middle colic artery is mandatory, because this is the arterial supply to the proximal portion of the anastomosis. Thus, splenic flexure mobilization must be approached with great caution to avoid injury to these vessels.
The middle colic artery normally arises from the superior mesenteric artery either behind the pancreas or at its lower border. The artery curves toward the hepatic flexure, then divides into a right branch that joins the ascending branch of the right colic artery and a left branch that anastomoses with the ascending branch of the left colic artery (via the marginal artery). Anatomic variations of this artery include absence in up to 20% of cases and the presence of an accessory middle colic artery in 10%. The middle colic artery may be the main supply to the splenic flexure in 33% of cases. 1, 27, 29
The IMA arises from the left anterior surface of the abdominal aorta approximately 3 to 4 cm above the aortic bifurcation and approximately 10 cm above the sacral promontory at the level of L2-L3. 1 Its first branch is the left colic artery, which bifurcates, and the ascending branch courses directly toward the splenic flexure and joins the left branch of the middle colic artery. The descending branch communicates with the sigmoidal vessels.
The IMA gives rise to the sigmoidal branches, crosses the left common iliac artery, and then acquires the name superior hemorrhoidal (or superior rectal) artery. The superior hemorrhoidal artery lies posterior to the right of the sigmoid colon, coming in close contact with the posterior aspect of the bowel at the rectosigmoid junction.
The “Arc of Riolan,” or meandering mesenteric artery, is a tortuous collateral arterial communication between the superior mesenteric artery and IMA. It courses in the mesocolon roughly parallel to the colon between the left branch of the middle colic artery and the main trunk of the IMA or the ascending branch of the left colic artery. It is present in approximately 7% of individuals and is seen more prominently with distal aortic occlusion, or stenosis of the superior mesenteric artery or IMA. 1, 4 The direction of blood flow within this arc is dependent on the location of the stenosis. If the superior mesenteric artery is stenotic, retrograde flow from the IMA ensures viability of the midgut (small bowel and right colon). If the IMA is stenotic, anterograde flow from the superior mesenteric artery ensures viability of the hindgut (left colon and rectum) as well as the lower extremities.
The middle rectal artery usually arises from the internal iliac arteries. In some cases, it arises from the inferior gluteal arteries. The middle rectal artery can be variable in size and may be absent in 40% to 80% of patients. 1, 25, 30 - 32 When present, it enters the rectum anterolaterally, passing alongside and slightly anterior to the lateral rectal stalks.
The inferior rectal artery is a branch of the pudendal artery, which is a more distal branch of the internal iliac (hypogastric) artery. From the obturator canal, it traverses the obturator fascia, ischiorectal fossa, and external anal sphincter to reach the anal canal. This vessel is encountered during the perineal portion of an abdominoperineal resection ( Fig. 1-6 ).

Figure 1-6 A, The arterial supply of the colon and rectum. B, The arterial supply of the perineum.
During aortic operations, the IMA may be safely ligated, if the flow is anterograde. However, if the flow is retrograde, the IMA must be reimplanted to avoid ischemic necrosis of the left colon.

Venous System and Lymphatic Drainages
The venous drainage of the colon and rectum mirrors the arterial blood supply. Venous drainage from the right and proximal transverse colon empties into the superior mesenteric vein, which meets the splenic vein to become the portal vein. The venous drainage of the distal transverse colon, descending colon, sigmoid, and most of the rectum is via the inferior mesenteric vein into the splenic vein. The venous drainage for the anal canal is the middle and inferior rectal veins into the internal iliac vein and, subsequently, the inferior vena cava ( Fig. 1-7 ).

Figure 1-7 Venous and lymphatic drainage of the large bowel. Systemic circulation shown in dark blue and portal circulation shown in light blue .
The lymphatic drainage of the large intestine starts with a network of lymphatic vessels and lymph follicles in the lamina propria, along the muscularis mucosa, but becomes more abundant in the submucosa and muscle wall. 1, 33 These lymphatic channels are connected with and drain into the extramural lymphatics, of which there are four: epicolic, paracolic, intermediate, and principal. The lymph then drains into the cisterna chyli via the para-aortic chain of nodes (see Fig. 1-7 ). Knowledge of the lymphatic drainage is essential in planning operative treatment for malignancies of the large intestine.
Lymph from the upper and middle parts of the rectum ascends along the superior rectal artery and subsequently drains to the inferior mesenteric lymph nodes. The lower part of the rectum drains cephalad via the superior rectal lymphatics to the inferior mesenteric nodes and laterally via the middle rectal lymphatics to the internal iliac nodes. Lymphatics from the anal canal above the dentate line drain superiorly via the superior rectal lymphatics to the inferior mesenteric nodes and laterally along both the middle rectal vessels and the inferior rectal vessels through the ischioanal fossa to the internal iliac nodes. Lymph from the anal canal below the dentate line usually drains to the inguinal nodes. It can also drain to the superior rectal lymph nodes or along the inferior rectal lymphatics through the ischioanal fossa if the primary drainage basin is obstructed. 33, 34

The large intestine is innervated by the sympathetic and parasympathetic nervous systems, the distribution of which follows the course of the arteries. The peristalsis of the colon and rectum is inhibited by sympathetic nerves and stimulated by parasympathetic nerves.
Preganglionic sympathetic nerves originating from T6 to T12 synapse in the celiac, preaortic, and superior mesenteric ganglia. 6 Postganglionic fibers then course along the superior mesenteric artery to reach the right and transverse colon. The parasympathetic supply to right and transverse colon comes from the right (posterior) vagus nerve as well as the celiac plexus. The left colon and rectum receive sympathetic supply from the preganglionic lumbar splanchnic nerves originating from L1 to L3. These fibers synapse in the preaortic plexus located above the aortic bifurcation, and the postganglionic elements follow the branches of the IMA and superior rectal artery to the left colon, sigmoid colon, and upper rectum. The lower rectum, pelvic floor, and anal canal receive postganglionic sympathetic innervation from the pelvic plexus. The pelvic plexus is adherent to the pelvic side walls and is adjacent to the lateral stalks. It receives sympathetic branches from the presacral plexus, which condense at the sacral promontory into the left and right hypogastric nerves. These sympathetic nerves, which descend into the pelvis dorsal to the superior rectal artery, are responsible for delivery of semen to the prostatic urethra. The parasympathetic nerves, or nervi erigentes, arise from S2 to S4. 1 Preganglionic parasympathetic nerves merge with postganglionic sympathetic nerves after the latter emerge from the sacral foramina. These nerve fibers, via the pelvic plexus, surround and innervate the prostate, urethra, seminal vesicles, urinary bladder, and muscles of the pelvic floor. Rectal dissection may disrupt the pelvic plexus and its subdivisions, resulting in bladder and sexual dysfunction. The level of the neurologic injury affects the severity and the type of dysfunction. Injury to the hypogastric nerves near the sacral promontory results in sympathetic dysfunction characterized by retrograde ejaculation and bladder dysfunction. Injury to the mixed parasympathetic and sympathetic periprostatic plexus results in impotence and atonic bladder. 1, 35 - 39

Surgical Significance
During proctectomy in male patients, the most common site of injury to these nerves is at the point where they enter the seminal vesicles. Failure to preserve at least one of the hypogastric nerves during rectal dissection results in ejaculatory dysfunction in men ( Fig. 1-8 ).

Figure 1-8 Nerve supply of the pelvis.

The colonic wall is composed of four layers: mucosa, submucosal, muscularis propria, and serosa ( Fig. 1-9 ). The mucosa is the innermost layer of the bowel wall and lines the lumen. This layer is further divided into the epithelial layer, the lamina propria, and the muscularis mucosa. The colorectal epithelium is composed of columnar cells, goblet cells, and endocrine (amine precursor uptake and decarboxylase) cells. The lamina propria bears lymphoid follicles, capillaries, and connective tissue, whereas the muscularis mucosae is composed of a smooth muscle layer, richly supplied by blood vessels and lymphatic channels. Invasion of neoplasm into this layer marks the transition from a benign to a malignant process. 40, 41

Figure 1-9 Normal colonic wall histology magnified 20 fold. M, Mucosa; ICM, inner circular muscle; OLM, outer longitudinal muscle; SM, submucosa.
The submucosa lies just deep to the mucosa (muscularis mucosa) and contains lymphatic channels, blood vessels, connective tissue, and the autonomic nerves of Meissner’s plexus.
The muscularis propria is subdivided into an inner circular and outer longitudinal layer and contains Auerbach’s and myenteric plexuses.
The serosa, which is absent in the retroperitoneal portions of the colorectum, represents a visceral peritoneal covering, and contains lymphatics and blood vessels.

The primary physiologic functions of the colon are absorption of water and electrolytes, further metabolism of ingested foods by microfloral metabolism, secretion of electrolytes and mucous, recycling of nutrients, storage of semisolid matter, and propulsion of fecal material towards the rectum. The recycling of nutrients depends on the metabolic activity of the colonic flora, on colonic motility, and on mucosal absorption and secretion. Stool elimination involves dehydration of colonic contents and defecation. 13
In healthy individuals, the colon absorbs water, sodium, and chloride, while secreting potassium and bicarbonate. It receives approximately 1500 to 2000 cc of fluid material from the ileum over a 24-hour period. It has been estimated that the colon possesses enough reserve capacity to absorb an additional 5 to 6 L of ileal effluent, a feature that allows the large bowel to compensate for impaired absorption in the small intestine. 42, 43 Several factors that determine colonic absorption include the volume, composition, and rate of flow of luminal fluid.

Water and Electrolyte Absorption
A central function of the large intestine is to control the level of fecal water. Of the 1500 to 2000 cc of ileocecal flow, only 100 to 150 cc of water appears in stool. Water absorption is intimately related to sodium absorption. The active transport of sodium creates an osmotic gradient across the colonic mucosa that initiates the passive cellular transport of water. Like sodium, water may also move backward into the colonic lumen if it contains a hyperosmolar solution. Ultimately, regulation of water absorption is accomplished by any mediator of luminal flow, fluid composition, or net electrolyte transport. 1, 44
Sodium is absorbed by active cellular transport against concentration and electrical gradients. Initially, sodium moves passively across the apical membrane into the mucosal cell because the intracellular sodium concentration is lower than its luminal concentration and because the cell interior is negatively charged with respect to the lumen.
Sodium is then removed from the cell in exchange for potassium. This is accomplished via a sodium/potassium adenosine triphosphatase (ATPase) pump located at the basolateral membrane. 13, 45 - 47
Mineralocorticoids (aldosterone) and glucocorticoids stimulate sodium absorption and potassium secretion by increasing sodium/potassium ATPase activity. SCFAs, which are produced by bacterial fermentation, are the main anions in the colon, and they also promote sodium absorption. 13, 47
Potassium transport in the colon is mainly passive, along an electrochemical gradient generated by the active transport of sodium. Because the distal colon is relatively impermeable to potassium, the luminal concentration may increase by the continued absorption of water. 13, 43, 46
Chloride concentrations are high in ileal effluent, but fall markedly during passage through the large intestine. Chloride and bicarbonate are exchanged by an electroneutral mechanism. Similar to sodium absorption, chloride is actively absorbed against concentration gradients, mainly through the cellular pathway. The reciprocal exchange between chloride and bicarbonate takes place at the luminal border of the mucosal cell. Chloride absorption is increased by a low luminal pH. The presence of chloride in the colonic lumen facilitates the secretion of bicarbonate 45 ( Fig. 1-10 ).

Figure 1-10 Physiology of fluid and electrolyte absorption across the colonic mucosa.
ATPase, Adenosine triphosphatase; Cl, chloride; CO 2 , carbon dioxide; H + , hydrogen; HCO 3 − , bicarbonate; K + , potassium; Na + , sodium.

Other Constituents
Mucus is another product secreted into the colonic lumen. For the entire length of the large bowel, the epithelium contains a significant number of mucus-secreting goblet cells, and it has been shown that nerve fibers are near these goblet cells. Stimulation of the pelvic nerves increases mucus secretion from the colonic mucosa.
Urea is another constituent of the fluid. The metabolism of urea in the colon gives rise to 200 to 300 cc of ammonia each day. Only a small amount of ammonia can be found in human feces, indicating that most of the ammonia must be absorbed across the colonic mucosa. 13, 42, 48

Products of Bacterial Metabolism
The principal products of bacterial fermentation of polysaccharides in the large bowel are SCFAs or volatile fatty acids, which contain one to six carbons and are the predominant colonic anions. The three most abundant are acetate, propionate, and n -butyrate. These account for 95% of the SCFAs in the colon. These fatty acids are readily absorbed by the colonocytes and provide up to 7% of the metabolic requirements of humans. The colonic epithelium derives approximately 75% of its energy requirements from these fatty acids through metabolism to carbon dioxide, ketone bodies, and lipid precursors. SCFAs also possess antitumor and anti-inflammatory properties, assist with regulation of intraluminal pH for homeostasis of the bacterial flora, and stimulation of mucosal renewal. 49, 50 They have also been shown to increase regional intestinal blood flow. In addition to recovering sodium and water, the colonic mucosa absorbs bile acids that escape absorption by the terminal ileum, making the colon part of the enterohepatic circulation.

Colonic Motility
Colonic motility continues to be poorly understood, but it integrates numerous complex functions, including smooth muscle electrical activity, contractile activity, intraluminal pressure, and both extrinsic and intrinsic neural regulation. 1 Flow of chyme into the colon is regulated by the ileocecal junction, which is thought to function as a sphincter. The ileocecal junction contains a zone of higher pressure than that recorded in either the ileal or colonic lumen. Periodic sphincter relaxation allows ileal contractions to propel chyme into the colon. Unique antiperistaltic, ring-type contractions in the right colon allow thorough mixing of the chyme, microbial metabolism, and absorption of water and electrolytes. 44, 51, 52 Retrograde movements propel stool from the transverse colon back to the right colon to allow further absorption and bacterial fermentation. Additional contractile patterns in the colon are intermittent, rhythmic contractions that result in a segmented appearance of the colon and move luminal contents in an aboral direction. 44, 53
Although these phasic clusters of contractions result in distal propulsion of fecal material, most forward movement of luminal contents takes place during a “mass movement.” Mass movements occur as a result of strong, propulsive, and migrating contractile forces of the smooth muscle of the large intestine. These giant migrating contractions usually last for 20 to 40 seconds in the colon and travel no more than a third of the distance of the colon, emptying all luminal content from that segment of bowel. Giant migrating contractions occur infrequently, normally no more than three times a day in healthy humans. 44, 51, 52, 54, 55 Increased electrical activity and mass propulsion are initiated in the transverse colon and seem to occur primarily after waking or after food intake (gastrocolic reflex), propelling the fecal material into the rectum.
Colonic myoelectric activity has been extensively studied by placing manometric catheters within the lumen. 56 Low amplitude contractions dominate colonic activity. They are more common in the right and transverse colon but present throughout the colon and are thought to be the stimulus for segmental nonpropulsive contractions. High amplitude contractions are less common and are associated with mass movements.

Control of Intestinal Motility
The motility of the large intestine is regulated by both intrinsic and extrinsic nervous systems. The autonomic (sympathetic and parasympathetic) nervous system provides extrinsic control as previously discussed. The intrinsic (enteric) nervous system includes ganglia in the subserosa, Auerbach’s myenteric plexus, and Meissner’s submucosal plexus. These plexuses receive input from the extrinsic nervous system as well as mechanoreceptors and chemoreceptors in the gut wall. They also receive input through interneurons from both adjacent ganglia and from ganglia in the corresponding plexus. These data are processed, and the appropriate contractile response is generated in the intestine. 44, 51, 52
Colonic motility is also under hormonal control, the details of which are under investigation. Cholecystokinin is thought to be a major stimulator of colonic motility, whereas secretin, somatostatin, and vasoactive intestinal peptide are major modulators of inhibition. 41

Feces and Intestinal Gas
In addition to absorbing water and electrolytes and transporting fecal matter, the large intestine serves as a storage compartment for feces. Feces consists mainly of undigestible food stuffs, such as cellulose and bacteria. One gram of wet feces contains up to 10 12 bacteria. Anaerobes, most commonly the Bacteroides sp ., are present in concentrations up to 10,000 times greater than aerobes. Escherichia coli is the most common aerobic organism in feces. A healthy person evacuates 200 to 400 cc of feces per day. Colonic bacteria metabolize many substrates, including bilirubin and bile acids, and, as such, are an essential component of the enterohepatic circulation. Table 1-1 lists the most common colonic bacteria.
TABLE 1-1 Bacterial Composition of the Normal Human Colon and Rectum BACTERIUM LOWER GI TRACT Staphylococcus aureus * ++ Enterococcus faecalis * ++ Enterobacteriaceae (Escherichia coli) * ++ Bacteroides sp. * ++ Bifidobacterium bifidum ++ Lactobacillus sp. ++ Clostridium sp. * ++ Spirochetes ++ Staphylococcus epidermidis ++ Proteus sp. + Pseudomonas aeroginosa * + Corynebacteria + Mycobacteria + Mycoplasmas + Streptococcus mitis +/− Streptococcus pyogenes * +/− Clostridium tetani +/−
++, Nearly universal, 100% presence; +, common, 25% presence; +/−, rare, <5% presence.
* Potential pathogen.
Flatus is composed of nitrogen, carbon dioxide, oxygen, hydrogen, methane, and hydrogen sulfide. These gases represent both exogenous (swallowed) and endogenous products (produced by intestinal bacteria). The overwhelming majority of intestinal gas is swallowed oxygen and nitrogen, whereas the remainder is produced by bacterial fermentation of residual carbohydrates and proteins. 57 Sulfur compounds, primarily hydrogen sulfide and hydrogen disulfide, produce the characteristic odor of flatus.

Physiology of Defecation
The process of defecation is controlled by a complex interplay of anatomic and physiologic factors. Factors that contribute to continence include stool characteristics (volume, viscosity, velocity), characteristics of rectum (reservoir volume, distensibility), neurologic factors (autonomic, sensory, motor, rectoanal inhibitory reflex), and muscular factors (internal and external anal sphincter and puborectalis).
Stool consistency is important because marginal continence may allow leakage of liquid stool, whereas solid stool may be controlled without difficulty. In addition to its reservoir function, the rectum can increase its capacity to accommodate large changes in volume. This adaptation is essential because incontinence occurs if rectal pressure increases rapidly and exceeds anal pressure.
Anorectal sensation consists of both intrinsic and extrinsic components. Intrinsic sensory nerves are located within the distal anal canal and are thought to be important in distinguishing liquid from solids, and gas and somatic nerve endings have been identified up to 1.5 cm proximal to the dentate line. Extrinsic receptors within the rectal wall or puborectalis sense rectal distention and initiate defecation. 41, 58, 59
The internal and external anal sphincters as well as the puborectalis muscle maintain an anal pressure that is important in maintaining continence to fecal material. Some authors believe that the internal anal sphincter is responsible for approximately 50% to 80% of the resting anal tone, whereas the external anal sphincter accounts for 25% to 30%, and the remaining 15% is attributed to the expansion of the anal cushions. 60 - 64 The puborectalis muscle is tonically contracted and maintains the anorectal angle, but is under voluntary control and contributes to the anal squeeze pressure.
Defecation begins with rectal distention as stool enters the rectum after a mass movement. This rectal distention leads to the sampling reflex or rectoanal inhibitory reflex. This is characterized by the involuntary relaxation of the internal anal sphincter and simultaneous contraction of the external anal sphincter, allowing rectal contents to reach the upper anal canal. The sensory fibers in the anal canal then distinguish between solid and liquid stool and gas, and send a signal that the rectum is full, and defecation should proceed.
At this point, the individual determines whether passage of flatus or defecation is socially appropriate. If so, the puborectalis muscle is allowed to relax, straightening the anorectal angle, and relaxation of the external anal sphincter decreases anal canal pressure. Defecation or passage of flatus occurs as intrarectal pressure exceeds anal canal pressure, sometimes aided by voluntary contraction of abdominal muscles and Valsalva’s maneuver.
If an individual chooses not to defecate, voluntary contraction of the external anal sphincter and puborectalis muscles decrease the anorectal angle and increase the anal canal pressure, preventing evacuation of rectal contents. Subsequently, the urge to defecate abates as the internal anal sphincter regains its resting tone, moving rectal contents proximally to the mid and upper rectum until the time is appropriate to expel the contents.


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chapter 2 Diagnostic Evaluations

Armen Aboulian, Ravin R. Kumar

The Bottom Line

• The diagnostic evaluation of all patients with colorectal symptoms starts with a detailed history and physical examination, including a digital rectal examination (DRE).
• Bedside investigative measures such as anoscopy and proctosigmoidoscopy are the initial tools used to formulate a differential diagnosis and guide further testing.
• Flexible sigmoidoscopy and colonoscopy provide direct visualization of the gastrointestinal lumen and offer possible means of intervention.
• Advanced imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, capsule endoscopy, and positron emission tomography (PET) should be in the armamentarium of the clinician and utilized selectively to arrive at a final diagnosis and begin treatment.
As with every other disease process, the initial evaluation of a colorectal disorder is via a directed history and physical examination. There is a wide range of symptoms that patients may describe, yet guided questioning and appropriate examination can often lead to a short list of differential diagnoses. The reader should be well versed in general medical history taking, including questions regarding weight loss, fatigue, and change in bowel habits, which often imply a higher level of concern for underlying disease, specifically malignancy. The details of a complete medical history are beyond the scope of this chapter, but there are specific questions that are essential and are reviewed here pertaining to a few common colorectal complaints.

Abdominal Pain
Abdominal pain is a common complaint and can be generalized or localized depending on various causes. Important historical elements that should be queried include time of onset, intensity, variations in severity, and aggravating or alleviating factors, including the effect of a bowel movement. When the pain is intermittent, the frequency and duration should also be considered. If pain is localized to a specific quadrant, it is often associated with an underlying pathologic process in that quadrant, such as an inflammatory response or an underlying mass. Although a mass alone is often not a direct cause of pain, a patient may report abdominal pain due to obstruction, localized perforation, nerve involvement, or from the pressure effects of the weight of the mass.

Rectal Bleeding
Delineation of the type of rectal bleeding can play a significant role in formulating an accurate differential diagnosis. The initial approach is to determine if the source of bleeding is from the anorectum, also termed as “outlet type bleeding,” or from a more proximal source. The issues that should be addressed are: (1) the amount and color of the blood; (2) whether the blood is mixed with stool or only on the external surface; and (3) whether the blood appears on toilet paper or forms into clots or drips into the toilet bowl. Large amounts of bright red bleeding that drips into the toilet immediately after a bowel movement is a typical presentation for internal hemorrhoids. Minor bleeding often only on the toilet paper associated with painful bowel movements is nearly always associated with anal fissures. Such a presentation should, however, be approached with caution because anorectal cancers may lead to similar complaints. An anorectal abscess, when ruptured, can drain pus and blood, which can be mistaken for rectal bleeding. Thrombosed external hemorrhoids typically present with sudden onset of painful swelling at the anal verge and may eventually result in bleeding from the anus if the clot ruptures through the skin. More proximal bleeding is characteristically mixed with stool, giving it a darker appearance. Lower gastrointestinal bleeding is discussed in detail in Chapter 25 ( Table 2-1 ).
TABLE 2-1 Characterization of Bleeding per Rectum   OUTLET TYPE PROXIMAL   Bright red Black/melena/maroon   Separate from stool (may coat stool) Mixed with stool   On toilet paper only On toilet paper and in stool   Bleeding distinct from bowel movement With bowel movement   Associated with perianal pain or bulge   Differential diagnosis Hemorrhoids Upper GI bleed Anal tear (traumatic/fissure) Arteriovenous malformation Anal mass (benign/malignant) Diverticulosis GI tumor
GI , Gastrointestinal.

Anal Pain
In patients who present with anal pain, the character of the pain, associated aggravating factors such as bowel movements or wiping, presence of bleeding, swelling, itching and palpable mass should be elucidated to aid in the diagnosis. Common causes of anal pain are anal fissures, thrombosed external hemorrhoids, infections and/or abscesses, and anal tumors. Although internal hemorrhoids are often painless, they may become painful with prolapse, thrombosis, and strangulation. Pain that occurs during and after a bowel movement and is described as stabbing or tearing in nature is often secondary to an anal fissure. Pain from perianal and perirectal abscesses make up a significant portion of emergency room anorectal complaints, often described as throbbing in nature. Patients describe the pain as gradually increasing and associated with tender perianal or perirectal swelling, at times accompanied by purulent drainage and fever. Anal pain associated with a mass, bleeding, pruritus, and discharge may be related to anal cancer, condyloma, or distal rectal cancer. Deeper pelvic pain, pressure, and discomfort often aggravated by sitting may be attributed to levator syndrome. Proctalgia fugax is a subtype of levator syndrome defined as pain arising from the rectum due to spasm of the levator muscles ( Fig. 2-1 ). Patients with anal pain often have the wrong diagnosis upon referral to a colorectal surgeon, and require an appropriate examination, possibly even under anesthesia, to differentiate the true cause and to initiate appropriate treatment ( Table 2-2 ).

Figure 2-1 Differential diagnosis of perianal pain.
TABLE 2-2 Characterization of Anal Pain DIAGNOSIS PRESENCE OF BLEEDING RELATIONSHIP OF PAIN TO BOWEL MOVEMENT Perianal abscess Usually no bleeding Usually no association Anal fissure Usually with bleeding Increased with bowel movement Thrombosed external hemorrhoid Usually no bleeding No worse with bowel movement Levator syndrome Usually no bleeding Improvement with bowel movement Anal tumor Usually with bleeding Increased pain with bowel movement

Perianal Itching
Perianal itching is a common yet serious complaint and may be associated with skin irritation, redness, masses, drainage, or discharge. Bleeding can be secondary to skin injury due to scratching and is often noted on the toilet paper. Although most anal itching is idiopathic, other common causes are anal incontinence, seepage, and discharge. Excessive cleansing, use of chemicals and soaps, loose stools, and frequent bowel movements aggravate the condition. Open ulcers, masses, and persistent itching and redness, especially in immunocompromised patients, should raise suspicion for an infectious or neoplastic etiology and require biopsy for diagnosis.

Perianal Mass
In a patient who presents with a perianal mass, there is a limited list in the differential diagnosis pertinent to the perianal region that is not seen elsewhere in the body. Perianal abscesses, external hemorrhoids, condyloma, skin tags from old fissures, and anal cancer make up the majority of patients with this complaint. Most can be identified on inspection alone; however, examination under anesthesia and biopsy may be required for further elucidation. Furthermore, rectal prolapse and severe internal, thrombosed, or strangulated hemorrhoids may also present as perianal mass. Careful physical examination can help differentiate mucosal prolapse from full thickness rectal prolapse. Rectal and mucosal prolapse can be associated with anal incontinence, either by preventing the sphincter from closing properly, or by dilating the sphincter repeatedly and actually causing repeated distension and subsequent weakness. The “toilet test,” asking the patient to sit on a toilet and strain while the physician observes the character and extent of prolapse, is often extremely helpful in precise diagnosis. Some physicians find the use of a mechanic’s mirror on a handle an easier way to perform the examination on the toilet.

Constipation may have any of several meanings to patients: infrequent bowel movements, having to strain to have a bowel movement, bowel movements that are dry and hard, a feeling of incomplete emptying of the rectum after a bowel movement, or any combination of these symptoms. It is important, while taking the patient’s history, to inquire which of these issues is troubling the patient to better direct further evaluation and management. When symptoms fail to improve after dietary modifications and supplementary fiber intake, additional investigations are indicated. Causes of constipation may be categorized into: (1) mechanical obstruction; (2) physiologic obstruction; (3) problems with defecation; and (4) anal sphincter malfunction ( Fig. 2-2 ). Colonoscopy or barium enema (BE) to evaluate the colon for mass lesions and strictures is typically done initially before further tests. Colonic transit studies using Sitz markers or scintigraphy and video defecography are useful in the assessment of colonic inertia and the dynamic change that take place during defecation.

Figure 2-2 Investigative studies of chronic constipation. MRI, Magnetic resonance imaging.

Seepage and Incontinence
Patients can present with various degrees of incontinence to gas, liquid, and solid material. Again, patients may use the word “incontinence” to represent a number of situations: having to wipe the anal area again after a bowel movement, fecal staining on the underwear, difficulty controlling flatus (with a small amount of leakage of mucus), difficulty holding very loose stool, or actual loss of control of normal consistency bowel movements. They should be closely questioned about what specific issues are bothering them, to better direct examination, differential diagnosis, and the need for additional studies. A thorough obstetric history should be obtained with regard to parity, episiotomy, sphincter injury, and past surgical history (e.g., fistulotomy and sphincterotomy). Digital rectal examination can help to evaluate poor sphincter tone and sphincter defects. Anoscopy and sigmoidoscopy can often disclose evidence of prolapsing tissue (internal hemorrhoids, rectal mucosa, or even polyps) as well as assess stool character and consistency. Endoanal ultrasound is useful for investigating the anal sphincter for defects of the internal or external sphincters. Additional tests such as anorectal manometry, pudendal nerve latency, defecography, pelvic MRI and endoscopy are useful in the evaluation, and listed in Table 2-3 with their utilities in identifying the underlying pathology.
TABLE 2-3 Investigative Studies of Fecal Incontinence INVESTIGATIVE MODALITY UNDERLYING PATHOLOGY Endoanal ultrasound Internal and external sphincter defects Anorectal manometry Internal and external sphincter pressure at rest and squeeze Length of high pressure zone and anal canal Electromyography Electromyographic mapping of the sphincter Defecography Anorectal angle, occult rectal procidentia Pudendal nerve terminal latency Pudendal nerve conduction delay Pelvic MRI Rectal intussuception/pelvic organ prolapse; evaluation of mass
MRI , Magnetic resonance imaging.

Diarrhea, with or without abdominal pain, is another complaint used by patients to describe a number of different specific symptoms, such as frequent bowel movements, loose bowel movements, and tenesmus. Several agents such as bacterial, viral, and parasitic infections can cause diarrhea. Common bacterial infections include Salmonella, Shigella, E. Coli and Campylobacter Jejuni . Several viruses such as Rotavirus and Norwalk virus can lead to diarrhea. Medical conditions such as thyroid disease, diabetes, adrenal diasease, and Zollinger-Ellison syndrome should be excluded. Important information to be gathered from an appropriate history includes the following: whether the symptoms are constant or intermittent, aggravating and ameliorating factors, particular food intolerances (of which milk and milk products may be factors, with the onset of milk intolerance occurring with aging in many people), other medications, and total fluid intake. A recent history of travel or consumption of water from non-city water supplies is pertinent, as is the presence of similar symptoms in children or family members with whom the patient may recently have been in contact. The timing of the diarrhea during the day can also have importance: does the patient have three loose bowel movements every morning, then none through the rest of the day? Is this a problem throughout the entire day? Is the patient regularly awakened from sleep by the need to have a bowel movement (this situation is uncommon in functional disorders, such as diarrhea-predominant irritable bowel syndrome)? A careful fluid history should be taken, inquiring about all fluids regularly taken during the day; water, coffee or tea, fruit juices, soft drinks, alcoholic beverages, and dairy products may be contributing factors. Pathologic causes can be divided into infectious, inflammatory, and secretory, such as from mucosal inflammation of inflammatory bowel disease (IBD), proctitis, or large mucus-producing polyps, as well as metabolic, such as celiac sprue or lactose intolerance.

External Inspection and Digital Rectal Examination
An often overlooked, but very important initial diagnostic step is visual inspection of the perianal region. A careful inspection of the perianal region before DRE is warranted. Nodules, skin tags, external hemorrhoids, and perianal skin changes such as lichenification and tiny linear ulcerations (consistent with idiopathic pruritis ani as well as skin conditions such as Bowen or Paget diseases), external fistula openings, tumescence and erythema consistent with perianal or ischiorectal abscesses, and anal fissures are all common findings in the inspection of the perianal area and anal margin. Gentle traction on the perianal tissues will efface the anal margin, often providing a clear view of an anal fissure. A DRE after inspection assesses tenderness (both palpation of the perianal skin and anal canal), the strength and contour of the anal sphincter, the status of the prostate, the levator muscles, the coccyx, and any intra-anal or intrarectal lesions within the length and sweep of the examiner’s finger. In some patients with painful lesions, such an examination can be difficult or impossible; however, with a well-lubricated gentle approach, valuable information can be obtained. Local anesthetic ointments may also be used to improve tolerance to a DRE. However, it is not uncommon to proceed to the operating room to perform an appropriate examination under anesthesia to further elucidate the diagnosis.

After a DRE, anoscopy is the most accessible and widely used tool in the evaluation of patients with symptoms of anorectal disease. The anoscope provides visualization of the distal rectum, upper anal mucosa, anoderm, and the venous plexus. Commonly used types are beveled anoscopes, such as the Buie or Hirschman and lighted Welch-Allen anoscope ( Fig. 2-3 ). In patients with deeper buttock cheeks, the longer length of a Hinkel-James anoscope is helpful. Although there are several types of anoscopes available, all are designed to provide visualization of the most distal segment of the rectum and anal canal, which is often overlooked by the sigmoidoscope or colonoscope. General recommendations are to pick one type of anoscope that is available at the respective institution and obtain comfort and expertise in its use.

Figure 2-3 Hirschman anoscopes in various sizes.
Anoscopy is useful for detection of anal and perianal disease, such as masses, fissures, perirectal abscesses, fistula in ano, and internal hemorrhoids, as well as sexually transmitted disease. Patients with pain may not be able to tolerate conventional anoscopy. Topical analgesia, and/or using a pediatric model (smaller diameter) anoscope or sigmoidoscope is often useful for these conditions. The anoscope is gently inserted, the obturator removed, and visualization obtained. Instead of rotating the instrument while in the anal canal, use repeat withdrawal and reinsertion of the scope with a different orientation to obtain visualization of all four quadrants without producing discomfort or anodermal tears by tethering the mucosa with rotation alone. To detect internal hemorrhoidal, mucosal, or rectal prolapse, the patient may be asked to strain upon withdrawal of the anoscope.

Rigid Proctosigmoidoscopy
Rigid proctosigmoidoscopy allows the visualization of the rectum and the distal sigmoid. A standard-size scope (outside diameter 19 mm) is appropriate in most settings, although smaller diameter sizes are available at 11 or 15 mm. Rigid sigmoidoscopy can be used to accurately localize and measure the distance of rectal and rectosigmoid lesions from the anal verge and is an important technique in surgical decision making. 1 Although most rigid sigmoidoscopes are ~25 cm in length, a typical examination is limited to the rectum distal to the rectosigmoid junction (typically at ~15 cm) due to patient discomfort ( Fig. 2-4 ). A flexible sigmoidoscope is better equipped and better tolerated for visualization of the more proximal colon.

Figure 2-4 Lighted Welch-Allyn disposable rigid proctosigmoidoscope and anoscope.
Rigid proctosigmoidoscopy, often preceded by anoscopy, may add useful information in the examination of the anal canal. Indications for proctosigmoidoscopy include (1) symptoms in the colon, rectum, and anus (e.g., bleeding, discharge, protrusions or swellings, pain, diarrhea, constipation, anal itching); (2) evaluation of previous anorectal surgery; (3) to obtain tissue or stool specimen for further studies; (4) to remove foreign bodies in the rectum; and (5) for application of topical therapy, such as formalin in radiation proctitis.
The procedure may be performed with the patient in the prone jackknife or left lateral positions The scope is inserted and advanced with air insufflation and direct visualization. With circumferential inspection of the entire lumen, the scope is withdrawn and careful description of abnormal findings, including location, size and characteristics, are recorded. Biopsies can be done using biopsy forceps, and fluid can be aspirated. In cases where feces obscure detailed visualization, a large cotton tip applicator, irrigation, and suction device may be used to clear the field. Serious complications of rigid proctosigmoidoscopy are extremely rare yet deserve mention. Tears of the mucosa of the rectum and perforations have been reported in large series and should be considered in a patient who becomes ill after a proctosigmoidoscopy. More common adverse effects include pain (33%) and discomfort by rectal preparation (13%). 2

Flexible Sigmoidoscopy
The flexible sigmoidoscope (FS) is a 60-cm-long endoscope that provides visualization of the sigmoid colon and rectum ( Box 2-1 ). The lower cost and easier maintenance of the instrument as well as lack of a need for sedation with capabilities similar to a colonoscope make the sigmoidoscope popular for evaluation of colorectal disease. The shorter length limits its use to the rectum and colon distal to the splenic flexure. The indications for flexible sigmoidoscopy are similar to colonoscopy. A significant indication and an advantage over colonoscopy lies in the setting where a formal bowel preparation is not immediately available or tolerated. Adequate visualization can often be obtained after administration of low-volume enemas and subsequent defecation. An example would be in the intensive care unit setting, where FS can be used in patients who may not require or tolerate a full colonoscopy to answer certain clinical questions, such as diagnosis of Clostridium difficile or ischemic colitis.

Box 2-1
Flexible Sigmoidoscopy


• Evaluation of distal colon/sigmoid


• Usually performed without sedation (office procedure)
• Lower cost than colonoscopy
• Easier/faster cleaning and turnaround
• May be performed at bedside in critically ill patient


• Limited to colon distal to splenic flexure
• Patient often needs a full colonoscopy in setting of positive findings
Patients with intolerance of insertion of the scope secondary to pain or stricture are relative contraindications to FS use. The procedure should also be used with extreme caution in cases where perforation from insufflation is a concern, such as in acute sigmoid diverticulitis, fulminant colitis, and toxic megacolon.
Complications of FS are rare, but include perforation, bleeding, abdominal distention, respiratory complications, vasovagal reactions, subcutaneous and/or mediastinal emphysema, and inability to complete the procedure. The reported perforation rates are ~0.1%, with most investigators reporting less than that after colonoscopy. 3

Today, colonoscopy is considered the gold standard in diagnosis with an increasing role as a therapeutic measure in colorectal disease processes ( Box 2-2 ). The standard size colonoscope is 160 cm in length; however, it is available in variable stiffnesses and several sizes, including a smaller diameter, more flexible pediatric scope, which is also useful in adults with colonic strictures or sharp, fixed angles ( Fig. 2-5 ) .

Box 2-2


• Cancer screening and cancer and polyp surveillance
• Workup of blood per rectum
• Evaluation of colitis (inflammatory, ischemic)
• Endoscopic removal of polyps
• Colonic stent placement
• Endoscopic submucosal dissection


• Wide spectrum of indications
• Diagnostic and potentially therapeutic tool
• Direct visualization with potential tissue biopsy


• Complications of bowel preparation (dehydration, electrolyte imbalance, discomfort, incomplete preparation)
• Risks of sedation
• Bowel injury (hemorrhage, perforation)

Figure 2-5 Standard colonoscope.
Indications for colonoscopy, both for diagnosis and possible therapeutic applications, include all symptoms that may be related to colorectal disease, including acute and chronic disease, benign or malignant processes, and in screening and surveillance for adenoma and carcinoma. There are several forceps, graspers, and retrieval methods that are in the armamentarium of the endoscopist ( Fig. 2-6 ) . Fig. 2-7 shows a pedunculated polyp removed using the endoscopic snare. More recently, colonic stents have widened the range of therapeutic interventions performed by colonoscopy. Stents may be deployed in the setting of a palliative measure for neoplastic obstruction or as a bridge to surgery. 4 Contraindications include patients with high risk for perforation or suspicion of perforation, such as fulminant colitis, acute diverticulitis, bowel perforation, and peritonitis. A limited examination may be performed in cases of ischemic or acute colitis, although these situations are considered relative contraindications.

Figure 2-6 Endoscopic instruments used by the colonoscopist. Top to bottom: basket for retrieving polyps, biopsy forceps, small snare, large snare.

Figure 2-7 A pedunculated polyp being removed using the endoscopic snare.
Although there are several nontechnical complications of colonoscopy, such as dehydration, electrolyte imbalance, and over sedation, the main and most concerning complications that are a result of either direct or indirect bowel injury are perforation and bleeding ( Fig. 2-8 ) . The overall rates of perforation or bleeding range from 0.01% to 5%, with higher risks during therapeutic procedures. 3, 5 Common sites of colonoscopic perforation are at the sigmoid junction due to excessive traction, often when attempting to maneuver the colonoscope more proximal to the sigmoid. Other common sites and causes of perforation are at the cecum secondary to over insufflation, at a diverticulum from intubation, and at any of the bends from a direct injury by the endoscope tip. Furthermore, a thermal injury may occur anywhere along the colon where an external energy source is used. In perforations secondary to thermal injury, there may be a delay in presentation as the coagulated site undergoes complete necrosis and eventual weakening and perforation of the wall. 5 Post-polypectomy hemorrhage is also a potential complication that deserves further discussion, with reported rates of >1% in the literature. In a case-controlled study of 4592 patients who underwent colonoscopy with polypectomy, 41 patients (0.9%) developed delayed post-polypectomy bleeding and presented on average 6 days after the procedure. 6 Injury to other organs such as the mesentery or spleen were also reported after colonoscopy. There were around 50 reported cases of splenic tears in the literature. Splenic tears can often be managed nonoperatively or with arterial embolization or splenectomy depending on the extent of trauma. 7

Figure 2-8 Mechanisms of colonoscopic perforation. A, Side perforation of the sigmoid from looping of the scope. B, Diverticular perforation from air insufflation. C, Perforation of wall by tip of scope. D, Perforation of cecum from air insufflation.

Computed Tomographic Colography
Computed tomographic colography (CTC), also known as “virtual colonoscopy” is a technique that uses data generated from multidetector CT imaging of the fully prepared and gas-distended colon to generate 2-dimensional (2D) and 3D images of the colon. It uses air as a contrast agent, rather than barium. It has potential as an alternative diagnostic technique to conventional colonoscopy. 8 Reading can be done in reformatted 2D or 3D static modes, 3D “fly through,” and/or with a variety of platforms. A major issue facing the entire field is the wide variation in the technique and lack of standardization. Thorough bowel preparation is mandatory for CTC, because residual stool and large amounts of fluid can obscure small lesions. Fecal and fluid tagging is a promising technique to delineate stool from polyps during virtual colonoscopy. The patient ingests small amounts of barium or iodinated oral contrast. The high attenuated tagged stool can be identified from the rest of the colonic mucosa and suspicious areas such as polyps and cancerous lesions. 9
Current indications for CTC include failed or incomplete colonoscopy, patients with other contraindications to conventional colonoscopy (e.g., bleeding disorders), severe comorbid diseases, and patient refusal of colonoscopy. CTC is not currently approved as a primary screening tool for colorectal cancer (CRC) in the general population. 8 CTC requires bowel preparation similar to conventional colonoscopy, and when abnormal lesions are found, colonoscopy is indicated for tissue diagnosis and for possible removal. Patients do experience mild to moderate abdominal discomfort with insufflation of air, and CTC does have the risk of radiation exposure. There is a reported risk of colonic perforation with CTC (0.06%-0.08%). Perforation risk is increased in the elderly and those with concomitant severe diverticulosis, inguinal hernia, and obstructing lesions ( Fig. 2-9 ). 8, 10

Figure 2-9 Computed tomographic colography work station with both two-dimensional (2D) and three-dimensional (3D) images showing colon polyps.
Although studies indicated sensitivity as high as 100% for lesions ≥10 mm, the sensitivity for smaller lesions falls off rapidly: 83% for lesions measuring 6 to 9 mm and 53% for lesions >5 mm. Overall, the reported sensitivity rates were 74% and specificity of 96% in a large study. CTC and colonoscopy revealed similar efficacy in detection of CRC and polyps ≥6 mm, 11 and an overall per-polyp and per-patient positive predictive value for lesions ≥6 mm was 92% in patient screening using CTC. 12 One of the drawbacks of this technique was the possible large number of false-positive lesions. Additional filters were reported to minimize the false-positive rates to acceptable levels. However, the main disadvantage of the procedure is that when a positive finding is detected, patients then have to undergo traditional colonoscopy to obtain tissue biopsy or possible therapeutic maneuvers. Furthermore, in the setting of high suspicion, the significant risk of false-negative results cannot be ignored, often requiring a traditional colonoscopy to confirm CTC findings. At this point, we do not see a significant role of CTC in our daily practice. Future discussions will likely determine the role of CTC as a cancer screening tool for the average risk patient ( Table 2-4 ).
TABLE 2-4 Comparison of Colonscopy with Computed Tomographic Colography   COLONOSCOPY COMPUTED TOMOGRAPHIC COLOGRAPHY   Well-established standard of care Wide variety of technique without standardization   Diagnostic + therapeutic Diagnostic only Indications Screening Accepted modality in diagnosis of most colorectal diseases

Used when contraindications for conventional colonoscopy (e.g, bleeding disorders, severe comorbid diseases)
Patient preference
Extrinsic compression of the colon on colonoscopy
Following incomplete colonoscopy Bowel preparation Required Required Disadvantages Requires sedation Reported cases of injury to surrounding structures (e.g., splenic and mesenteric tears) Potential for perforation or bleeding

High false-positive rate
High false-negative rate
Requires colonoscopy in setting of positive or negative findings in a patient with a high suspicion Sensitivity High sensitivity

100% sensitivity for lesions ≥10 mm
83% sensitivity for lesions 6-9 mm
53% sensitivity for lesions ≤5 mm Perforation risk 0.05%-5% 0.06%-0.08%

Barium Enema
There are two types of BEs. In a single contrast BE, the colon is filled with barium, which outlines the intestine and reveals large abnormalities, such as large polyps. In a double contrast BE (DCBE) or air contrast BE, the colon is first filled with barium and then the barium is drained out, leaving only a thin layer of barium on the wall of the colon. The colon is then filled with air. This provides a detailed view of the inner surface of the colon, making it easier to see narrowed areas (strictures), diverticula, or inflammation. The air contrast BE is superior to single contrast BE in detecting mucosal abnormalities, and was considered the state of the art before the development of colonoscopy. A complete mechanical bowel preparation is necessary for accurate diagnosis by this means.
When properly performed, contrast enema studies are reliable to detect larger masses, strictures, and other filling defects, as well as to demonstrate fistulas and diverticula. BE alone can miss lesions in the distal rectum, where the balloon catheter used to introduce the barium often still remains during the study. Additional flexible sigmoidoscopy or rigid proctosigmoidoscopy should be done to rule out distal lesions. Other reasons for missed lesions are poor bowel preparation, faulty techniques such as inadequate contrast load, and improper interpretations. Although BE used to have a larger role, its use for screening is limited to those who are at high risk for undergoing colonoscopy due to medical illnesses. As with virtual colonoscopy, BE has significant incidence of false positives and negatives, and lacks the option for biopsy or therapeutic procedures such as polypectomy. It may be used to evaluate the right colon when colonoscopy is incomplete due to technical reasons.
The appearance of a sessile polyp depends on the location of the lesion on the colonic wall. Sessile polyps in the dependent location appear as filling defects in the barium pool, whereas sessile polyps on the nondependent wall appear as ring shadows. Pedunculated polyps can be recognized by the presence of a discrete stalk. Villous tumors can be recognized on DCBE images as polypoid lesions that have granular or reticular appearance because of trapping of barium. CRCs may manifest on DCBE as plaque-like, polypoid, semiannular, or carpet lesions. In one study of DCBE and CRC, 53% appeared as annular, 38% as polypoid, and 9% as plaque-like or carpet lesions. 13 In benign strictures, the narrow segment has tapered borders and preserved mucosal folds ( Fig. 2-10 ). In malignant strictures, the narrow segment has more abrupt shelf-like borders and obliterated mucosal folds ( Fig. 2-11 ). DCBE is a valuable technique for diagnosing IBD colonic alterations, even in patients with early mucosal abnormalities. The earliest finding of ulcerative colitis (UC) is characterized by a fine granular appearance of the colonic mucosa, usually involving the rectosigmoid junction. In chronic UC, double-contrast enema may reveal marked colonic shortening with tubular narrowing of the bowel and loss of haustration. The earliest radiographics findings of Crohn disease are represented by aphthous ulcers, which can progress to form stellate or linear ulcers, transmural ulcers, fissures, sinus tracts, fistulas, and abscesses. 13

Figure 2-10 Sigmoid stricture secondary to diverticulitis.

Figure 2-11 Malignant stricture of colon “apple core” lesion.
BE is simple to perform and is generally safe in the hands of experienced radiologists. The procedure can carry some discomfort, anxiety, and very rarely, bowel perforation. Caution should be used in suggesting BE in those patients with acute inflammatory bowel conditions, recent large biopsies, and fulguration of lesions. BE is relatively contraindicated in patients with partial or complete bowel obstruction, acute diverticulitis, and toxic dilation of the colon. This is due to the risk of perforation and subsequent barium peritonitis, which carries a high mortality. When indicated, a water-soluble contrast enema may be considered in partial or complete large bowel obstruction to evaluate the location, extent, and cause of the obstruction. DCBE has largely been replaced by other modalities as a screening test for colorectal polyps due to its lower sensitivity of 45% and a specificity of 90% for all adenomas. In one study, diagnostic accuracy of DCBE was 54% for any size adenomas and 72% for >10 mm adenomas. 14 Others reported sensitivity of DCBE ranging from 95% to 98% for cancers, 80% to 95% for detection of polyps ≥1 cm, and 50% to 85% for detection of lesions ≤1 cm. 15, 16 DCBE demonstrated significantly lower sensitivity and specificity in detecting polyps ≤6 mm compared with CTC. 17

Water-Soluble Contrast Media Studies
Indications for water-soluble contrast studies include acute and subacute clinical scenarios such as colonic obstruction and pseudo-obstruction, sigmoid volvulus, suspected bowel perforation, and evaluation of anastomotic integrity. The use of barium in such circumstances can carry a risk of barium leak into the peritoneal cavity and cause serious chemical peritonitis, with its significant mortality. Water-soluble contrast media is a clear fluid that does not obscure endoscopic evaluation of the upper or lower gastrointestinal tract. Water-soluble contrast media can cause bowel emptying and can cleanse the colon, although these are not its primary uses. The disadvantage of water-soluble contrast media is its inability to provide detailed evaluation of the colonic mucosa because it does not enhance folds as well as barium, and it is generally not recommended for screening for smaller lesions. Water-soluble contrast enema is often used to study low pelvic anastomosis (as in colorectal, coloanal, and ileo anal J pouch anastomosis) to make the diagnosis of anastomotic leak in the early postoperative period and before take down of a nonfunctioning loop ileostomy. 18, 19

Stool Studies
In addition to the previously mentioned physical examination and endoscopic and radiologic methods of diagnostic evaluation, the following are stool studies that may add further information in regard to a disease process.

Fecal Occult Blood Test
Hemoccult tests are used in CRC screening. Minute quantities of blood from lesions and polyps can be detected by the guaiac fecal occult blood test (G-FOBT) and fecal immunochemical test (FIT). The chemical oxidation of hemoglobin develops conjugated blue quinine compounds. Any blue color developed in the control area is interpreted as a positive test. The Hemoccult II (Beckman Coulter) test is now widely used as a screening tool.
Hemoccult II slides are provided to patients as a package of three tests. The patient collects stool specimens at home for 3 days and returns the test packs to the physician’s office. The patients are given dietary restrictions and told to avoid medications such as nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, anticoagulants, antiplatelets, antimetabolites, and chemotherapeutic agents. Iron supplements or bismuth-containing compounds, such as Pepto-Bismol, may turn stool black, but will not cause a false-positive test result. Red meats, excessive alcohol, and certain vegetables such as turnips and horseradish may lead to a positive test result and should be avoided 3 days before the test. High doses of vitamin C may cause false-negative results. 20, 21
There are four potential pitfalls with FOBT: (1) the sensitivity of G-FOBT for detecting early cancer and adenomas <1.0 cm is relatively low and the reported G-FOBT sensitivity for carcinoma is 12.9% to 54.2%, specificity 95.2% to 97.5% 20 ; (2) although it is a screening test, the false-positive rate may be too high, leading to an unacceptably large number of diagnostic procedures; (3) G-FOBT is subject to failure of appropriate testing due to the dietary restrictions and the collection requirement of multiple stool samples; and (4) in the setting of a positive result, a colonoscopy is still required to identify any lesion and for tissue biopsy or possible therapeutic intervention. However, despite all the disadvantages, a Cochrane Review examined the benefits for screening for CRC using G-FOBT or FIT. In an analysis of four randomized prospective studies, there was a 25% relative risk (RR) reduction (RR 0.75; 95% confidence interval, 0.66-0.84) in mortality from CRC for those completing at least one round of screening using the FOBT. Hence, the authors concluded that there was a modest reduction in CRC mortality, a possible reduction in cancer incidence through the detection and removal of colorectal adenomas, and potentially a less invasive surgery due to an earlier detection and treatment of CRCs. 22 However, with the low sensitivity in identifying the previously described cancers, we believe the role of FOBT for screening in the setting of available colonoscopy is minimal.

Fecal Immunochemical Test
FITs were developed due to the lack of specificity of hemoglobin to FOBT. The specificity of the FIT is based on the use of polyclonal antihuman hemoglobin antibodies that react with undegraded globin molecules in the hemoglobin. FIT is specific for the human blood in stool, and it does not require dietary or drug restrictions before stool collection. Although G-FOBT tests are designed to detect bleeding from the upper and lower gastrointestinal tracts, FIT is more biologically selective in detecting colon and rectal sources of bleeding. The reasoning is based on the degradation of the globin by digestive enzymes that occur in the proximal gastrointestinal tract. In contrast, bleeding lesions from the distal small bowel, colon, and rectum are not exposed to these digestive enzymes and, therefore, the globin is not degraded and will test positive on a FIT. FIT has been approved by the US Food and Drug Administration for fecal occult blood testing.
In FIT, a stool sample in a collection card is rehydrated and brought into contact with a test strip. Human hemoglobin from the stool sample forms a conjugate when brought into contact with antihuman hemoglobin in the test strip. The positive reaction is indicated by a visible pink line color change. FIT has been found to have a more reproducible and higher sensitivity for carcinoma of 87.5% in comparison to G-FOBT and a specificity of 96.6% for carcinoma. 23 Overall, evidence in favor of the substitution of G-FOBT by FIT is increasing, with a relatively higher gain in sensitivity for high-risk adenomas than for cancers. 24 However, the lack of wide availability of the test and higher relative cost limit use to individualized patients.

Fecal DNA Testing
Fecal DNA testing is a more recently described method of cancer detection that deserves mention. Chromosomal instability (CSI) causes approximately 85% of CRC, which is due to mutations occurring in both oncogene and tumor suppressor genes. CSI is often referred to as the microsatellite stability (MSI) pathway. Fecal DNA assays evaluate the presence of CSI by using markers to detect defects in the K-ras, APC, or p53 genes. The premise behind fecal DNA testing is that DNA markers are shed continuously by exfoliation of epithelial cells. Patients are given plastic buckets to collect entire bowel movement and then freeze to temperature of 0°C to 4°C. The packet is then mailed to a laboratory, where fecal DNA assays are performed. A study comparing G-FOBT and the fecal DNA test showed that DNA testing detected 51.6% of the invasive cancers, whereas G-FOBT detected only 14.1%. In cases of adenomas, fecal DNA testing was able to detect 15.1% versus 10.7% for the G-FOBT. 23 Fecal DNA testing is expensive and not covered by most insurance carriers. Clinicians have not found a routine utility for fecal DNA testing. Furthermore, positive test results require colonoscopy; therefore, colonoscopy remains the preferred modality in providing both visualization and diagnosis of carcinoma ( Box 2-3 ).

Box 2-3
Methods of Fecal Screening Tests for Colorectal Lesions

Guaiac Fecal Occult Blood Test

• Detects minute quantities of hemoglobin (blood) in stool
• Wide range of sensitivity to detecting cancer
• High false-positive rates due to dietary factors that may lead to unacceptably large number of diagnostic procedures
• Colonoscopy preferred over this test as it offers both a diagnostic and therapeutic measure

Fecal Immunochemical Test

• Uses antihuman antibodies to detect hemoglobin in stool
• More reproducible and higher sensitivity for carcinoma than guaiac fecal occult blood test
• Colonoscopy preferred over this test as it offers both a diagnostic and therapeutic measure

Fecal DNA Testing

• Detects abnormalities at the gene level of shed markers in stool
• Expensive, not for routine use in the general population
• Colonoscopy preferred over this test as it offers both a diagnostic and therapeutic measure

Tests for Enteritis and Sexually Transmitted Diseases
In patients who present with symptoms such as tenesmus, pain, itching, drainage, or pus with little or no diarrhea, one should consider sexually transmitted anorectal infections. A rectal swab can help to detect common pathogens such as chlamydia, Neisseria gonorrhea, and herpes simplex virus. Acute nonbloody diarrhea in those with no abdominal pain, tenderness, fever, and no history of travel to areas where bacterial diarrhea is prevalent can be self limiting. In acute bloody diarrhea, the cultures should include Campylobacter, Escherichia coli O157:H7, salmonella, shigella, yersinia, and Clostridium difficile . Long-term bloody diarrhea workup should include stool culture that seeks Campylobacter, E coli O157:H7, salmonella, and shigella; antigen or cytotoxicity assay for C difficile, and microscopic stool evaluation for parasites, especially Entameba histolytica . Long-term nonbloody diarrhea tests should include C difficile, and parasites. The parasite testing should include microscopy and antigen testing for Giardia lamblia and Cryptosporidium parvum .
C difficile diagnosis requires a high index of suspicion and depends on clinical data, the laboratory stool studies (e.g., enzyme linked immunoabsorbent assay), and cytotoxic tests. Isolation and culturing the organism from the stool is cumbersome. Stool cultures are the most sensitive, but results take a long time and may lead to delay in diagnosis. Glutamate dehydrogenase enzyme immune assay (EIA) is very sensitive (sensitivity 85%-100%, specificity 87%-98%). The stool cytotoxin test has a sensitivity of 70% to 100% and specificity of 90% to 100%. Diarrheal stool is filtered and added to cultured fibroblasts. The positive test result is the demonstration of a cytopathic effect that is neutralized by specific antiserum. The result is reported as positive or negative. This test is expensive. 25

Evaluation of Small Intestine

Plain Abdominal Films
Plain films of the abdomen are inexpensive, easy to obtain, and indicated when patients present with acute abdominal conditions. The standard plain films should consist of supine, upright, and lateral decubitus radiographs of the abdomen. Plain abdominal films aid in obtaining information on gaseous distension of the stomach, small and large bowels. The colon is identified by the anatomic location and the presence of “haustra.” The small bowel can be confirmed by the presence of circular folds called “plicae circulares.” Plain abdominal radiographs are rarely diagnostic when the patient presents with acute abdominal pain, and one should be aware of the appropriate indications and limitations of abdominal films. However, in the appropriate clinical setting, plain films may help elucidate cases of pneumoperitoneum, pneumobilia, hepatic-portovenous gas, small and large bowel obstruction, toxic megacolon, and volvulus and intramural gas. 26 They may also be used to follow the progress of a patient with Ogilvie syndrome or other causes of colonic obstruction.
Plain film findings can be nonspecific, but it can help the physician to plan further investigations based on the initial suspicion. If plain films are not definite for free air and if there is high suspicion in a stable patient, a CT scan, which is more sensitive for free air, should be obtained ( Fig. 2-12 ). The presence of excessive gas in the small bowel along with air fluid levels and absence of air in the colon indicates a small bowel obstruction ( Fig. 2-13 ). The presence of excessive air distributed along the small intestine, colon, and rectum is suggestive of paralytic ileus. However, it is difficult to distinguish from a bowel obstruction without clinical parameters. The picture of several distended small bowel loops and air fluid levels is often a hint of a more distal obstruction. Findings such as complete bowel obstruction, closed loop obstruction, thick or edematous bowel wall, pneumatosis, and portal venous gas are ominous signs of strangulation and ischemia. 27, 28

Figure 2-12 Free intra-abdominal air seen on computed tomographic scan.

Figure 2-13 Plain film showing small bowel obstruction with air fluid levels.
In mechanical large bowel obstruction, one should look for the extent of the bowel distension, the location of the blockage, which may be seen as a “colon cut off” sign, and the absence of air in the distal colon and rectum, which may indicate complete or high grade obstruction ( Fig. 2-14A ). When cecal distension reaches >12 cm, the risk of perforation increases, although increased risk of rupture correlates best with faster rate of distension and the acute setting rather than the actual size of the cecum. 29 - 31 A distended colon with fecal loading ( Fig. 2-14B ) extending to the distal rectum and anus may be due to constipation and not due to colonic obstruction. Diffuse distension of the colon and rectum may also be due to megacolon or colonic pseudo-obstruction (Ogilvie disease). Plain films in the colonic volvulus can show characteristic findings, such as a U -shaped distended loop extending from the left lower quadrant to right upper quadrant as “bent inner tube” sign. Cecal volvulus can be suspected from plain abdominal films and can be confirmed with BE with 88% accuracy. 31 The finding in plain film in cecal volvulus is that of dilated cecum with medially placed ileocolic vessels, creating a “coffee bean” or “kidney shape.”

Figure 2-14 A, Large bowel obstruction with cutoff sign. B, Large bowel obstruction due to massive fecal impaction.

Small Bowel Imaging
Small bowel barium follow-through (SBFT) and small bowel enteroclysis (SBE) are the mainstays in small bowel imaging. Imaging of the small bowel is challenging due the overlapping loops and enormous length of the small bowel. In SBFT, the patient drinks the dilute barium, and several images are taken as spot films as the flow is followed with fluoroscopy. This study is most useful in determining small bowel size and configuration, sites of mechanical obstruction or narrowing, and for assessing the appearance of the esophagus and stomach, as well as the small bowel transit time. In SBE, a small tube is passed into the duodenum, and the barium is rapidly instilled directly into the small bowel for better distension and visualization of mucosal detail. Following this, air is introduced, to give a “double contrast” effect similar to a DCBE. Oral administration of water-soluble contrast can provide information on small bowel obstruction, but should be used with caution in high-grade complete bowel obstruction. It can further provide useful information in differentiating postoperative small bowel obstruction due to a mechanical source from nonmechanical causes. It can be therapeutic as well, as the hypertonic contrast draws fluid into the bowel, which can then promote anterograde movement.
In recent years, CT and MRI enterography (see Chapter 21 , Figs. 21-3 and 21-4 ) have been gradually evolving as a result of improved spiral and multidetector row CT technology. After a high volume nasojejunal administration of contrast or oral intake, CT images are acquired, reconstructed in thin axial slices, and completed by multiplanar views. CT enteroclysis is helpful in diagnosing Crohn disease, with establishing degree of bowel wall thickening and intensity of mucosal involvement, including the depiction of extraintestinal disease and complications. Furthermore, it has become the imaging modality of choice for localization and characterization of small bowel tumors such as fistula or stricture formation. 32 Limitations exist in identifying chronic obscure gastrointestinal bleeding, with a very high rate of negative findings and a reported diagnostic yield as low as 10% to 20%. 33, 34 Additionally, the assessment of motility disorders remains a challenge in CT enterography in contrast to conventional small bowel studies unless there is later stage organic changes evident at the bowel level ( Fig. 2-15 ).

Figure 2-15 Computed tomographic enterography coronal view showing small bowel obstruction.
Although MR enterography deserves a mention because it is a promising modality for imaging in the future, with the excellent soft tissue contrast resolution inherent in MRI and the absence of ionizing radiation, MR enterography is likely to have an increased role in evaluation of small bowel disorders. 35, 36 However, the limited availability of MR scanners and the long acquisition times are obstacles in the routine use of MR enterography.

Capsule Endoscopy
Capsule endoscopy is a simple, safe, noninvasive technique that is well accepted and tolerated by patients. It allows assessment of the small intestinal mucosa for evaluation of bleeding or IBD. The first use of capsule endoscopy was in 2000, and this technique changed the evaluation of small intestine pathology, such as obscure gastrointestinal bleeding, Crohn disease, small bowel tumors, polyposis, etc. 37 As the camera moves down the small bowel due to peristalsis, it transmits images to a data recorder that is connected to a hard drive. 38 It allows visualization of the entire small bowel without need for sedation, radiation, or surgery ( Figs. 2-16 and 2-17 ). Before the introduction of capsule endoscopy, the distal small bowel could only be visualized by retrograde ileocolonoscopy or double balloon enteroscopy, which are limited by the depth of the insertion and poor patient tolerance. However, today, in the setting where a SBFT or SBE do not provide adequate information, capsule endoscopy plays a larger role. The most widely used indication for capsule endoscopy is to identify obscure small bowel bleeding; however, there is an expanding list of indications, including diagnosis of suspected neoplasm or intestinal polyposis and monitoring of regional inflammation in patients with known Crohn disease or celiac disease 39 ( Box 2-4 ). Capsule endoscopy is more sensitive in detecting causes of obscure gastrointestinal bleeding than push endoscopy, 40 and far superior in diagnosing sources of obscure gastrointestinal bleeding (50%) compared with CT enteroclysis. 41 Completion rates of the examination range near 85% ( Figs. 2-18 and 2-19 ). 42 Although capsule endoscopy is considered a safe method of study, there is a significant risk of retention of the capsule. Reported rates range from 0.9% to 1.4% in large studies, with more than half (59%) requiring surgical removal of the capsule. 42, 43 To circumvent this problem, a dissolvable patency capsule has been introduced, which if caught in a stricture, dissolves into smaller pieces that pass through the intestine. 44

Figure 2-16 Capsule endoscopy with recorder.

Figure 2-17 PillCam endoscopy capsules.

Box 2-4
Indications for Capsule Endoscopy

Bleeding From a Suspected Small Intestinal Source

Making initial diagnosis in

• Suspected Crohn disease: unselected patients or selected patients without any sign of disease on the diagnostic tests and upper and lower endoscopy
• Suspected celiac disease
• Suspected irritable bowel syndrome
• Suspected neoplasm or intestinal polyposis syndrome possibly located in the small bowel

Making initial diagnosis or in specifying the extension of supposed or known disease

• Ileitis
• Regional enteritis of the small bowel
• Vascular insufficiency of the bowel
• Gastroenteritis and colitis due to radiation
• Toxic gastroenteritis and colitis
• Diverticulosis and diverticulitis of the small bowel
• Angiodysplasia in digestive mucosa

Follow-up evaluation in

• Patients with known Crohn disease
• Patients with known celiac disease
• Patients with known small bowel neoplasm or intestinal polyposis

Figure 2-18 Capsule endoscopy showing small bowel tumor.

Figure 2-19 Capsule endoscopy of Crohn stricture.
Recently, the PillCam colon capsule was introduced as capsule endoscopy for colon visualization. PillCam colon evaluation requires thorough preparation of the colon to make the colon free of any residue. It is effective and safe; however, the early version of PillCam had lower sensitivity and specificity in detecting colonic lesions compared with conventional colonoscopy. The second-generation capsule system using PillCam Colon 2 has superior imaging than its predecessor, with an adjusting image frame rate. 45 Its limitations are due to poor bowel preparation and its inability to allow biopsies to be taken. The current indications for capsule endoscopy of the colon are limited to patients who have had an incomplete colonoscopy, have a contraindication, or refuse to undergo conventional colonoscopy (see Box 2-4 ). 46

Double Balloon Endoscopy
Double balloon endoscopy (DBE), also known as push-and-pull enteroscopy, is a new method of endoscopy introduced in 2001 that permits visualization and interventional therapy throughout the small bowel. 47 The procedure can be performed orally or per rectum. The standard apparatus includes a thin endoscope (8.5 mm diameter) and a soft overtube, each with a soft latex balloon attached to the tip that allows for sequential inflation and deflation of the balloons and an advancement of the enteroscope through the small bowel in an accordion like fashion. 48 In experienced hands, the ability to evaluate the entire small bowel approaches 100% when attempts are made from both the mouth and the anus. 49
Recent studies reported procedures such as biopsies, hemostasis, balloon dilatation, stent placement and polypectomy, or mucosal resections to be within the capabilities of DBE. 50 - 52 Meta-analysis of 11 studies compared DBE with capsule endoscopy, and estimated that the overall yield for clinically pertinent small bowel findings were similar (60% vs 57%), with similar rates of finding vascular malformations (24% vs 24%), tumors (11% vs 11%), polyps (11% vs 11%), and inflammatory lesions (18% vs 16%). 53
Considering that wireless capsule endoscopy is noninvasive and has the ability to view the entire small bowel, it is recommended as the initial test of identifying obscure small bowel lesions; however, DBE may be performed in patients with positive findings in the proximal small bowel that require biopsy or therapeutic intervention, those with a suspicion for a small bowel lesion despite a negative capsule study, and patients with active bleeding from the small bowel. Furthermore, as previously stated, the rate of retention of capsules is around 1%, and an increasing number of retained capsules can be removed with DBE as experience grows with this technique. Furthermore, DBE may be the preferred method of evaluation in settings where a small bowel stricture is suspected to avoid capsule retention ( Box 2-5 ).

Box 2-5
Small Bowel Imaging Highlights

Small Bowel Contrast Imaging

• Small bowel follow through and small bowel enteroclysis
• Allows evaluation of small bowel size and configuration
• Identifies sites of mechanical obstruction or narrowing
• Measures small bowel transit time
• Small bowel computed tomographic enterography
• Provides information on bowel wall thickness and mucosal involvement in inflammatory disease
• Provides information on extra-intestinal organs
• Identifies small bowel tumors
• Small bowel magnetic resonance enterography
• Improved soft tissue resolution
• Avoids contrast nephropathy and radiation

Capsule Endoscopy

• Transmits images from within the lumen
• Avoids need for sedation, radiation or contrast
• May have capsule retention at strictures or obstruction points

Double Balloon Endoscopy

• Advances endoscope beyond duodenum
• Allows visualization and potential therapeutic intervention
• Requires sedation
• Low success rates in inspection of entire small bowel

Radionuclide Studies
Nuclear medicine imaging techniques are used for the localization of lower gastrointestinal bleeding. Technetium-99m ( 99m Tc)-labeled erythrocytes are commonly used, which allows prolonged or delayed imaging because of a longer half life. 99m Tc pertechnetate imaging may also be diagnostic of ectopic gastric mucosa in a Meckel diverticulum as a potential source of bleeding. 54 These tests are sensitive for active bleeding at a rate as low as 0.1 mL/min, but to be detected, >3 mL of blood needs to pool at one site. 55 Nuclear scintigraphy is more sensitive than angiography for the detection of active bleeding (see Chapter 25 , Fig. 25-5 ).
A negative red blood cell scintigraphic study was shown to be predictive of a good outcome (i.e., self-limited bleeding). 56 When localization accuracy of positive nuclear medicine scans were evaluated by endoscopy, angiography, or surgery, a range of 40% to 100% and a mean value of 80% were reported. When inaccurate localization in these studies were looked at, the range was 6% to 59%, and the mean value was 25%. 54 Some advocate 99m Tc-red blood cell scintigraphy as a screening test to predict the likelihood of positive arteriography. This rationale is based on the higher sensitivity of the red blood cell scan and its higher likelihood to detect intermittent bleeding. Positive and negative predictive values of 75% and 93% were reported for detectable bleeding on angiography, on the basis of the presence or absence of a scintigraphic blush seen within the first 2 minutes of the study. 57

Mesenteric Arteriography
Mesenteric arteriography ( Fig. 2-20 ) is very valuable in the evaluation, localization, and possible treatment of lower gastrointestinal bleeding. The procedure carries the risks related to vascular catheterization, radiation, and contrast administration. Hydration and intravenous mannitol can be used to minimize renal toxicity of the contrast agents. In the setting of a lower gastrointestinal bleed (see Fig. 2-20 ) as a presenting symptom, diverticular bleeding, evidenced by pooling around the diverticulum, is the most likely source. Angiodysplasia is characterized by small clusters of tortuous vessels often in the right colon, and bleeding can be intermittent and less likely show extravasation.

Figure 2-20 A, Angiogram of superior mesenteric artery. B, Angiogram with selective angiogram of right colic artery showing active bleeding. C, Angiogram demonstrating cessation of right colic artery bleed after coil embolization.
An arteriogram is more specific and less sensitive than radionucleotide localization of gastrointestinal bleeding. Clinical studies indicated that active bleeding can be detected by angiography when the rate of bleeding is >1 mL/min. 58 99m Tc-labeled erythrocyte scintigraphy often proceeds angiography, especially in the lower volume blood loss setting. 54
In the past, CT had only limited application in the diagnosis of intestinal ischemia. With improved technology, multidetector-row CT, 3D reformatting, and the use of water as an oral contrast agent, CT allows better visualization of the bowel and mesenteric vessels. CT angiography is now being used to evaluate acute and chronic mesenteric ischemia in place of conventional angiography. The use of multidetector-row CT with 3D reformatting had increased sensitivity (96%) and specificity (94%) in acute mesenteric ischemia. 59
The following sections discuss other commonly used imaging modalities that are utilized in the workup and diagnosis of abdominal complaints, specifically their role in the setting of colorectal disease.

Abdominal ultrasonography is a noninvasive and widely used test to evaluate liver lesions, masses, and fluid collections. Conventional ultrasound displays the images in thin, flat sections of the body. Advancements in ultrasound technology include 3D ultrasound, which formats the sound wave data into 3D images. A Doppler ultrasound study is a special ultrasound technique that evaluates blood velocity as it flows through a blood vessel, including the body’s major arteries and veins in the abdomen, arms, legs, and neck. Color Doppler uses a computer to convert Doppler measurements into an array of colors to visualize the speed and direction of blood flow through a blood vessel.
For detection of liver masses, the rate of ultrasound detection (53%) was inferior compared with CT (68%) and MRI (60%). When all three procedures were combined, the overall sensitivity was 77%. 60 With the advent of real-time scanning, contrast-enhanced ultrasound can evaluate smaller liver lesions that may not be picked up on CT or MRI. Contrast-enhanced ultrasound showed improved detection rates of liver lesions compared with B-mode ultrasound (87% vs 64%). 61 Intraoperative ultrasound (IOUS) is far superior to other modalities for the detection of liver metastasis. IOUS detected 97% compared with preoperative imaging combined with a far superior intraoperative inspection and palpation (78%). 62 At the time of minimally invasive surgery for CRC, the laparoscopic intraoperative ultrasound (LIOUS) probe provides access to evaluate the liver. IOUS proved to be of utmost importance both in selection of patient and the surgical approach for liver resection.

Computed Tomography
CT scans are widely used in diagnosis of acute abdominal conditions, in evaluation of abdominal trauma, in staging of CRC and in identification of postoperative complications and much more. A dilute 2% suspension of barium solution is used as oral and rectal contrast. Intravenous contrast agents are iodinated agents, and may be contraindicated in patients with iodine allergy. Intravenous contrast is considered helpful in evaluation of intra-abdominal abscesses.
On CT imaging, diverticula appear as small outpouching of the colonic wall. CT can detect early changes of diverticulitis and its complications. CT findings of uncomplicated diverticulitis include focal thickening of the colonic wall, pericolonic stranding, fascial thickening close to the pelvic side wall, and visibly engorged mesenteric vessels in the affected segment ( Fig. 2-21 ). CT is particularly useful to diagnose diverticulitis complications such as abscess, fistula, and perforation. An abscess appears as a fluid collection next to the colon or at a distant site that may contain air and/or debris ( Fig. 2-22 ). CT can be used for guidance of percutaneous drainage of an abscess. CT in colovesical fistula can demonstrate air in the bladder, thickened bladder, and inflamed colonic segment adjacent to the bladder. CT has emerged as the initial imaging method for assessing intestinal ischemia. In nontransmural ischemic colitis, bowel wall thickening, thumb printing, and pericolonic stranding with or without ascites can be seen in CT images. CT can also demonstrate “halo sign” or “target sign.” If there is total vascular occlusion, the bowel wall is thin and unenhanced. CT can demonstrate thrombus in the mesenteric vessel. Pneumatosis and venous gas along with bowel wall thickening are ominous signs, suggesting bowel infarction. CT angiography with multiplanar reconstruction can be obtained to demonstrate occlusions.

Figure 2-21 Computed tomographic scan—diverticulitis.

Figure 2-22 Computed tomographic scan—intra-abdominal abscess.
An abdominal and pelvic CT scan is the common method to stage CRC before surgical treatment. Although CT scan, MRI, and endorectal ultrasound are often indicated in rectal cancer staging, routine use of CT scan in colon cancer in still controversial ( Fig. 2-23 ). CT scan is indicated in situations such as advanced local disease, clinical suspicion for metastatic disease, and/or elevated carcinoembryonic antigen (CEA). The aim of the CT scan is to look for metastatic disease in the liver, regional and distant lymph adenopathy, and to assess involvement of the adjacent structures and intraperitoneal disease ( Fig. 2-24 ). Furthermore, CT with contrast is the best study to diagnose (not demonstrate) colovesical fistula. Some authors support preoperative CT scan, which can influence the treatment planning in colon cancer. 63, 64 CT scan is also used in CRC follow up, especially when there are clinical symptoms and/or elevated CEA levels. Metastatic lesions in the liver are hypodense and best seen in the portal phase of the CT scan.

Figure 2-23 Computed tomographic scan—rectal cancer.

Figure 2-24 Computed tomography showing metastatic disease to the liver.

Magnetic Resonance Imaging
MRI can be used for lesion characterization in cases in which the results from CT or ultrasonography are inconclusive or incomplete. Of available modalities, MRI may provide the most accurate detection and characterization of hepatic disease and can be used for sophisticated assessment of benign and malignant tumors. The excellent inherent soft tissue contrast of MRI can be further improved by nonspecific extracellular contrast agents (gadolinium) and by liver-specific contrast agents, some of which are excreted by the biliary system. These contrast agents are now routinely used for liver imaging and improve the sensitivity and specificity of hepatobiliary MRI. 65
In evaluation of rectal disease, MRI can provide accurate information on perirectal extension and regional lymph node involvement in the preoperative local staging of the primary rectal tumor. MRI can accurately predict surgical resection margin and extramural tumor invasion and is useful in preoperative staging and surgical resection ( Fig. 2-25 ). 66 Although we accept endorectal ultrasound (ERUS) as a method to evaluate tumor and node staging for rectal cancer, it is operator dependent, and problems can arise when scanning high or stricturing lesions. ERUS cannot accurately assess circumferential resection margins or identify other prognostic features (e.g., extramural venous invasion). ERUS also has a tendency for overstaging T 2 tumors, whereas MRI is more accurate and can differentiate peritumoral fibrosis from the broad-based or nodular appearance of an advancing tumor margin. 67 Sensitivities for MRI with contrast agents were significantly superior to those for helical CT. 68 Dynamic MRI may be used as an alternative to dynamic cystoproctography for evaluation of rectal prolapse and pelvic floor dysfunction. 69

Figure 2-25 Magnetic resonance imaging of rectal cancer showing extension into surrounding tissue.

Positron Emission Tomography
PET has emerged as a powerful diagnostic tool for the evaluation of cancer patients. This technique uses 18 F-fluorodeoxyglucose (FDG), which competes with normal glucose to be incorporated into the cell by a membrane carrier-facilitated transport mechanism. The role of PET in CRC is in both treatment response and posttreatment follow up in metastatic disease. CT has sensitivity of approximately 85% for detecting liver metastasis and 33% to 94% in detecting extra hepatic sites such as lymph nodes and omentum. The primary use of FDG PET in colon cancer staging relates to the detection of regional lymph nodes and distant metastatic disease for which PET has a higher sensitivity than CT scan. Although some studies showed PET to be superior to CT in the detection of liver metastasis, others showed that it has limited sensitivity for subcentimeter hepatic lesions. Consequently, CT still remains the principal means of detecting hepatic metastasis in CRC. 70 Flanagan et al 71 reported a sensitivity and specificity of FDG PET for tumor recurrence after CRC resection of 100% and 71%, respectively ( Fig. 2-26 ).

Figure 2-26 Positron emission tomographic scan showing partial right lobe resection with new liver metastasis.
PET can play a role in presurgical evaluation in those patients with high suspicion of metastatic disease and thus improve candidate selection. However, the routine use of PET in the primary diagnosis of colon lesions is not clear. There is normal mild to moderate uptake in the cecum and right colon due to the uptake by higher concentration of lymphocytes. Diffusely increased uptake has also been described in inflammatory colitis, diverticulitis, and abdominal or pelvic abscess. 72 Focally increased uptake within the bowel has been described in benign and malignant lesions in the colon. Abnormal activity in the colon would require further evaluation of the colon by colonoscopy.
Concurrent PET-CT imaging with an integrated system may be especially important in the abdomen and pelvis. PET images are difficult to interpret because of both the absence of anatomical landmarks and the presence of nonspecific uptake in the stomach, small bowel, colon, and urinary excretion of FDG. Concurrent PET-CT imaging provides fusion images for differentiating physiologic and pathologic FDG uptake. In addition, PET-CT has been shown to provide more accurate localization of FDG uptake and improvement in guiding and evaluating therapy in CRC. 73

Anorectal Testing
Anorectal physiologic tests are used to better understand anorectal functional disorders such as anal incontinence, constipation, rectal prolapse, and other pelvic floor disorders. However, the complexity and multifactorial pathologic origin of the disease in addition to a general underreporting of symptoms make functional anorectal disorders a challenge. 74, 75 Physiologic tests include anorectal manometry, cinedefecography, MRI, electromyography, and pudendal nerve terminal motor latency. Clinical indications of anal physiologic tests are anal incontinence, constipation, rectal prolapse, rectocele, solitary rectal ulcer syndrome, descending perineum syndrome, anal fissure, traumatic injury, and IBD. 76 These tests are often complementary to each other. Colonic transit studies are used to evaluate colon transit abnormalities.

Anorectal Manometry
The purpose of anorectal manometry (ARM) is to provide an objective value of intrarectal pressures and anorectal sphincter mechanism and competence. ARM is made up of a pressure sensing catheter and a recording system, such as a polygraph or a computer. The catheter is inserted through the anus to a level of 6 to 8 cm above the anal verge, and measurements are recorded at 1 cm intervals along the axis of the anal sphincter as the catheter is slowly pulled out of the rectum and anus. The measurements are observed to evaluate the following parameters: (1) anal sphincter function; (2) recto-anal inhibitory reflex; (3) rectal sensation; (4) changes in anal and rectal pressures during attempted defecation; (5) rectal compliance; and (6) performance of a balloon expulsion test. 77 Anal sphincter function is assessed by the measurement of resting pressure, squeeze pressure, and functional length of the anal canal. Indications for ARM include but are not limited to anal incontinence, constipation (particularly Hirschsprung disease), and baseline evaluations before anorectal or pelvic floor procedures.
The mean anal canal resting pressure in healthy individuals ranges from 50 to 70 mm Hg, which is lower in women and in the elderly. 78 Fifty percent to 85% of the resting tone is attributed to the function of the internal anal sphincter (IAS), and to a lesser degree to the external anal sphincter (EAS) and expansion of anal cushions. In contrast, the squeeze pressure ( Fig. 2-27A ), which represents the maximal voluntary contraction, is mainly a result of the external anal sphincter function, and can be maintained for periods of up to 1 minute. Rapid distension of the rectum induces a transient increase in anal pressure due to EAS and a more prolonged reduction in anal pressure due to relaxation of the IAS (recto-anal inhibitory reflex) ( Fig. 2-27B ). Abnormalities in this reflex are usually a sign of underlying disease such as Hirschsprung’s. The reader must keep in mind that although DRE is considered a mandatory step in anorectal function investigation, sensitivity, specificity, and predictive values are less than optimal, and a more accurate assessment of anal pressures requires manometry. 79

Figure 2-27 A, Manometry tracing showing maximum squeeze pressure—normal. B, Anorectal manometry showing relaxation in response to rectal distention rectoanal inhibitory reflex. C indicates contraction in response to distention and R illustrates relaxation.

Cinedefecography and Pelvic Magnetic Resonance Imaging
Defecography is a contrast-enhanced (barium and air) fluoroscopic imaging of defecation to study anatomy and function of the anorectum and the pelvic floor. It allows the investigator to assess rectal emptying throughout the entire defecation process in anatomic detail, which captures transient and functional disorders of the pelvic floor. Furthermore, it is particularly indicated in patients with chronic idiopathic constipation to exclude causes of obstructed defecation.
High-density barium paste is introduced into the rectum. A thin barium contrast is given orally to opacify the small bowel. A tampon soaked in barium may be used in the vagina. Contrast in the bladder can be used to study the bladder. The patient sits in a defecography chair, and imaging is done at rest, while squeezing, straining, at evacuation, and postevacuation. The following parameters can be assessed in the cinedefecogram: (1) anorectal angle; (2) perineal descent; (3) anal canal length; (4) rectocele; (5) cystocele; (6) eneterocele/sigmoidocele; (7) anismus; (8) rectal prolapse/intussuception; and (9) incontinence ( Fig. 2-28 ).

Figure 2-28 Spot films of cinedefecography showing nonrelaxing puborectalis.
MRI defecography can be used in place of traditional defecography to study outlet type constipation. Dynamic pelvic MRI, with patients in the sitting or supine position, enables an accurate assessment of the morphologic and functional causes of outlet obstruction. 80 MRI provides better details of structural anatomy with good soft tissue contrast to define anatomic planes, and also has superior temporal resolution for the examination of functional abnormalities ( Fig. 2-29 ). 81

Figure 2-29 Magnetic resonance imaging defecography.

Pudendal Nerve Terminal Motor Latency and Electromyography
A transrectal measurement of muscle contraction after electric stimulation of the pudendal nerve, pudendal nerve terminal motor latency (PNTML) testing indicates the integrity of the motor innervation of the pelvic floor musculature. Testing is usually done with a St. Mark’s electrode placed in the examiner’s finger and inserted into the rectum. The ischial spine is palpated, and the pudendal nerve is stimulated. The response is detected at the striated EAS muscle and recorded. Recordings are made on both sides. Normal values of mean pudendal nerve terminal motor latency are 2.0 ± 0.2 ms. 82 , 83 With greater latency periods, the patient is considered to have a pudendal neuropathy.
Electromyography is primarily used in the assessment of sphincter function in anal incontinence. The electromyographic mapping technique is largely being replaced by endoanal ultrasound mapping of the sphincter complex. In patients with constipation, the test is used to evaluate puborectalis relaxation during simulated defecation. A lack of significant relaxation is consistent with the diagnosis of paradoxic puborectalis contraction or anismus ( Table 2-5 ).

TABLE 2-5 Comparison of Physiologic Anorectal Testing

Colonic Transit Studies
Colonic transit can be assessed by sitz (plastic) marker study or scintigraphy. Measurements of colon transit using plastic radiopaque markers are used to diagnose slow transit constipation. 84 Markers are ingested with a meal and abdominal x-rays are obtained for up to 5 days after ingestion. Normal healthy adults pass all markers within 4 to 5 days. 85 The abdominal radiograph is divided into right colon, left colon, and rectosigmoid to assess transit. Although plastic marker transit study is considered a gold standard with colonic dysmotility, studies have shown wide variation in reproducibility. 86
Scintigraphy or radioisotope tests are done by ingesting a meal with a radioisotope and taking multiple images with a gamma camera to assess the transit. Gastric, small bowel, and colonic transit can be evaluated. This test is not widely available, but some advocate this as the standard test for measurement of intestinal transit. Whole gut transit scintigraphy can be simple and aid in the diagnosis of delayed transit constipation. 87 Recent studies also demonstrated the use of a wireless capsule in the assessment of the whole gut transit. 88

Endorectal Ultrasound
Many types of ERUS ultrasound probes have been developed to evaluate the rectal wall and anal sphincter. These probes have a frequency ranging from 5 to 10 MHz. The focal range of the 7.0 MHz transducer is 2 to 5 cm, whereas a 10 MHz transducer has a focal range of 1 to 4 cm. The higher frequency transducer is preferred to evaluate the rectal wall due to the better near image resolution, and the lower frequency transducer is often used to evaluate the perirectal structures and anal sphincter.
There are two modalities to perform ERUS: (1) a hand-held rotating rigid endoprobe with a 360° axial view (B-K Medical Scanner) ( Fig. 2-30 ), and (2) an endoscopic ultrasound using flexible endoscopic equipment ( Fig. 2-31 ). The B-K radial probe has a 24-cm metal shaft with a rotating transducer tip. The end of the probe is covered with a latex balloon or a plastic cap filled with water. It is important to eliminate all air bubbles to minimize artifacts. Endoscopic ultrasound scopes fall into radial and linear categories. The radial endoscope provides circumferential views at right angles to the shaft of the scope. The linear endoscope provides views in the same plane or line as the scope shaft, similar to images obtained in transabdominal ultrasonography.

Figure 2-30 B-K Ultrasound Scanner with probe.

Figure 2-31 Flexbile endoscopic ultrasound.

Endosonography of Normal Anal Canal
The anal canal is 2 to 4 cm long. The internal sphincter extends from the anorectal junction to 1 cm below the dentate line. The outer longitudinal component of the muscularis propria is smooth muscle that extends down and joins the external sphincter (striated muscle). The puborectalis arises from the pubis and forms a sling around the anorectal junction. During ultrasound, the anal canal has four identifiable distinct layers: a moderately reflective subepithelial tissue layer, a hypoechoic internal sphincter, a hyperechoic longitudinal muscle, and an EAS of mixed echogenecity ( Fig. 2-32 ).

Figure 2-32 Endoanal ultrasound showing sphincters. Hypoechoic layer, internal anal sphincter (A) . Hyperechoic layer, external anal sphincter (B) .
ERUS is commonly used in the evaluation of incontinence. In one study, the sensitivity and specificity in locating the sphincter defect was 100%, and accuracy in the topographic detection of the defect was 90%. 89 Sentovich et al 90 also reported a 100% accuracy of detection of sphincter defects; however, in nulliparous women, endoanal ultrasound (EAUS) falsely identified sphincter injury in 5% to 25% of normal anal sphincters.

Endosonography of the Normal Rectum
The normal rectum is 11 to 15 cm long. The lower two-thirds of the rectum is below the peritoneal reflection and is related anteriorly to the bladder base, ureters, seminal vesicles, and prostate in males and lower uterus, cervix, and vagina in females. In ultrasound, the following five layers can be identified: a hyperechoic interface between the water-filled balloon and the mucosa, a hypoechoic muscularis mucosa, a hyperechoic submucosa, a hypoechoic muscularis propria, and a hyperechoic interface between the rectal wall and the perirectal fat tissue or serosa ( Fig. 2-33 ). ERUS is widely used in the preoperative staging of rectal cancer. Accuracy of ERUS for rectal wall invasion is well studied. With respect to ERUS, Kwok et al 91 pooled 2915 patients to find a accuracy rate of 87% (sensitivity, 93%; specificity, 78%) for depth of penetration. Among cases staged using the tumor-nodes-metastasis system, 11% were overstaged and 5% were understaged. As for nodal status, the pooled accuracy rate was found to be 74% (sensitivity, 71%; specificity, 76%).

Figure 2-33 Endorectal ultrasound showing rectal cancer with enlarged lymph nodes—Stage uT3N1. Layers of bowel wall are shown by arrows after the inner white line, representing the balloon-mucosa interface. A , Mucosa and muscularis mucosa, inner black line . B , Submucosa, middle white line . C , Muscularis propia, outer black line . D , Perirectal fat interface, outer white line . E , Perirectal lymph node.

Simple fistula in ano may not require additional diagnostic imaging. However, a complex or high fistula may need additional evaluation beyond a physical examination to identify the tract and the internal opening. Fistulography, EAUS, and MRI have been used to study the fistula tract. Fistulography is often inaccurate or unreliable, but it may help to identify high and complex tracts in select cases. 92 Recent reports supported the use of EAUS (2D and 3D) and MRI to delineate complex fistula in ano 93 (see Chapter 8 , Figs. 8-9 and 8-10 for CT and MRI fistulography). Fistulography is also useful in colocutaneous or enterocutaneous abdominal wall fistula. A soft rubber catheter can be introduced into the cutaneous fistula tract, and contrast is injected. The flow of the contrast can be studied by fluoroscopy. Larger fistula tracts can be easily demonstrated by BE or small bowel contrast studies and CT contrast imaging. In recent years, EAUS has been demonstrated to be valuable in evaluating anal fistula. The injection of peroxide through the external opening of the fistula appears to improve diagnostic accuracy. The 3D ERUS, which enables reconstruction, can provide a significant contribution to the accuracy in complex fistulas. Ratto et al 94 reported a diagnostic accuracy of 84.3% for the primary tracts and 80.9% for the secondary tracts.

Serologic Biomarkers for Inflammatory Bowel Disease
Biomarkers of IBD are measurable substances in body fluids. The application of IBD biomarkers is cheaper, less laborious, less invasive, and more objective compared with the endoscopy/biopsy based approach. Five biomarkers, antisaccharomyces cerevisiae antibodies (ASCA), perinuclear antineutrophil cytoplasmic antibodies (pANCA), antibodies against outer membrane porin (anti-OmpC), Pseudomonas fluorescens bacterial sequence I2 (anti-I2), and bacterial flagella (anti-CBir), are the most widely studied, and new markers are being developed. 95
ASCA and pANCA were the first serologic biomarkers utilized. ASCA is associated more with Crohn disease, whereas pANCA is associated with UC. The other three markers that were introduced later, were anti-OmpC, anti-I2, and anti-CBir. ASCA and pANCA together have a specificity of approximately 90% for both Crohn disease and UC. 96 Biomarkers are not only useful for diagnosis, but also act as potential predictors of disease location, activity, severity, need for surgery, and prognosis. 95, 97 Patients with Crohn disease who are positive in all four biomarkers have an 11-fold increased risk of developing penetrating and/or stricturing disease. Patients with Crohn disease who are positive for three biomarkers (anti-OmpC, anti-CBir, and anti-I2) are more likely to have small bowel surgery than those who have negative results (97.2% vs 23%). 98
Prometheus laboratories developed quantitative tests that detect serum markers consistent with the presence of IBD. The Prometheus test panel consists of four quantitative enzyme-linked immunosorbent assays for ANCA, immunoglobulin-G ASCA, immunoglobulin-A ASCA, and immunoglobulin-A anti-OmpC antibodies. The Prometheus test panel had a sensitivity of 94% and negative predictive value of 95% for IBD. 99 New serologic markers, such as antiglycan antibodies, antisynthetic mannoside antibodies, serum cytokines, and chemokines were reported and studied in recent years. The current serologic markers are useful, but their clinical utility is limited. The newer markers may aid by helping in diagnosis, risk prediction, predicting therapeutic efficacy, and monitoring treatment.


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chapter 3 Preoperative Management

Bard C. Cosman, Todd W. Costantini

The Bottom Line

• Preoperative risk assessment enables the surgeon to counsel the patient more accurately and choose operations more carefully.
• Preoperative testing can look for risk factors, although most risk factors are not modifiable and serve only as warnings of postoperative complications.
• Because so many commonly ordered preoperative tests are not valuable, it is important to limit preoperative testing to what is actually useful.
• Adherence to published guidelines decreases risk in a number of specific scenarios, including management of β-blockers, antithrombotics, insulin, and perioperative antibiotics.
• The surgeon’s recommendation to operate, choice of operation, and conduct of operation are the most important modifiable factors in most cases.
The preoperative workup for a major operation once included an impressive battery of routine studies; the senior author’s student job was “doing preops”—collecting the results of routine chest x-rays (CXRs), coagulation profiles, urinalyses, etc., and writing them on inpatient charts the night before operations. Today’s more streamlined, outpatient workup has fewer tests, and it emphasizes what can change the patient’s outcome. Although there has been greater progress in streamlining the preoperative workup than in devising preoperative ways to prevent postoperative complications, there are evidence-based guidelines for several aspects of preoperative assessment. The surgeon must keep up with these guidelines, which often become de facto medico-legal mandates shortly after they are issued. However, the preoperative workup still functions more to advise the patient and the treating physicians of the risk of complications, than to actually prevent them ( Table 3-1 ). The most important preoperative decisions—whether or not to operate, and what operation to do—remain in the realm of surgical “art” and judgment.

TABLE 3-1 Schema of Preoperative Patient Conditions*
Ideally, preoperative testing should add evidence-based risk stratification to the surgeon’s intuitive and experience-based risk-benefit assessment. For the demonstrably high-risk patient, this may lead to early cancellation—in favor, for example, of no operation for microperforated diverticulitis or a stent for near-obstructing colon cancer—or a lower risk operation, for example, a perineal approach as opposed to abdominal approach for rectal prolapse, or (controversially) a quick open as opposed to lengthy laparoscopic operation. The preoperative management described in this chapter, the bulk of which comes from the past decade of clinical investigation, is an increasingly powerful tool to advise, and occasionally guide, surgical judgment.
This chapter addresses the larger issues of preoperative management with discussions of routine preoperative testing, stopping or continuing medication, and choice of anesthetic. Starting with the premise that healthy patients do not require a routine workup, we describe the appropriate preoperative workup for patients known to have various diseases and conditions. We then discuss prophylaxis against common postoperative problems: infection, deep vein thrombosis/pulmonary embolism (DVT/PE), catabolism, and nausea/vomiting. Finally, we give a nod to the ideal preoperative clinic, with its goals of limiting unnecessary preoperative tests and improving communication between surgeon and anesthesiologist. Operations and the postoperative period are the subjects of all the other, better illustrated chapters in this book. Because the preoperative workup for an emergency condition is brief and usually uncontroversial, this chapter focuses on preoperative assessment in the elective setting. Colorectal operations are considered to be either anorectal (typically minimal risk) or abdominal (intermediate or high risk).

Overall Preoperative Management Issues

Routine Preoperative Testing
The goal of preoperative testing is risk assessment, which informs the patient’s and surgeon’s decision whether to operate, and the surgeon’s recommendation of which operation to undergo. A secondary, and more elusive, goal is to alter management to decrease risk. 1 Choosing which tests to order preoperatively should depend in part on the planned procedure, and the American Society of Anesthesiologists (ASA) class of the patient ( Table 3-2 ). Speaking of tests such as complete blood count (CBC), electrolytes, CXR, electrocardiograms (ECGs), prothrombin time (PT)/partial prothrombin time (PTT), and liver function tests (LFTs), the ASA Practice Advisory stated that, “routine preoperative tests do not make an important contribution to the process of perioperative assessment and management.” 2 The general guidelines are that ASA I and II patients having Surgical Wound Class I and II procedures should have no laboratory testing at all. Anorectal operations are all Surgical Wound Class II and above, and elective abdominal operations are usually Class II ( Table 3-3 ). Preoperative testing in most ambulatory operations should be eliminated. 3
TABLE 3-2 The American Society of Anesthesiologists Physical Status Classification System CATEGORY DESCRIPTION 1 A normal, healthy patient 2 A patient with mild systemic disease 3 A patient with severe systemic disease that limits function, but is not incapacitating 4 A patient with a severe systemic disease that is a constant threat to life 5 A patient who is not expected to survive the operation 6 A patient who is declared brain-dead, undergoing organ harvest for donation E Denotes an emergent operation
TABLE 3-3 Surgical Wound Classification CLASSIFICATION DESCRIPTION Clean (Class I)

No inflammation
Wound closed primarily
Respiratory, GI, biliary, urinary tracts not entered
No break in sterile technique Clean-contaminated (Class II)

Entry into respiratory, GI, biliary, or urinary tracts
Minimal spillage Contaminated (Class III)

Inflammation present in operative field
Spillage from GI tract
Break in aseptic technique
Penetrating traumatic wound <4 hours old Dirty/infected (Class IV)

Gross purulence
Perforated viscus
Penetrating traumatic wound >4 hours old
GI, Gastrointestinal.
For patients with cardiac disease, specific cardiac evaluation should be considered, but hemoglobin and/or hematocrit (Hgb/Hct), electrolytes, and ECGs are all most cardiac patients need. B-type natriuretic peptide (BNP), a ventricle-secreted marker for heart failure, is a powerful prognostic tool and may be useable in operative planning, although how exactly remains unclear: it can at least inform preoperative risk discussions. If the patient is under a cardiologist’s care, consultation is prudent. For patients with chronic renal disease, CBC, electrolytes, and blood urea nitrogen (BUN) and/or creatinine are appropriate tests, because abnormalities in all of these areas are expected and clinically significant. Diabetics, in addition to glucose measurement, should have BUN/creatinine measured to screen for renal disease. For patients with liver disease, LFTs are appropriate, as are CBC, PT and/or international normalized ratio (INR), and electrolytes.
Considering individual tests, Hgb/Hct before a major operation can establish a baseline for postoperative assessments of blood loss, so these are usually appropriate. It is prudent to check Hgb/Hct in the case of a menstruating woman, because an anemic patient might be treated differently from one who is not anemic. Electrolytes or a “metabolic panel” can also establish baselines for postoperative assessments, which are particularly useful when the operation is expected to involve significant electrolyte losses or shifts. The term “complete metabolic panel” should awaken the surgeon’s mistrust, because it indicates a completeness that is neither real nor relevant, and it implies falsely that this much assessment is somehow protective.
Chest x-ray may be useful preoperatively for aged patients with known pulmonary disease or to differentiate acute from chronic disease, as in a patient with chronic bronchitis. There is no role for preoperative pulmonary function tests (PFTs). Preoperative ECG is useful to look for arrhythmias if there are cardiac risk factors (for example, angina, congestive heart failure [CHF], diabetes, hypertension, history of arrhythmia, shortness of breath, previous myocardial infarction [MI], or smoking). It is widely applied for anyone >50 years old, and for men >40 years old, viewing age as a cardiac risk factor. Unless there has been a recent clinical change, the ECG can be up to 6 months old. 2
PT/PTT is an egregiously overused preoperative test and should not be performed unless there is a history of bleeding or easy bruising. If there is, or if the patient is suspected of having chronic liver disease, only a PT/INR should be ordered. aPTT is for monitoring heparin treatment and has no place in preoperative testing.
The indications for pregnancy testing are medico-legal in origin. The ASA states, “the literature is inadequate … whether anesthesia causes harmful effects on early pregnancy. Pregnancy testing may be offered to female patients of childbearing age and for whom the result would alter the patient’s management.” 2 In today’s litigious environment, it is standard to get a urine pregnancy test the morning of operation for any menstruating woman.
In summary, data for preoperative testing are limited, and what exists does not support routine testing. A preoperative clinic armed with protocols and experience can confer enormous savings compared with the “shotgun” approach to preoperative testing commonly used both by surgeons and primary physicians. In the absence of a preoperative clinic, the surgeon must order, oversee, and manage results from preoperative testing, as it is the surgeon who ultimately proposes the risk of an elective operation.

Continuing or Holding Medications
The general rule is to continue medications throughout the day of operation that are necessary on a daily basis and that do not exhibit rebound effects. Thus, β-blockers and statins are continued. Diuretics, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers are continued if prescribed for CHF; otherwise, they are withheld. Diabetic medication is managed to control glucose postoperatively. HIV medications are continued. Herbal supplements, many of which (e.g., gingko, garlic, ginseng) have some effect on coagulation, should be withheld for 1 day before operation. 4

Choice of Anesthetic
Regional anesthesia (spinal, epidural) as a standalone technique for operative anesthesia has not been proven consistently superior to general anesthesia under any circumstance. For example, although it makes sense intuitively that regional anesthesia would have fewer pulmonary complications, this turns out to be generally untrue. 5 Likewise, the cardiac risks of regional anesthesia are difficult to distinguish from those of general anesthesia. 6 Therefore, preoperative decisions should not be based on the illusion of the greater safety of regional anesthesia. Specifically, antithrombotics (e.g., aspirin, clopidogrel, warfarin), should not be discontinued for the specific purpose of gaining the benefits of regional anesthesia—this would be trading an increased risk for an illusory gain. In a database of 29,000 hernia operations (presumably analogous to anorectal operations in magnitude of operation, anesthetic choice, and risk of complications), there was no morbidity and mortality difference between regional and general anesthesia, with the exception that regional anesthesia patients were more likely to die within 1 week postoperatively. 7
The real benefits of regional anesthesia are limited; there may be improved postoperative pain control, and there is certainly lower risk of postoperative nausea and vomiting (PONV). There is a lower rate of unplanned admission in outpatient cases, and there is potentially less postoperative cognitive dysfunction. 8 Regional anesthesia may be better for the patient with obstructive sleep apnea (OSA).
An epidural catheter or spinal anesthetic may be placed preoperatively for pain control to be used in the postoperative setting, when a patient is relying on general anesthetic techniques for operative anesthesia. Currently, there is no clear mandate to place or not to place a regional anesthetic preoperatively in anticipation of using it postoperatively, 9 and it remains a judgment call for both surgeon and anesthesiologist.
The risks and benefits of choosing regional anesthesia must be weighed, and this is especially true for patients on anticoagulation. If you request regional anesthesia for your patient’s operation, you should know that the American Society for Regional Anesthesia guidelines recommend a 7-day waiting period after the last dose of clopidogrel, and 14 days after ticlopidine, before spinal or epidural anesthesia. There is no restriction at all on regional anesthesia on aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), or subcutaneous unfractionated heparin (UFH). Anticoagulant guidelines include starting regional anesthesia 24 hours after the last dose of therapeutic low-molecular weight heparin (LMWH), 12 hours after the last dose of prophylactic LMWH, and 2 to 4 hours after the last dose of intravenous UFH, but only with a normal aPTT. Regional anesthesia may also be started within 24 hours of the first dose of warfarin, or whenever the INR is normal. 10

Preoperative Management of Patients with Known Diseases

Patients With Cardiac Disease
Patients presenting for elective colorectal surgery often present with cardiac risks, MI, arrhythmias, and sudden death. It seems rational to risk stratify such patients, and then intervene preoperatively to decrease cardiac risks. The former is straightforward, but the latter is surprisingly unhelpful, at least in the highest and lowest risk categories. Nevertheless, American Heart Association/American College of Cardiology (AHA/ACC) guidelines for cardiac risk assessment for noncardiac operations can help with operative planning. Like most guidelines, they provide valuable risk reduction for the surgeon, and often for the patient.
Anorectal operations are all in the AHA low-risk category, with MI risk <1%. For this risk category, a study of 19,500 elderly cataract patients, most of whom had some significant cardiac disease risk factors, is pertinent: randomized to having either CBC/electrolytes/ECG or no testing at all, both groups had the same minimal risk of MI (0.3 vs 0.5 per 1000 operations) and death (0.2 vs 0.1 per 1000 operations) within 1 week. 11 (Cataract surgery is typically performed under local anesthesia, whereas anorectal operations may be done under general anesthesia in the prone position requiring endotracheal intubation.) Thus, there is no cardiac workup at all before anorectal operations, except what the anesthesia team demands as a matter of routine—commonly an ECG in men >40 years old and in women >50 years old. A nihilistic approach to preoperative testing makes sense for minor operations.
Elective abdominal colorectal operations are usually in the intermediate-risk MI category, based on the type of operation alone, of 1% to 5%. MI risk elements in the cardiac history are unstable angina, acute decompensated heart failure, significant arrhythmias (high-degree atrioventricular block, symptomatic bradycardia, and ventricular tachycardia), and severe valvular disease (aortic stenosis and symptomatic mitral stenosis) ( Table 3-4 ).
TABLE 3-4 Cardiac Disorders for Which Patients Should Undergo Evaluation and Treatment Before Noncardiac Surgery CARDIAC CONDITION EXAMPLES Unstable coronary syndromes Unstable or severe angina, recent MI Decompensated heart failure NYHA Class IV, worsening, or new-onset heart failure Significant arrhythmia High grade AV block Symptomatic ventricular arrhythmias Supraventricular arrhythmia with uncontrolled heart rate Symptomatic bradycardia New-onset ventricular tachycardia Severe valvular disease Severe aortic stenosis (valve area <1 cm 2 or symptomatic)
AV , Atrioventricular; MI , myocardial infarction; NYHA , New York Heart Association.
Adapted from American Heart Association/American College of Cardiology guidelines.
Preoperative stress imaging, including vasodilator stress nuclear perfusion testing or dobutamine stress electrocardiography, was studied in a collective review of >2000 patients: positive predictive value of stress imaging was not >20%, whereas negative predictive value was nearly 100%. 12 These tests, if negative, provide some reassurance, but they do not indicate MI risk well when they show reversible changes, so it is unclear what to do with a positive result.
Thus, for abdominal operations, the historical “stress test” of moderate exercise tolerance is sufficient, and no further cardiac testing is warranted other than an ECG. If a patient has poor exercise tolerance or has a significant risk factor (age >70 years, angina, previous MI, heart failure, treated diabetes, or creatinine >2 mg/dL), then guidelines recommend stress imaging, if the result will change management. 13
If stress testing suggests a coronary lesion that may amenable to stenting or coronary artery bypass grafting, should those be done preoperatively? Even before vascular operations—a higher risk group of patients than those having colorectal operations—the answer from the Coronary Artery Revascularization Prophylaxis (CARP) trial was that these procedures were not needed. 14 Although taking time to revascularize the heart delayed the needed noncardiac operation significantly, it did not have any morbidity benefits.
To date the best marker for risk of cardiovascular events after noncardiac operation is BNP. Elevated BNP is also a marker for all-cause mortality. 15 Now that there is, for the first time, a single powerful prognostic test, the question of what to do with the information remains. This test should be considered whenever the patient is subjectively at significant risk for operative mortality, to inject caution or confidence, whichever is appropriate, to the preoperative discussion of risks and indications.
For the high-risk cardiac patient, cardioprotective medication seems a reasonable choice. Studies from the 1990s suggested broad application of perioperative β-blockade. However, the Perioperative Ischemic Evaluation Study (POISE) looked at high-dose metoprolol, started immediately preoperatively and continued postoperatively, in >8000 patients. Although nonfatal MI decreased as predicted, stroke and overall mortality increased, to everyone’s surprise. 16 In yet-to-be-revised guidelines released before the POISE trial results, the AHA/ACC recommended preoperative β-blockade for intermediate- and high-risk patients having abdominal operations. 17 This recommendation, now obsolete, has been replaced by the modest mandate that patients already on β-blockers should not miss a preoperative dose. Currently, there is no recommendation for giving preoperative β-blockers to patients who have not been previously prescribed these medications.
The search for cardioprotective medication continues, and preoperative statins seem to lower cardiac risk. 18 Today’s conclusion is that if a patient is already on a statin or a β-blocker, it should be continued through the day of operation. In the future, we may be adding statins to patients’ medication lists preoperatively, but currently doing so would be premature.
Thus, clinical risk factors are sufficient to identify patients’ risk for cardiac complications. Noninvasive imaging may be applied to high-risk and poor exercise tolerance patients, but the results are advisory only. Prophylactic revascularization does not help unless the patient has acute ischemia—the same as in non-preoperative patients. The practical advice for the surgeon is to get a history, consult the primary physician or cardiologist in a high-risk situation, but otherwise to take a minimalistic approach to preoperative testing for major operations as well as minor ones. This may be surprising advice after decades of aggressive stress testing, risk stratification, and coronary revascularization, but it has been justified by recent studies. 17

Special Considerations in Patients With Cardiac Disease

Patients With Coronary Stents
If a patient has a stent in place, AHA/ACC recommends delaying elective operations 30 to 45 days after placement of a bare-metal stent and 1 year for a drug-eluting stent. 17 The problem requiring clinical judgment is picking who cannot wait, and then operating within these periods on antithrombotic medication (see Patients on Antithrombotic Medications, later).

Patients With Automatic Implanted Cardioverter Defibrillator or Pacemaker
Like coronary stents, automatic implanted cardioverter defibrillators (AICDs) are increasingly common: >500,000 Americans have one, and >115,000 new devices are implanted per year, mostly in the same age groups that need colorectal operations. 19 The ASA Practice Advisory is vague, but includes discussing the likelihood of electromagnetic interference with the anesthesiologist. 20 Because monopolar cautery current travels from the site of application to the grounding pad (usually on the thigh), the pacemaker or aids can usually be left alone in anorectal operations because there is little chance of interference. If the patient is pacemaker-dependent and interference is likely, as is common in abdominal operations, then switch the pacemaker to asynchronous mode and turn off its adaptive features. AICDs should either be turned off in a monitored setting, or reprogrammed to monitor only mode. Both of these functions can usually be done with an external magnet. Both anesthesiologist and surgeon must ensure that either device is turned on again postoperatively. This may require simply removing the magnet, or it may require postoperative interrogation to assure correct settings.

Patients With Pulmonary Hypertension
In patients with pulmonary hypertension, general anesthesia has a 7% 30-day mortality and >40% morbidity, both of which correlate with duration of operation. 21 The common complications are respiratory failure, cardiac dysrhythmias, and CHF. The surgeon can help by taking a history and identifying patients with pulmonary hypertension, restricting their interventions as much as possible, keeping operations rapid (this is an argument against laparoscopy), and communicating preoperatively with the primary physician and anesthesiologist. Even minor operations on these highest risk patients should be done in a closely monitored setting, usually a hospital. This population of high-risk patients may be ideally suited to receive regional anesthesia, as the risks of intubation for an elective operation may be significant.

Patients With Pulmonary Disease
Postoperative pulmonary complications (PPCs), which are usually defined as pneumonia, respiratory failure requiring ventilation, atelectasis requiring bronchoscopy, pleural effusion requiring intervention, and significant bronchospasm, cause approximately 20 million additional hospital days and 50,000 deaths per year. In a study of about 1000 patients with major operations, the rate of PPCs was 2.7% within 7 days of operation, and mean hospital stay increased from an average of 4 to 27 days. Both patient factors and procedure-related factors were at work. Risk factors for PPCs were age, smoking, ratio of forced expiratory volume in 1 second to forced vital capacity, duration of anesthesia, upper abdominal incision, and nasogastric tube. Surprisingly, obesity was not a risk factor for the development of pulmonary complications, nor was diabetes. 22
It is not clear that it helps to tell patients to stop smoking shortly before operation, and a well-conducted small trial in patients who underwent elective major colorectal operations showed no postoperative benefits to a smoking cessation intervention performed 2 to 3 weeks before the operation. 23 It is still reasonable to ask patients to stop smoking at any time before operation, because various preoperative interventions, including nicotine replacement therapy, modestly decrease postoperative complications. 24, 25 Other than counseling patients to stop smoking, the surgeon cannot do much about the patient factors that predispose to PPCs. Where the surgeon can help is in keeping incisions low on the abdomen (this is an argument for laparoscopy, and for transverse incisions), operating fast (this is an argument against laparoscopy), and not using a nasogastric tube.
Most PPCs occur in patients with chronic obstructive pulmonary disease. Patients with asthma are also at risk for PPCs, but these tend to be minor and manageable. Risk factors for exacerbation of bronchospasm are recent active disease, evidenced by recent asthma symptoms and treatment, and history of intubation. 26
Several authors compiled risk indexes for the most serious PPCs. Significant risk factors for pneumonia from a Veterans Affairs study included type of surgery (colectomy was one of the safer ones), age, BUN, weight loss, chronic obstructive pulmonary disease, emergency, steroids, and current smoking. 27 Significant risk factors for respiratory failure from a large multi-institutional study included a wide variety of elements, seemingly drawn from every measure of health. 28 One constant in all respiratory failure studies was that low serum albumin was a significant risk factor, emphasizing the role of preoperative nutrition status in preventing PPCs.
Despite the importance of PPCs, preoperative testing for pulmonary disease is of little or no value. On PFTs, the American College of Physicians states: “spirometry may identify patients at risk for PPCs, but while PFTs diagnose obstructive lung disease, this does not translate into effective risk prediction for individual patients. Its value before non-thoracic surgery remains unproven.” 29 The preoperative CXR is similarly of minimal value in the patient who is not acutely ill; evidence favoring its use is limited to upper abdominal, thoracic, and open aortic operations, rather than colectomy. If a CXR is requested as part of a preoperative workup, it should be in elderly patients with history of pulmonary disease and no CXR in the past year. Preoperative arterial blood gas has been replaced by oxygen saturation, which can be measured in the preoperative clinic.
In summary, although PPCs contribute much to postoperative morbidity and mortality, there is almost no role for preoperative pulmonary testing. Unchangeable features make patients high or low risk; therefore, the decision whether to operate, and what operation to do, is paramount. The surgeon’s overall impression of the patient, reinforced or modified by a primary care or pulmonary consultation, remains the best defense against PPCs.

Patients With Liver Disease
Like the patient with pulmonary disease, the patient with liver disease usually has a fixed-risk status that can be assessed but not changed. The Child-Turcotte-Pugh (CTP) classification of cirrhosis, originally designed to risk stratify patients for portal-systemic shunting, is a good risk stratifier for abdominal operations overall, with CTP A, B, and C patients having approximately 10%, 30%, and 80% surgical mortality, respectively ( Table 3-5 ). 30 CTP classification is based on three objective measures—albumin, INR, and bilirubin—and two subjective measures—ascites and encephalopathy. The Model for End-Stage Liver Disease (MELD) score, which uses only the three objective elements of creatinine, INR, and bilirubin, is a more reproducible risk stratifier for elective operation. 31

TABLE 3-5 Child-Turcotte-Pugh and MELD Classification for Liver Disease
A patient suspected of having liver disease should have LFTs (looking for acute hepatitis), bilirubin, albumin, PT, and CBC. A prognostic and therapeutic maneuver is to give vitamin K before operation; coagulopathy not responsive to parenteral vitamin K is a poor prognostic factor. 32 When a patient with severe liver disease cannot avoid an abdominal operation, this is one of the rare situations in which preoperative hospital admission is justified. Diuretics, low sodium diet, and paracentesis for ascites, lactulose for encephalopathy, getting INR to <1.5 and platelets to >50,000, nutritional supplementation, and optimizing renal function are all useful, short-term measures that can be taken preoperatively to reduce operative morbidity and mortality. The standardized cutaneous bleeding time test, in this, as in other situations, has been declared obsolete by laboratory pathologists, and is not available at most hospitals. 33

Diabetic Patients
Diabetes is such a risk for MI that simply having type 2 diabetes for over a 7-year-period carries the same future MI risk as having had a previous MI. 34 Diabetics are prone to clinically silent cardiac ischemia, and diabetes is a significant feature of all cardiac risk indexes. 35 Diabetes is an even more significant risk factor for cardiovascular disease in women than in men. 36 This fixed or chronic aspect of diabetes should contribute to the surgeon’s assessment of whether to operate, and what operation to do. The short-term or acute management of diabetes also makes a difference.
The mere fact of having an operation makes hyperglycemia worse, by a hormonal mechanism, 37 and hyperglycemia is a significant risk factor for postoperative complications across the board. Current recommendations for the diabetic patient preoperatively are to take long-acting insulin the previous evening, as usual, and if there is an insulin pump, keep it at its basal infusion rate. Take one-half of the usual dose of intermediate (e.g., isophane insulin suspension) insulin the morning of operation. For immediate preoperative glucose control, use regular or rapid insulin every 4 to 6 hours. 38 Hold oral antihyperglycemics, including metformin, for at least 8 hours before operation, which usually means holding the morning dose on the day of operation. The Surgical Care Improvement Project (SCIP) currently includes an initiative for postoperative glucose control (glucose <200 mg/dL at 6 AM postoperatively) in cardiac surgery patients. This initiative does not currently include colorectal surgery patients, but may in the near future. Thus, ensuring preoperative glucose control may become increasingly important as postoperative hyperglycemia becomes an outcome measure.
In managing the individual diabetic preoperatively, the advice of an internist or endocrinologist who knows the patient, having been with him or her through previous crises and operations, is invaluable, although it has not been demonstrated in the literature.

Patients With Hypertension
A major meta-analysis of hypertension and perioperative risk 39 concluded that although hypertension is a long-term risk to patients’ health, in the short-term it confers only a slight increase in perioperative events, and those are not clinically significant ones. Preoperative hypertension is a risk factor for postoperative hypertension, but not stroke or MI. Patients with newly diagnosed and previously untreated hypertension, or those patients with uncontrolled hypertension despite medications, should have their blood pressure reasonably well controlled before proceeding with an elective operation.
Practically, the only recommendation to draw from the literature about preoperative hypertension is to continue a β-blocker that the patient is already taking through the day of operation. No operation should be cancelled on the grounds of elevated preoperative blood pressure.

Patients With Sleep Apnea
OSA afflicts >10% of Americans >65 years old, and even in a young (mean age 44 years) and gender-balanced general surgery patient population, 10% had either convincing OSA symptoms or a positive sleep study. 40 Compared with the general population, OSA patients have a fourfold postdischarge mortality after major operations, 41 associated with increased respiratory and cardiovascular morbidity. 42 Simple preoperative questionnaires such as Chung’s s noring, t iredness during daytime, o bserved apnea, and high blood p ressure (STOP) screening tool ( Box 3-1 ) should be part of all preoperative evaluations, both when deciding whether to operate and what operation to do, and also in the immediate preoperative briefing. 43 ASA guidelines for the identified or suspected OSA patient suggest using regional anesthesia and have a lower threshold for hospital admission to a monitored setting. 44 In hospitals that use these guidelines as a mandate for overnight monitoring of the OSA patient who has had a general anesthetic, the presence of OSA may determine anesthetic choice, especially in anorectal operations.

Box 3-1
STOP Questionnaire Used to Screen Patients for Obstructive Sleep Apnea *
Question 1: Do you snore loudly (louder than talking or loud enough to be heard through closed doors)?
Question 2: Do you often feel tired, fatigued, or sleepy during daytime?
Question 3: Has anyone observed you stop breathing during your sleep?
Question 4: Do you or have you been treated for high blood pressure?
STOP, Snoring, tiredness, observed apnea, high blood pressure.

* Patients answering yes to two or more of these questions are at high risk for having obstructive sleep apnea.
Most patients with OSA do not know they have it, and we do patients a great service by identifying OSA in the preoperative period, either by suspicion or by a formal sleep study. It is probably worth delaying elective colorectal operations, especially minor ones, to do sleep studies and allow diagnosed patients to become comfortable with their positive airway pressure devices. It is also advisable to have patients with diagnosed OSA bring their personal continuous positive airway pressure machines for use while in the hospital postoperatively.

Morbidly Obese Patients
Obesity predisposes to OSA, diabetes, hypertension, and impaired exercise tolerance, and on a practical level increases the risk of surgical site infections (SSIs) and hernias. However, obesity itself is not a risk factor for postoperative pulmonary complications, nor does it increase unplanned admission after ambulatory operations. 45 The morbidly obese patient should probably either be sleep-studied preoperatively for OSA or treated perioperatively as if he or she has OSA. The morbidly obese patient without known diabetes should also be treated as a possible diabetic, with close glucose monitoring.

Patients on Antithrombotic Medications
Increasing numbers of patients are on anticoagulant and antiplatelet agents. The goal of preoperative management is to balance clotting against bleeding risks. Anticoagulants are used for prosthetic cardiac valves, chronic atrial fibrillation, and DVT/PE, and antiplatelet agents are used to reduce cardiovascular risk and to keep coronary stents open. Understanding the indication for your patients anticoagulant or antiplatelet therapy is key in guiding perioperative management of these medications ( Table 3-6 ).
TABLE 3-6 Preoperative Management of Commonly Used Antithrombotic Agents ANTITHROMBOTIC AGENT MECHANISM OF ACTION RECOVERY OF CLOTTING FUNCTION Aspirin Irreversible platelet inhibition 7-10 days Clopidogrel Irreversible platelet inhibition 7-8 days Warfarin (Coumadin) Inhibits vitamin K-dependent clotting factors 5 days

The patient on warfarin (Coumadin) is obviously at risk for surgical bleeding, but for small-wound anorectal operations such as simple fistulotomy or internal sphincterotomy, the safest thing may be to continue warfarin and do the operation under local or general anesthesia. For larger or less controlled anorectal operations such as stapled hemorrhoidopexy or hemorrhoidectomy, and for all abdominal operations, reducing the INR to <1.5 is safe and prudent. Meticulous surgical technique to ensure control of all possible bleeding sites is especially important for the patient on anticoagulation.
To correct a patient’s coagulopathy preoperatively, warfarin should be withdrawn 5 days before operation, with or without a heparin “bridge.” The use of a bridge is subject to the judgment of the surgeon, cardiologist, and/or primary care physician, and should not be informed by randomized, controlled trials. Patients should probably be bridged if they are at moderate to high thrombotic risk (prosthetic valve or DVT/PE history), and not bridged if they are at low risk (atrial fibrillation). One can bridge with therapeutic LMWH or UFH; LMWH should be discontinued 24 hours before operation, and UFH 4 to 6 hours previously. 46 LMWH bridging can be done in the outpatient setting, whereas UFH requires an admission not usually covered by insurance, so most bridging is done with LMWH.

Antiplatelet Agents
Aspirin, ticlopidine, and clopidogrel all partially inhibit platelet function. There is no practical way to monitor response to antiplatelet therapy. Because bleeding time and platelet function studies do not correlate with perioperative bleeding, they are not useful to do. Both antiplatelet medication withdrawal and operation induce prothrombotic states, increasing platelet reactivity, increasing procoagulant and decreasing anticoagulant activity, and decreasing fibrinolysis. Thus, the surgical patient who has had antiplatelet agents withdrawn is at great thrombotic risk.
There is no bridging agent for antiplatelet medications analogous to the heparins for warfarin. This would be a short-acting, inexpensive, outpatient antiplatelet agent, and it would seem that NSAIDs and cyclooxgenase-2 inhibitors might fit the bill, but they all increase MI risk. 47
So for high-risk patients, the surgeon’s choice is to withdraw antiplatelet agents and risk thrombosis, or to continue antiplatelet agents and risk bleeding. There are many good reasons to keep patients on antiplatelet agents, and the question of how to operate safely is major, timely, and unanswered. Although keeping patients on aspirin does not seem to increase operative mortality, studies do not include colectomies. 48 Bleeding is increased as expected, but not reoperation or death. Reoperation and need for transfusion are shown to increase in patients who have coronary artery bypass grafting on aspirin. 49 The literature offers little guidance on whether and when to operate in patients on antiplatelet agents, but the proliferation of percutaneous coronary interventions (PCIs) is forcing surgeons to make this decision daily, usually in favor of operating on aspirin. Operating on clopidogrel is even more uncharted territory.
ACC/AHA guidelines for noncardiac surgery in patients with PCIs include: (1) for balloon angioplasty, wait 2 weeks if possible, then operate on aspirin; (2) for a bare-metal stent, wait 30 to 45 days, then operate on aspirin; and (3) for a drug-eluting stent, wait 1 year, then stop clopidogrel for 7 to 10 days and operate on aspirin. 35 The key questions for the surgeon, still unanswered by the literature or by these guidelines, are how to treat the patient who needs an emergent or urgent operation within these “wait” periods. One would typically not, for example, want a patient with colon cancer who received a drug-eluting stent 3 months ago to wait 9 months for operation. Surgical judgment here must take surgeon and patient into dangerous and largely uncharted territory.
The only guideline is to stop antiplatelet medications when the risk of bleeding exceeds the risk of thrombosis, but continue the medications when the risk of thrombosis exceeds the risk of bleeding. 46 Because neither of these risks is quantifiable for a given patient, and the consequences of either complication can be serious, this gray area is a new and fertile source of litigation today. Clear notes that show understanding and rational judgment should protect the surgeon, whatever actual reverses the patient may experience. It also behooves the surgeon to watch his or her inbox for new guidelines, which become de facto standards of care within months of publication. The surgeon may consider consulting the patient’s cardiologist or primary care physician to discuss the optimal timing for holding and resuming the patient’s antiplatelet medication.

Patients on Steroids
Patients on exogenous steroids having an anorectal operation should stay on their daily dose throughout the day of operation, and not take any extra. For major stress such as a colon operation, a common recommendation is 100 mg hydrocortisone or 20 mg Solu-Medrol IV at the time of operation, followed by a 1 to 2 day postoperative taper. 50 However, are stress dose steroids needed at all? A systematic review of the subject indicated that these are not needed: patients on therapeutic steroids should just take their daily dose, whereas patients with known primary hypothalamic-pituitary-adrenal axis insufficiency should receive supplemental steroids. There is no clinical role for a preoperative adrenocorticotropic hormone (ACTH) stimulation test. 51 When glucocorticoid supplementation is needed, there is no consensus as to which glucocorticoid preparation—hydrocortisone, methylprednisolone, dexamethasone, etc.—is best. 52

Patients With Allergies
In a critical review of allergic reactions in 100 patients, in 73% of cases, the suspected agent was wrong, and clinical suspicions were correct in only 7%. When it is critical to know the truth about an allergy, patients in the elective setting may be referred for testing. 53 The surgeon’s most common question is about penicillin allergy in a patient who is due a preoperative dose of cephalosporin for SSI. A piece of practical advice is if the history is consistent with immunoglobulin-E–mediated anaphylaxis (airway edema, facial edema, or urticaria, the last meaning itchy welts, not just a rash), then avoid cephalosporins. Otherwise (as in the case of a maculopapular rash or a delayed rash), use a cephalosporin. 54

Elderly Patients
The morbidity and mortality of major operations increase with increasing age. 55 Although many articles indicate that major colorectal operations can be performed safely on the elderly, 56 octogenarians have higher rates of major complications after operation in all areas, and are more likely to die from these complications. 57 Aging is characterized by loss of physiologic reserve in all areas. Faced with an elderly patient with a relative indication for operation—and all indications, even malignancy, become relative at some level of risk—the surgeon must answer the question of whether to operate, and what operation to do.

Malnourished Patients
Addressing the nutritional status of the patient before an elective procedure is an often overlooked, but critical part of the preoperative workup. Albumin and prealbumin levels should be measured if there is concern for malnutrition based on low body mass index. A large, multicenter study from tertiary care veterans affairs hospitals showed that increased 30-day morbidity and mortality after noncardiac surgery was associated with decreased preoperative albumin levels. 58 In this study, low serum albumin (<3.5 g/dL) was an independent predictor of morbidity and mortality in this diverse population of patients. Low preoperative albumin was shown to be a risk factor for anastomotic leak and postoperative intra-abdominal sepsis in patients who underwent colorectal surgery. 59, 60
In addition to measuring serum albumin and prealbumin, several screening tools have been developed to assess patients who are at risk for malnutrition, including the nutrition risk index and the nutrition risk score. There is a correlation between being identified as “at risk” by these screening assessments and the development of complications after gastrointestinal surgery. 61 Elective operations should be delayed, when possible, if the patient is malnourished. Although it may take at least a month to reverse a patient’s malnutrition, elective operations should be deferred until the patient is nutritionally replete. Appropriate referral to a nutritionist is important for patient education for improved dietary choices and nutritional supplementation. In extreme cases, patients can be admitted before elective procedures for enteral feeding via nasoenteric feeding tube. Parenteral nutrition is also an option; however, this should be avoided if at all possible because of its known association with infectious complications. 62

Prophylaxis Against Common Problems

Surgical Site Infection Prophylaxis
SSI is an often discussed problem, responsible for $10 billion annual cost, an average 7 extra days in the hospital, and much heartache for patients, who need drainages and wound care, and surgeons and hospitals, who may not be paid for the extra work these sometimes preventable complications entail. 63
Anorectal operations essentially never lead to infection, both because wounds are left open—an extreme demonstration of the virtues of the open wound, the anal open wound is showered with stool, yet never infected—and because of an excellent blood supply. There is no role for antibiotics or other prophylactic measures in anorectal operations. Anorectal operations are often classified as either clean-contaminated or contaminated, but the infection rates that apply to those classifications certainly do not apply. Anorectal operations belong in a separate category of orificial operations, along with procedures in the mouth and vagina, all of which have low SSI rates.
Abdominal colorectal operations are mostly either clean-contaminated, with an expected 10% infection rate (an underestimate of the actual rate, because this category is dominated by the laparoscopic cholecystectomy), and contaminated, with an expected 18% SSI rate. Intrinsic, patient risk factors include age, nutritional status, diabetes, smoking, obesity, remote infections, endogenous (mucosal) microorganisms, immune alterations, and severity of illness. Extrinsic, iatrogenic, or nosocomial risk factors include preoperative hospitalization, scrub type and duration, preoperative shower, hair removal, skin preparation, surgical attire, sterile draping, surgical technique, duration of operation, antibiotic prophylaxis, ventilation, equipment sterilization, wound class, body temperature, and drains.
Most aspects of the preoperative routine are currently under scrutiny. Plastic adhesive drapes, whether or not impregnated with iodine, do not decrease infection rates, despite their intuitive appeal. 64 Hair should be clipped in preference to shaving, and certain extremists (present authors included) just leave all hair in place. 65 Patients should be told not to shave themselves. A preoperative shower is beneficial, but between chlorhexidine, soap, and just water, it is all a wash, with no differences in the SSI rate. 66 Mechanical bowel preparation is poorly tolerated and slightly harmful, 67 although for now it remains within the standard of care, because most surgeons still employ it. 68 There is good evidence that eradicating nasal Staphylococcus aureus from patients who are chronic carriers of this bacteria using topical nasal mupirocin decreases staphylococcal infection rates. 69 A recent, well-conducted trial in clean-contaminated operations established the superiority of chlorhexidine-alcohol scrub over the traditional povidone-iodine scrub and paint. 70
Preoperative and intraoperative hypothermia is bad for SSI because of vasoconstriction (reduced oxygen tension), decreased leukocyte function, and increased bleeding and need for transfusion. 71 Hypothermia is such a clear SSI risk factor that core temperature in the recovery room after colectomy is now a SCIP quality measure. To make success more likely, apply a forced-air convection warming system in the operating room immediately preoperatively, and make discussion of warming measures part of your standard preoperative briefing for major operations.
Hyperglycemia is another clear risk factor for infection; although the literature mostly discusses postoperative glucose control (postoperative day [POD] 2 glucose >200 mg/dL doubles the infection rate after colectomy), 72 postoperative glucose control in the preoperative phase should be planned, and its initial success or failure is set up by preoperative medication management (see Diabetic Patients , earlier). Although much of the literature on perioperative glucose control comes from cardiac rather than general surgical or colorectal patients, it is likely that this information is generalizable. The focus on perioperative glucose control in colorectal surgery may increase if this becomes a SCIP quality measure. Glucose control is likely important for postoperative colorectal surgery patients; however, how tight to control glucose and for how long postoperatively should be the subject of future clinical studies.
The least controversial aspect of preoperative SSI prevention is the administration of preoperative antibiotics. Preoperative oral antibiotics are optional, but preoperative intravenous antibiotic administration within an hour before incision defines the standard of care in SSI prevention. 73 Antibiotic prophylaxis for abdominal colorectal operations is cefazolin (1.4 hour half-life) plus metronidazole to cover anaerobes, cefotetan (3.5 hour half-life), or cefoxitin (0.75 hour half-life). The dose should be increased in heavier patients; for example, larger patients get 2 g instead of 1 g cefazolin. 74 The preoperative plan should include re-dosing antibiotics if the operation lasts >4 hours or incurs >1500 mL blood loss. Ertapenem, a longer acting alternative antibiotic, does not need to be re-dosed for longer operations, and in a randomized trial, it worked better for infection prophylaxis than cefotetan. 75 Patients with penicillin allergy can still receive cephalosporins preoperatively, if the reaction to penicillin is not immunoglobulin-E–mediated (see Patients with Allergies , earlier). There is no role for postoperative antibiotic prophylaxis, 76 and no need for “coverage” of drains or tubes. If postoperative antibiotics are needed for therapeutic purposes, the surgeon should clearly document the indication and planned duration of treatment.
SSI is the most common easily reducible postoperative complication, and prophylactic measures take place almost entirely in the preoperative phase. Have the patient take a preoperative shower with tap water, consider skipping the bowel preparation, normalize glucose, make a plan for maintaining normothermia, clip hair only if needed and never shave, use nasal decontamination if your patient is a S. aureus carrier, and give the right antibiotics within an hour of incision, and use chlorhexidine instead of iodine skin preparation, and you will be practicing modern SSI prophylaxis. SSI prevention is an active field, and one should watch one’s inbox for new guidelines and devices as they appear.

Venous Thromboembolism Prophylaxis
DVT/PE is often thought of as a silent killer, because most DVTs and PEs are asymptomatic, yet 10% of untreated DVTs progress to symptomatic PE, which confers a 30% mortality. Because half of perioperative DVTs begin in the operating room, prophylaxis needs to start before the induction of anesthesia with sequential compression devices. The abdominal colorectal surgical patient is either in the moderate- or high-risk category, based on age, malignancy, obesity, smoking, immobility due to general anesthesia, and other factors. Women on either raloxifene or tamoxifen, oral contraceptives, or hormone replacement therapy have higher risk of thromboembolic events. 77 DVT can be occur in approximately 20% of patients if untreated preventively, and PE in approximately 2% to 3% of patients. 78
For operations under local anesthesia, or for anorectal operations of ≤30 minutes, no DVT/PE prophylaxis is needed. For abdominal operations, subcutaneous prophylactic UFH should be given before incision; alternatively, LMWH or fondaparinux prophylaxis, which has the same preventive value, can be started preoperatively or postoperatively. Continuing the use of sequential compression devices in the postoperative period is prudent and well tolerated by the patient.
Heparin-induced thrombocytopenia (HIT) is more common in women, more common with UFH than LMWH, and more common in surgical than medical patients. 79 It happens in 1.5% of patients exposed to heparin, and of those, 50% develop either venous or arterial thrombosis. Although this might suggest the use of LMWH as opposed to UFH heparin in a female surgical patient, the difference is small and HIT remains rare, so standard care includes giving all your patients UFH or LMWH prophylaxis on the same protocol. Unless a patient has a history of HIT, antibody screening is not recommended. 80 For patients with a history of HIT, there are alternatives such as argatroban, and hematologic consultation is prudent.
All pharmacologic regimens for DVT/PE prophylaxis increase the risk of intraoperative and postoperative bleeding, but it is rarely clinically significant, and the benefits of prophylaxis outweigh the risks. Special consideration patients like Jehovah’s Witnesses and anemic patients should still be given DVT/PE prophylaxis; as always, special considerations should be raised and documented in the informed consent process.

Catabolism Prophylaxis
Several studies recently challenged the practice of fasting (from midnight the previous day) before major operations, suggesting that instead a carbohydrate load would help prevent postoperative catabolism and insulin resistance. 81 However, preoperative oral carbohydrate supplementation did not improve subjective fatigue or length of hospital stay in a randomized trial of patients who underwent mostly colorectal resections, 82 leaving the practice of preoperative fasting intact for the present. The most recent ASA guidelines on preoperative fasting, issued December 2011, suggest waiting at least 2 hours for clear liquids and 6 hours for solids before anesthesia. 83

Nausea and/or Vomiting and Ileus Prophylaxis
Risk factors for PONV include being female, not smoking, history of PONV, history of motion sickness, use of volatile anesthetics or nitrous oxide, intraoperative opioids, dehydration, long operation, general anesthesia, and laparoscopic operation. Strategies for reducing PONV risk include opting for regional instead of general anesthesia, and starting with adequate preoperative hydration (another argument against mechanical bowel preparation). 84 Prophylactic medications against PONV are typically 5-HT 3 receptor antagonists such as ondansetron or granisetron. These are given postoperatively, but a new one with a longer half-life, palonosetron, is given preoperatively. 85 Other drugs that can be used preoperatively for PONV are dexamethasone IV, which is often combined with ondansetron at the start of operation, and the scopolamine transdermal patch, which must be started >4 hours before operation. Another new drug that compares favorably with ondansetron is aprepitant, a neurokinin-1 receptor antagonist, which is given >3 hours before beginning anesthesia. 86
Prophylaxis against postoperative ileus is inseparable from PONV prophylaxis. The preoperative drug alvimopan has been demonstrated to accelerate return of bowel function, with the potential to cut about 1 day off the average length of stay after an abdominal operation. Postoperative gum chewing may, however, have a similar effect. 87 These two very different interventions, which have not been tested against each other, represent early attempts to modify ileus. It is not clear what role they will play in next year’s colectomy routine, but it is reasonable to guess that the future holds more aggressive interventions against ileus, some of which will be preoperative. Preoperative planning for postoperative normothermia is important to limit ileus as well as SSI. 71 Because PONV and ileus are important determinants of patient satisfaction and length of hospitalization, surgeons may wish to push their colleagues in anesthesia or the preoperative clinic to risk stratify patients and apply multiple interventions to those at high risk of postoperative misery. 88

Preoperative Clinic
Like the author, most readers will not have access to a full-service preoperative clinic, but it is worth describing as a worthy goal—a way of freeing surgeons to do what they do best. Surgeons tend to rely on the primary physician, who may be ill-informed on surgical matters, or on the patient’s established specialists, who may have the same limitation, plus the handicap of single-organ system focus. An ideal preoperative clinic melds the concerns of the anesthesiologist, whose global preoperative assessment typically (in today’s practice) comes too late to make a difference, and the surgeon, whose surgical knowledge and skill typically outpace general medical knowledge. The institution of a dedicated preoperative clinic has been shown to reduce unnecessary testing (saving resources and reducing the risks due to superfluous workup), to reduce day-of-operation cancellation and delays, 89 and to enhance patient satisfaction through less fragmented communication. 90 The preoperative clinic can be staffed by primary care providers, anesthesiologists, or some combination, and it can even be run by a surgeon who has become a preoperative specialist—probably the ideal choice, but not a realistic one. Today, dedicated preoperative clinics exist in some large, urban institutions, but in principle, a preoperative clinic can be part of any hospital, primary care practice, anesthesiology group, or multispecialty group practice. Supporting itself by savings and outcome improvements rather than fees, the preoperative clinic deserves a prominent place in a rationally organized health care system.

A minimalist approach to preoperative testing is appropriate. The preoperative clinic is an ideal method to gather the surgeon, anesthesiologist, and primary care provider to streamline the preoperative workup and decrease unnecessary testing. For minor (anorectal) operations, preoperative testing can almost be eliminated. For major (abdominal) operations, published guidelines for preoperative management of patients with specific conditions and on specific medications are valuable tools for risk modification, providing both clinical benefits and medico-legal protection. Major unanswered questions include the role of cardioprotective medication, the value of BNP in preoperative decision making, when to plan an operation on clopidogrel, the value of delaying operation to confirm suspected OSA, and the role of preoperative antinausea and anti-ileus medications. The surgeon’s decision to operate, choice of operation, and conduct of operation are the key determinants of outcome in most patients.


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chapter 4 Postoperative Management

Paul R. Sturrock, Justin A. Maykel

The Bottom Line

• Several physiologic changes occur in the postoperative period. A thorough understanding of these changes helps direct clinical decision making to facilitate patient recovery.
• Exclusion of nasogastric (NG) tubes and administration of early enteral feeding are safe and aid recovery of bowel function after colorectal surgery.
• Several options exist to prevent deep vein thrombosis (DVT) and should be used routinely in the appropriate patient populations.
• Surgical site infections (SSIs) can be minimized by the judicious use of appropriate perioperative antibiotics.
• Although several analgesia options exist, including patient-controlled analgesia (PCA), epidural, intravenous, and oral medications, a multimodal approach typically leads to the most successful postoperative pain control.
• Any delay in postoperative recovery impacts hospital length of stay and subsequent recovery to baseline function. enhanced recovery after surgery (ERAS) programs provide standardized, evidence-based frameworks aimed at facilitating recovery, including pain control, return of bowel function, tolerance of oral intake, and independent physical mobility.
• Patients undergoing anorectal surgical procedures benefit from standardized strategies and programs that focus on anesthetic technique, reliable postoperative analgesia, and prevention of postoperative urinary retention.
Colorectal and anorectal surgical procedures, whether performed in the elective or emergent setting, are some of the more commonly performed operations in the United States. The associated diseases are handled by a wide range of surgeons, from generalists to those who focus specifically on care of the lower gastrointestinal (GI) tract. Although these procedures range from routine day cases to complex multidisciplinary efforts, postoperative management has a major impact on patient experience, cost of care, and functional recovery. On a higher level, this recovery period and process affects hospital and public health resources, representing a potential source of heath care cost savings. This is particularly germane in the current setting of health care reform. In recent years, following guidelines born from evidence-based studies, this recovery process has been reexamined, streamlined, and often standardized. This chapter will outline specific areas that generally affect postoperative recovery, in both the inpatient and outpatient settings. Although each of these areas can be evaluated independently, they have relatively recently been combined into well-defined enhanced recovery programs, and this concept will be addressed as well.

Postoperative Physiology
After GI surgery, several physiologic changes occur that directly affect the recovery process. An understanding of these changes helps the clinician direct postoperative management.
One significant component of the stress response after surgery is the release of corticotropin releasing hormone by the hypothalamus, which causes release of adrenocorticotropic hormone (ACTH) from the anterior pituitary gland. ACTH stimulates glucocorticoid production by the adrenal gland, and the major glucocorticoid produced in humans is cortisol. Cortisol is an essential hormone for surviving physiologic stress, and there are multiple consequences of its release. Cortisol potentiates the activity of glucagon and epinephrine, leading to a systemic hyperglycemic state. After degradation of skeletal muscle, cortisol increases gluconeogenesis in the liver. Peripheral insulin resistance is induced in muscle and adipose tissue by circulating cortisol to prevent storage of glucose during times of stress. 1
Closely tied to glucocorticoid production is the inhibition of insulin release, moderated by inflammatory mediators and circulating epinephrine after surgical stress. Cortisol causes increased peripheral insulin resistance, also contributing to the hyperglycemia commonly seen postoperatively. Although this response may be beneficial after major injury, this shift in carbohydrate metabolism does not necessarily promote prompt recovery after colorectal surgery. Circulating insulin levels and diminished end organ effectiveness eventually recover, allowing the postoperative patient to return to an anabolic state with the resumption of glycolysis, glucose transport into cells, and adipose or protein synthesis. As noted, insulin resistance tends to self correct early in the postoperative period, but close monitoring of blood sugar in patients with preexisting conditions such as diabetes or infectious conditions is warranted because these patients may require doses of exogenous insulin to keep blood sugars within the normal range. Exogenous insulin administration itself, titrated for tight glycemic control, appears to modulate metabolic recovery particularly in critically ill patients and can have a major impact on morbidity and mortality during the postoperative period. 2
Although increased glucocorticoid levels are the most obvious result of ACTH release, the adrenal hormone aldosterone may have a more direct effect on fluid and electrolyte balance in the postoperative period. Aldosterone production is increased in response to ACTH and functions to increase intravascular volume by increasing renal reabsorption of sodium. This is accompanied by a proportional increase in potassium and hydrogen excretion. An excess of aldosterone can be a factor in postoperative edema, hypertension, and hypokalemia.
Perhaps the most complex component of the surgical stress response is that of the immune system. Elevated cortisol levels depress cell-mediated immunity. A delicate balance exists between proinflammatory and anti-inflammatory cytokines that guide each phase of tissue healing. These cytokines combine with eicosanoids (arachidonic acid derivatives) to mediate the inflammatory response. Eicosanoids include prostaglandins, leukotrienes, and thromboxanes that can, among their many other functions, increase blood vessel permeability, increase platelet aggregation, and decrease lymphocyte activity. The systemic balance of these agents can be modulated by the administration of ω-3 fatty acids and/or fish oil either via the enteral (i.e., use of immune-modulating enteral formulas such as Impact) or parenteral (i.e., fish oil–based lipid emulsions) routes. Recent data suggested that perioperative administration of immunonutrition, particularly in high-risk patients undergoing major surgery, results in decreased wound complications, infection rates, and hospital length of stay. 3
On a more macroscopic level, one of the most commonly encountered alterations in normal GI physiology is the occurrence of postoperative ileus (POI). Ileus is a short-term, predictable disruption of the normal propulsive GI motor activity due to nonmechanical causes. Probable mechanisms of this physiologic change include interruption of the sympathetic and/or parasympathetic pathways to the GI tract, inflammatory changes mediated over multiple pathways, and the spike in endogenous opioid levels that occurs with the use of exogenous opioids for the management of postoperative pain. During the postoperative period, intestinal motility returns first in the small intestine within hours of operation, followed by return of gastric function within 1 to 2 days and colonic motility in 3 to 5 days. 4 When the ileus persists for >5 days, it is considered abnormal or prolonged 5 and can be a result of a postoperative complication, such as infection, abscess, or adhesions.

Postoperative Management
The following sections of this chapter will address those areas that affect patient recovery. We will review the evidence-based data and outline the current best practices as they relate to the postoperative colorectal patient. Figure 4-1 summarizes the expected recovery and management timelines for routine, uncomplicated colorectal surgical patients.

Figure 4-1 Expected recovery and management timelines following routine colorectal procedures. *If an anticoagulation medication is prescribed preoperatively, time of re-initiation may vary based on postoperative bleeding risks. † Epidural catheter removal may vary based on the use of anticoagulation medications. DVT, Deep vein thrombosis; IV, intravenous; NSAIDs, nonsteroidal anti-inflammatory drugs; PCA, patient-controlled analgesia; PO, per oral; POD, postoperative day.

Fluid Management
Traditionally, patients undergoing abdominal surgery for colon or rectal resection were thought to require a significant amount of fluid replacement, both in the operating room and in the immediate postoperative period. The relative dehydration caused by a preoperative mechanical bowel preparation and overnight fast, coupled with the poorly understood insensible third space losses in the operating room, led to a philosophy that patients could not receive too much perioperative fluid. 6 Several recent trials and meta-analyses challenged this belief, launching a new paradigm for postoperative fluid administration.
Traditionally, patients receive 3.5 to 5 L of intravenous fluids on the day of their operation, followed by a resuscitative rate approximating 2 L/day, continued for the first several postoperative days (PODs). This accounts for a weight gain of between 3 and 6 kg in the postoperative period, resulting in an increase in interstitial tissue edema and possible delay in the return of GI function. 7 With the widespread use of laparoscopic surgical techniques, insensible losses are less common, and replacement fluid requirements are lower. Most anesthesiologists follow traditional measures to guide resuscitation, namely, blood pressure, heart rate, and urine output. Goal-directed intraoperative fluid administration guided by esophageal Doppler monitoring was advocated in some studies but can be expensive to implement on a widespread basis and, therefore, has not been uniformly adopted. 8 That said, Phan et al 9 published a collective review of nine prospective randomized studies in which esophageal Doppler was used to guide intraoperative fluid administration. They found that this technique resulted in an increased use of perioperative colloid fluids, reduction in time to resume full oral diet and bowel function, reduced complications after major surgery, and reduction in length of hospital stay. 9
For uncomplicated colon or rectal resections, intravenous postoperative administration of a balanced electrolyte solution is recommended only until the patient is taking fluids orally, targeting POD 1 or 2 for discontinuation. This is intimately related to a policy of early enteral feeding, detailed later in this chapter, as perioperative fluid therapy has recently received increasing interest because this strategy may influence postoperative outcomes. Patients who are not completely resuscitated may develop adverse effects ranging from minor organ dysfunction to multiorgan failure, whereas, more commonly, patients who are excessively resuscitated are at risk for pulmonary, cardiac, and GI dysfunction. The concept of “fluid restriction” was studied recently by Brandstrup et al 10 One hundred seventy-two patients were randomized to either a restricted or a standard intraoperative and postoperative intravenous fluid regimen. The restricted regimen, which aimed at maintaining preoperative body weight, resulted in significantly reduced postoperative complications, particularly in cardiovascular and tissue healing areas. 10 Lobo et al 7 also conducted a prospective randomized study that similarly evaluated a restrictive fluid policy for patients who underwent colectomy. “Standard management” (1 L normal saline [NS] + 2 L dextrose 5% in water [D5W]) was compared with salt and water restriction (0.5 L NS + 1.5 L D5W). The restricted group was found to have shorter median solid and liquid gastric emptying times, shorter median time to passage of flatus (1 day) and bowel movement (2.5 days), and shorter median hospital stay (3 days). 7 For more complicated operations, resuscitation with lactated ringers or NS solution should be continued until the patient’s hemodynamic parameters have stabilized. Transition to maintenance fluid should occur as soon as resuscitation is deemed complete, and the patient begins to mobilize fluid from the interstitial space.
Increased rates of hypotension have been observed as a result of medication-related sympathetic fiber blockage and vasodilation in patients who receive an epidural catheter to assist with postoperative pain control. This has often led to increased fluid administration to augment circulating volume. An alternative approach to counteract this vasodilation during the postoperative period is the administration of a low-dose vasopressor, which will reduce the need for excess intravenous fluids. 11 With strict guidelines regarding their use at most hospitals, infusion of vasopressors is limited to the operating room or postoperatively in a monitored setting such as the recovery room, step-down unit, or intensive care unit (depending on the resources of the particular hospital).
Patients with newly created stomas represent a subset of patients who can have some difficulty with postoperative fluid management. This is particularly true in the case of an ileostomy, which can lead to increased fluid and electrolyte losses, resulting in severe dehydration and/or electrolyte imbalance. 12 This typically occurs 3 or 4 days after surgery, when the physiologic ileus abates and bowel function and small bowel secretion return. In the event of high ostomy output (>2 L/day), water, sodium, and magnesium depletion can be prevented by replacement of water and electrolyte losses (initially via the intravenous route) and oral hypotonic fluid restriction using glucose or electrolyte solution, 13 antidiarrheals, 14, 15 and antisecretory medications, including histamine (H 2 ) blockers, proton pump inhibitors, and somatostatin analogues. 16, 17

Gastrointestinal Tract Function and Enteral Feeding
Resumption of normal oral intake is a critical component of recovery after colorectal surgery. Following age-old surgical dogma, many surgeons have felt it necessary to delay the commencement of oral intake until bowel function has returned, as indicated by passage of flatus or bowel movement. Tradition, as opposed to evidence-based medicine, led to the routine use of NG decompression to rest the GI tract. This approach was thought to protect the patient from a number of possible postoperative complications, including a pathologic (i.e., prolonged) POI, food regurgitation and aspiration, and anastomotic disruption. More recently, this rationale has been challenged, asking two questions. First, is there a benefit to routine NG tube use and maintaining patients nothing by mouth (NPO) after colorectal surgery? Second, are there benefits to early feeding after colorectal surgery?

Nasogastric Tube
Due to concerns surrounding ileus and subsequent abdominal distention, vomiting with aspiration, wound dehiscence, and anastomotic leak, the NG tube has been a standard adjunct to postoperative management. Over the past 25 years, several studies have looked at the role of NG decompression, culminating in a Cochrane review of 33 randomized, controlled trials, published in 2007. In these studies, patients were randomized to receive either a NG tube until intestinal function returned, or to receiving no tube or early tube removal (in surgery, in recovery room, or within 24 hours of surgery). Those without an NG tube experienced earlier return of bowel function ( P < 0.00001), a decrease in pulmonary complications ( P = 0.01), and decreased length of stay. Anastomotic leak was no different between groups ( P = 0.70). Only 1 in 20 patients benefited from placement of a NG tube in the postoperative period. Accordingly, routine NG tube decompression after lower GI surgery is not recommended, 18 and NG tubes, if used at all, should be removed at the conclusion of the operation.

Pharmaceutical Options
Several medications have been studied as adjuncts to speed bowel recovery. Unfortunately, most have shown no benefit, including metoclopramide, erythromycin, and neostigmine. 19 Despite these data, these medications are still used frequently—reflecting an overwhelming frustration in managing ileus, a lack of options, and an irresistible urge to prescribe medications despite proven futility.
We know GI transit slows with prolonged opioid administration as opioids affect the enteric nervous system and diminish normal coordinated GI tract movement. Peripheral µ-opioid receptor antagonists, such as alvimopan, have been studied as a means to counteract this effect with some conflicting results. Alvimopan, when administered preoperatively (before narcotic use) and up to 7 days after surgery, competes for peripheral µ-receptors without affecting analgesia. 20 Most recent studies attempted to objectify and standardize the definition of GI recovery, and GI-2 recovery is considered the resolution of POI, measured by maximum time for resolution of upper (toleration of solid food) and lower (first bowel movement) GI tract function. In a study by Ludwig et al, 21 patients who underwent major abdominal surgery were administered 12 mg of alvimopan orally 30 to 90 minutes preoperatively and twice daily postoperatively in conjunction with a standardized accelerated postoperative care pathway. Alvimopan was well tolerated and accelerated GI recovery and time to the written hospital discharge order compared with placebo (mean for alvimopan, 5.2 days; mean for placebo, 6.2 days). 21 More recent data suggested this decrease in mean hospital length of stay resulted in a cost savings of $879 to $977 for patients who received alvimopan compared with placebo. 22 A more recent multicenter international trial of 738 adult patients who underwent open bowel resection randomly received oral alvimopan or placebo after surgery. Although this trial failed to show benefit in the overall study, efficacy was seen in the subset of patients who received PCA. 23 In summary, the currently available evidence suggests safety, earlier return of normal GI function (by 12 to 24 hours), and cost savings when alvimopan is used in the inpatient setting after small or large bowel resection with anastomosis, particularly in those patients using PCA. Accordingly, its routine use should be encouraged.

Gum Chewing
Stimulative activities such as gum chewing have shown mixed results, particularly when comparing open and laparoscopic surgery. 24 Either the act of chewing or oral stimulation appears to increase vagal tone, which, in turn, may enhance motility of the GI tract. Gum chewing likely decreases time to resolution of POI, as reflected by an approximately 12 hour difference in passage of flatus and 24 hour difference in first bowel movement. This inexpensive treatment may even reduce length of hospital stay. 25 - 27 Given the relative safety of chewing gum, its low cost, and the lack of side effects associated with its use, it is reasonable to incorporate this into a postoperative recovery protocol.

Surgical Approach
A review of 12 randomized controlled trials comparing laparoscopic versus open surgery for colorectal cancer confirmed findings of less postoperative pain, decreased narcotic use, earlier return of bowel function, and shortened length of hospital stay for laparoscopic patients, likely due to decreased bowel manipulation and associated inflammation. 28 The criticism of this review was that the studies included were variable, not performed at single institutions, and were generally not controlled for diet introduction or perioperative care. The impact of laparoscopic surgery versus accelerated postoperative recovery programs was difficult to differentiate and therefore remained unclear.

Diet Initiation
Whether performed in a hand sewn or stapled fashion, a proper intestinal anastomosis should be air-tight at creation. At baseline, the GI tract produces about 7 L of fluid per day (1500 mL saliva, 2500 mL gastric secretions, 500 mL bile, 1500 mL pancreatic secretions, and 1000 mL small bowel secretions), 29 so from a practical viewpoint, the incremental increase from oral intake appears insignificant. Studies in the trauma setting attempted to evaluate the metabolic impact of early enteral nutrition by first looking at the safety and feasibility of early jejunal feeding. 30 This and other studies showed that it was safe to challenge the fresh anastomosis with enteral feeds within 24 hours after surgery. 31 - 34 Other studies showed that early feeding (typically defined as any oral caloric intake, i.e., normal diet or nutritional supplements) or any kind of tube feeding (gastric, duodenal, or jejunal) commenced within 24 hours of GI surgery facilitated GI functional recovery, decreased risk of infection, and shortened hospital stay. 35, 36 The metabolic implications of perioperative fasting remain poorly understood. New data suggested preoperative and early postoperative carbohydrate loading might facilitate metabolic recovery by modulating insulin resistance, potentially via local or systemic hormonal and peptide signaling. This practice showed a beneficial impact on POI as well in some studies, 37, 38 although there was too little evidence to recommend its routine use at this time.

Dietary Options
Certain clinical circumstances provide opportunity to consider the utility of various diets. Patients with oropharyngeal dysfunction may benefit from thickened liquids to both facilitate swallowing and prevent aspiration. Those with poor dentition may find a soft diet more appealing and comfortable. Patients with ileostomies are advised to avoid certain foods that may become lodged or impacted at the level of the stoma (e.g., mushrooms, corn, broccoli) and can rarely precipitate a bowel obstruction ( Fig. 4-2 ). This type of obstruction typically clears with stoma irrigation. Patients with a new stoma should be seen during the postoperative period by the hospital dietician and counseled regarding appropriateness of certain foods, especially as the patient makes the initial adjustment to life with a stoma. Some surgeons advocate the use of a low residue diet for the first several weeks after intestinal surgery, to theoretically avoid food impaction at an edematous, potentially narrowed anastomosis. Although theoretically possible, the development of a bowel obstruction due to food impaction at an anastomosis is extremely unlikely. These dietary restrictions often create confusion and anxiety for the patient, and should be discouraged. Some surgeons counsel patients with conditions such as partial small bowel obstruction, diverticulitis, or Crohn disease (where luminal narrowing or stricture is a concern) to maintain a low residue diet, but the literature does not support such a recommendation.

Figure 4-2 Food impaction from broccoli, at fascia proximal to ileostomy after total proctocolectomy for ulcerative colitis, shown in computed tomography (A) and illustration (B) .

Literature regarding the preoperative and intraoperative prophylaxis against postoperative nausea and vomiting (PONV) emphasizes identification of risk factors and tailoring intraoperative pharmacologic management, determined by the anesthesiologist, based on such assessment ( Table 4-1 ).
TABLE 4-1 Risk Factors for Postoperative Nausea and Vomiting Risk Factors PATIENT FACTORS ANESTHETIC FACTORS SURGICAL FACTORS Female Use of perioperative opioids Duration of surgery Nonsmoker Use of volatile anesthetics Abdominal surgery History of motion sickness or previous PONV Nitrous oxide  
PONV, Postoperative nausea and vomiting.
Modified from Le TP, Gan TJ: Update on the management of postoperative nausea and vomiting and postdischarge nausea and vomiting in ambulatory surgery. Anesthesiology Clin 28:225, 2010.
Areas in the brain and the GI tract are involved in the process of nausea and vomiting, including the chemoreceptor trigger zone in the brain (located outside the blood-brain barrier), the vestibular system, visceral afferents from the GI tract, and the cerebral cortex, all of which stimulate the central vomiting center in the brainstem. There are eight classes of antiemetic agents that may be used in prophylaxis and/or treatment ( Table 4-2 ).
TABLE 4-2 Types of Antiemetic Agents Phenothiazines Prochlorperazine, promethazine Anticholinergics Scopalamine Antihistamines Dimenhydrinate, hydroxyzine Butyrophenones Droperidol, haloperidol Corticosteroids Dexamethasone Serotonin antagonists (also known as 5-HT 3 receptor antagonists) Dolasetron, granisetron, ondansetron Neurokinin 1 agonists Aprepitant
5HT 3 , 5-Hydroxytryptamine-3.
From Wilhelm SM, Dehoome-Smith ML, Kale-Pradhan PB: Prevention of postoperative nausea and vomiting. Ann Pharmacotherapy 41:68, 2007.
Anesthesiologists generally give one to three of these drugs during surgery, based on their assessment of the number of risk factors present. Currently, there appears to be no consensus regarding a preferred drug regimen for this application.
Postoperatively, there remains no consensus of which drug or combination thereof is most suitable for the patient with these complaints. According to Le and Gan, 39 as a general rule, patients who have not previously received antiemetic prophylaxis should be given a serotonin-receptor antagonist, such as ondansetron, while patient who have already received prophylaxis should be given a rescue antiemetic from a different treatment class than the prophylactic drug or drugs. Treatment doses of 5-Hydroxy-tryptamine 3 receptor antagonists (5-HT 3 RA’s) for established PONV are generally smaller than those needed for prophylaxis. For example, although ondansetron 1 mg has been shown to be as effective as ondansetron 4 mg for antiemetic rescue, most clinicians tend to use the 4 mg dose in practice. It should also be noted that in patients who received a 5-HT 3 RA for prophylaxis, no further benefit is achieved from repeat doses in the 6 hours after the initial dose. In such cases, alternatives to 5-HT 3 RAs are recommended and include dexamethasone 2 to 4 mg, droperidol 0.625 mg, or promethazine 6.25 to 12.5 mg, although dexamethasone and transdermal scopolamine are not recommended for emetic episodes that occur more than 6 hours postoperatively, because of their longer duration of action. 39

Analgesia Options
Evidence suggests that postoperative thoracic epidural analgesia can facilitate return of GI motility, specifically when using a local anesthetic-based analgesic solution. 40, 41 It is theorized that this effect is mediated by inhibiting sympathetic outflow, decreasing the total opioid dose, and attenuating a spinal reflex inhibition of the GI tract. Contradictory to these reports, the specific benefit of epidurals in ERAS protocols is now being questioned. When studied in combination with an ERAS protocol, the addition of thoracic epidural added no clinical benefit over PCA when comparing length of stay (5.8 vs 6.2 days, thoracic epidural vs PCA; P = 0.55), total length of stay (including readmissions), pain scores, quality of life, complications, or hospital costs at any time point. 42 In the appropriate setting, thoracic epidural use appears to be a safe and reasonable option, whereas, practically speaking, its routine use falls to surgeon preference and/or prejudice and the expertise and enthusiasm of each institution’s anesthesiology department. A more in depth discussion of analgesia options can be found in Pain Management After Colorectal Surgery, later.

Early Ambulation
Early ambulation is encouraged and a key component of postoperative recovery programs, with both in-hospital (cardiac, pulmonary, vascular) and postdischarge (improved fatigue, sleep, and return to daily activities) benefits. 43
Early postoperative ambulation plays a small to negligible role in the resolution of POI, despite its usefulness in the prevention of atelectasis, pneumonia, and DVT. 44 When specifically evaluating for differences in physical activity after major abdominal surgery, Zutshi et al 45 showed that no difference in return of bowel function could be demonstrated between physical activity levels in patients managed by differing care pathways.

Deep Vein Thrombosis Prophylaxis
Patients undergoing abdominal colorectal surgery are at increased risk for postoperative DVT and subsequent pulmonary embolism (PE). Without the use of preventive measures, the overall risk of DVT has been estimated at 30% with a 3% rate of PE. 46 Early ambulation in hospitalized patients has long been considered the best prevention against venous stasis and the development of DVT, but even in patients undergoing uneventful surgery, this is often impractical in the first 24 to 48 hours. The use of compression stockings, sequential compression devices (SCDs), and chemical prophylaxis have all been advocated for use in colorectal surgical patients, either alone or in combination.
Graded compression stockings reduce the pooling of blood in the lower extremity veins when patients are nonambulatory, and increase the velocity of blood flow in these veins, theoretically reducing stasis and clot formation. Unfortunately, although these stockings may provide some benefit, they are often not well tolerated by patients due to the uncomfortably warm, tight, and itchy feeling they produce. Unlike prescription-fitted compression stockings that are customized to each individual patient, the disposable stockings are only roughly sized and can have a tourniquet effect at the top of the stocking. SCDs are better tolerated, and their episodic squeeze motion increases fibrinolytic activity and blood flow in lower extremity veins. An added advantage of SCDs in the postoperative patient is there is no increased risk of bleeding compared with chemical prophylaxis. The success of SCDs is limited by their proper application, tolerance, and usage, 47 which requires compliant patients and dedicated nursing staff. 48 Current guidelines of the American College of Chest Physicians (ACCP) recommend the use of mechanical thromboprophylaxis only in (1) moderate- to high-risk patients who are considered to be at such a high risk of bleeding that chemical prophylaxis is contraindicated, or (2) as an adjunct to chemical prophylaxis in very high-risk patients. 49
Chemical prophylaxis against venous thromboembolism (VTE), either with unfractionated heparin or low molecular weight heparin (LMWH), has become standard in the care of postoperative patients who have undergone colorectal resection. Multiple large studies reviewed the safety of unfractionated heparin in postoperative patients, and a large review demonstrated a significant decrease in both DVT and PE without an increase in bleeding complications. 50 There was no significant difference demonstrated between unfractionated heparin and LMWH in efficacy or safety. LMWH can be more conveniently dosed once a day compared with every 8 or 12 hours for unfractionated heparin. However, LMWH administration is associated with an increased cost.
Several controversies remain unsettled regarding the prevention of DVT. Every hospital should develop a written, institution-wide thromboprophylaxis policy endorsed by department heads and medical advisory boards. These typically follow the best-practice guidelines published by the ACCP and the American Society of Clinical Oncology, 49, 51 yet compliance remains far from optimal, with recent data suggesting that only 71% of at risk US surgical patients receive recommended prophylaxis. 52 Prophylaxis is ideally started before surgery and continued at least until the patient is fully ambulatory. Patients are categorized according to risk (low, moderate, high). No specific thromboprophylaxis is necessary in low-risk patients (i.e., day case anorectal) without risk factors. Moderate- and high-risk patients are routinely recommended to use prophylactic anticoagulation. A recent Cochrane review focusing on colorectal surgical patients recommended that the optimal DVT prophylaxis regimen should be a combination of graded compression stockings and either low-dose unfractionated heparin or LMWH. 53 Due to the high incidence of postdischarge DVT in certain patient populations, the duration of therapy remains controversial. Most patients are maintained on treatment until hospital discharge, but recent evidence supported extended use for 28 days in those patients at highest risk—those with major cancer resections and those with a history of DVT. 54 Although not yet listed as a best practice guideline, the extended posthospital use of heparin may be considered in the appropriate high-risk patient populations. DVT prophylaxis and compliance are, of course, major components of the Surgical Care Improvement Project (SCIP), and closely monitored by the American College of Surgeons National Surgical Quality Improvement Program. Table 4-3 outlines the practice parameters for the prevention of venous thrombosis published by the Standards Committee of the American Society of Colon and Rectal Surgeons (ASCRS) in 2006.

TABLE 4-3 Practice Parameters for the Prevention of Venous Thrombosis

Prevention of Infection

As the impact of SSIs on postoperative length of stay and overall hospital cost becomes better understood, the appropriate selection and dosing of perioperative prophylactic antibiotics has garnered more attention as a quality control measure. 55 The previously mentioned SCIP pays particular attention to appropriate perioperative antibiotic use, focusing on the following evidence-based process and outcome measures regarding infection (INF):

SCIP INF 1: Prophylactic antibiotic received within 1 hour before surgical incision
SCIP INF 2: Prophylactic antibiotic selection for surgical patients
SCIP INF 3: Prophylactic antibiotics discontinued within 24 hours after surgery end
For elective colorectal resections, current guidelines include a number of options that cover aerobic and anaerobic organisms, most of equal efficacy, which are reviewed in Chapter 3 . In the event that an operation is performed for established infection, duration and choice of antibiotics is left to the discretion of the operating surgeon. Whenever possible, antibiotics should be narrowed to cover the offending organism(s) as soon as culture results are available to prevent the development of antibiotic resistance. Despite quality measures outlining proper antibiotic use, the incidence of SSI is often underreported, and these guidelines are not universally followed. 56

Foley Catheter
Bladder catheterization is necessary for patients undergoing colorectal resection due to the length of the operation and the use of urine output as a guideline for resuscitation. Increased understanding of the frequency and severity of catheter-associated urinary tract infections has led to a recommendation to either avoid their use when possible or remove them as soon as they are no longer essential. For uncomplicated colon resections, catheters can be safely removed within the first 48 hours of surgery, with infrequent subsequent urinary retention. The most current SCIP guidelines require Foley catheter removal within 48 hours of surgery. When performing more extensive pelvic dissection such as proctectomy, a longer duration of bladder drainage has been considered necessary because traction on the pelvic nerves results in a higher likelihood of urinary retention and, therefore, these patients are excluded form the aforementioned SCIP guidelines (currently under clinical investigation). In such cases, it is routine for the catheter to remain indwelling until the third or fourth POD. Recently, a randomized trial demonstrated no significant difference in urinary retention rates between early (POD 1) and late (POD 3 or 5) catheter removal after pelvic surgery. This study was limited by its small numbers, but it raises the possibility that prolonged bladder catheterization may not be necessary. 57 A commonly held myth that urinary catheters are mandatory in the setting of postoperative epidural analgesia is largely unsubstantiated by hard data, 58 and may result in increased urinary tract infection rates and prolonged hospital length of stay. 59

Pain Management after Colorectal Surgery
Independently, appropriate and adequate postoperative pain control can relieve pain and lead to earlier mobilization, shortened hospital stay, reduced hospital costs, and increased patient satisfaction. 60 - 62 Fortunately, several reliable options exist, which include systemic analgesics (opioids, nonsteroidal anti-inflammatory drugs [NSAIDs], acetaminophen, tramadol, and neurontin) and regional techniques (neuraxial and peripheral analgesics). Although a number of safe and effective options are available, a multimodal approach is often most useful, providing concurrent administration of different classes of analgesics. 63 This approach allows each class of analgesic to inhibit pain at different sites of the pain pathway, working synergistically, and allowing the use of relatively smaller doses of each agent. The net effect results in accelerated recovery, decreased length of hospitalization, reduced dosage of each individual agent, and lower frequency and severity of side effects. 64

Patient-Controlled Analgesia
PCA is one of the most commonly utilized pain control methods after major abdominal surgery. A variety of narcotic medications, including morphine, hydromorphone, and fentanyl, can be self administered utilizing this reliable, programmable delivery system. A PCA device can be programmed for several variables, including demand (bolus) dose, lockout interval, and background infusion. Not only does PCA allow the patient to administer the pain medication “on command,” but also in “real time,” without lengthy delays between summoning the nurse and receiving medication. Pain control becomes one of the few aspects of care that remains in their direct control. Additional benefits include reduced workload for the nursing staff and reduced chance for medication errors, whereas disadvantages include short duration of intravenous opioid action (variable among agents, but as short as 8 minutes). Although some equipment-related malfunctions have been reported, the PCA device itself is relatively free of errors. 65
The incidence of opioid-related side effects from intravenous PCA is similar to other routes of administration. 66 Rare side effects, generally avoided by proper use, include nausea, vomiting, urticaria, sedation, depression of brainstem control of respiratory drive, hypotension (more common in hypovolemic patients and after rapid injection), and urinary retention. A background infusion was initially thought to improve analgesia, especially during sleep; however, studies showed that use of a background infusion only increases the analgesic dosage used and the incidence of side effects, such as respiratory depression. 67

Postoperative Epidural Analgesia
Neuraxial routes of administration include the epidural and intrathecal routes, and require coordinated care with anesthesiologists. Both local anesthetics and narcotics can be administered on an intermittent or continuous basis through a tiny polypropylene catheter (19 or 20 gauge) inserted through the skin into the epidural space, at a variety of spine levels ( Fig. 4-3 ). Simply speaking, this blocks transmission of pain signals from the peripheral sensors to the spinal cord. Although this form of analgesia is particularly efficacious in childbirth and thoracic surgery, its utility in abdominal surgery tends to be less widely accepted. Use is avoided in patients with underlying coagulopathy or those on antiplatelet or anticoagulant medication, due to the risk of spinal or epidural hematoma formation. Potential complications include infection, misplacement (due to variations in spinal anatomy or catheter migration), and malfunction.

Figure 4-3 Epidural catheter placement technique showing thoracic and lumbar level epidural (A) and epidural catheter secured to patient’s skin to prevent dislodgement (B) .
Epidural agents, including opioids and local anesthetics, can be delivered by a single injection, intermittent injections, by continuous infusion, or via a patient-controlled mechanism. When epidural opioids are used alone, they do not generally cause motor block or hypotension from sympathetic blockade. 68 An important determinant of opioid action is the drug’s degree of lipid solubility. Morphine is hydrophilic, which accounts for its slow onset of analgesia, long duration of action, its ability to provide analgesia over a wide dermatomal distribution, and the concurrent risk for respiratory depression (a result of rostral migration to the brain). Fentanyl is lipophilic, which accounts for its fast onset and short duration of action, its ability to provide segmental analgesia, and its limited risk of late respiratory depression. 69 Compared with a local anesthetic or opioid alone, a local anesthetic-opioid combination infusion provides advantages, including superior postoperative analgesia, limited regression of sensory block, and possibly decreased dose of local anesthetic administered. 70 The use of perioperative epidural anesthesia and analgesia, especially with a local anesthetic-based analgesic solution, can attenuate the pathophysiologic response to surgery and may be associated with a reduction in morbidity and mortality compared with analgesia with systemic (opioid) agents. 71 When opioid agents are used in the epidural, they may delay resolution of POI compared with those patients in whom local anesthesia alone is used.
Many medication-related side effects can occur with use of postoperative epidural analgesia. In general, an Acute Pain Service (or designated committee in hospitals without dedicated Acute Pain Service) sets institutional protocols, including neurologic monitoring, treatment of side effects, and physician notification of critical parameters. These guidelines allow nursing staff to closely monitor patients. Hypotension, typically a result of blockage of sympathetic fibers, can be treated by decreasing the overall dose of local anesthetic administered or by infusing an opioid alone. Lower extremity motor block (2%-3% incidence) resolves in most cases after decreasing the concentration of local anesthetics. 72 Respiratory depression is dose dependent and rare (0.1%-0.9% incidence), and is more commonly associated with the use of hydrophilic agents, increasing age, and concomitant use of systemic opioids or sedatives. 73 Urinary retention, a result of decreasing detrusor urinary contractility, has been seen in as high as 70% to 80% of patients, 74 so most surgeons leave a urinary catheter in place until the epidural catheter has been removed. Although this practice makes logical sense, particularly in elderly men with preexisting urinary dysfunction, this practice is largely unsupported by the literature. 58

Oral Narcotics
Regardless of the initial route of postoperative pain medication administration, virtually all patients are transitioned to oral analgesics once they are able to tolerate oral liquids in anticipation of discharge to home. Common oral narcotics include oxycodone, hydrocodone, codeine, morphine, and hydromorphone. Although this transition is often straightforward in narcotic-naive patients, patients with chronic pain or a high narcotic tolerance can present a challenge when switching delivery route or type of narcotic medication. Table 4-4 is a useful reference guide that provides equianalgesic doses of commonly prescribed narcotic pain medications. 75 This particular guideline also provides a tool that accounts for dose modifications that aim to avoid significant over- or under-dosing.
TABLE 4-4 Opioid Analgesic Conversion Chart ORAL/RECTAL DOSE (mg) ANALGESIC PARENTERAL DOSE (mg) 150 Codeine 50 150 Tramadol * – 15 Hydrocodone – 15 Morphine 5 10 Oxycodone – 3 Hydromorphone 1 – Fentanyl 0.05 Calculation Formula To convert from one opioid or route of administration to another opioid or route of administration, use the following formula: Adjusting for Cross Tolerance If the patient has not used the new opioid, in order to avoid side effects of the new medication, you may consider adjusting the dose as follows, based on level of current pain. Poor pain control 7-10/10 100% conversion Moderate pain control 3-6/10 75% conversion Excellent pain control 0-2/10 50% conversion
Courtesy Department of Pharmacy and Therapeutics and Palliative Care Medicine, University of Massachusetts Memorial Medical Center.
* Maxium daily dose depends on renal function.

Nonsteroidal Anti-inflammatory Drugs
Mild to moderate postoperative pain can often be managed with NSAIDs, unless there is a contraindication to these agents. NSAIDs exert their analgesic effect through inhibition of cyclooxygenase (COX) and synthesis of prostaglandins, which are important mediators of nociception. As an adjunct to systemic or neuraxial opioid analgesia, NSAIDs can improve postoperative analgesia and reduce opioid requirements by up to 50%. 76 The most commonly used NSAIDs are ibuprofen, naproxen, and diclofenac, which are typically given orally on a regular schedule (i.e., naproxen 500 mg PO every 12 hours). Ketorolac is the only NSAID approved for parenteral use, and so is particularly useful in the postoperative period before the patient is able to take oral medication. Administration of ketorolac can reduce narcotic consumption by 25% to 45%, and indirectly lower opioid side effects such as ileus, nausea, and vomiting. 77 After a loading dose of 30 mg IV, 15 to 30 mg IV every 6 hours can provide excellent analgesia or supplement other analgesic techniques. Dosing should be adjusted downwards (15 mg) in the elderly or patients with renal dysfunction. Despite the analgesic benefits, perioperative use of NSAIDs is associated with a number of rare side effects, including decreased hemostasis, renal dysfunction, GI ulceration and/or hemorrhage, and effects on bone healing and osteogenesis. Many of these side effects are related to inhibition of COX and formation of prostaglandins and occur infrequently, so their routine use in appropriate patients is not precluded.

Local Anesthesia
Early studies provided evidence for the benefit of preemptive infiltration of local anesthesia before incision. 78 The administration of local anesthesia before skin incision, by preemptively blocking nociceptors, leads to reduced conduction of pain signals to the central nervous system and a resultant improvement of postoperative pain control. Some randomized trials showed that local anesthetic injection around incision sites reduces postoperative somatic pain. 78, 79 Theoretically, the mechanism of action includes inhibition of nerve transmission, reduction of neurogenic inflammation, and direct inhibition of the cellular inflammatory response. The addition of deep, subfascial infiltration, serving as a regional nerve block, has been shown to be efficacious as well. 80 Although the practice of administering local anesthesia is supported by the existing literature, routine implementation is not widely followed and administration at most institutions remains surgeon-specific.
Originally utilized in thoracic surgery, the ON-Q Pain Relief System is a method of delivering continuous wound infiltration with a solution of local anesthetic through an indwelling irrigation apparatus that serves as a useful adjunct to postoperative analgesia ( Fig. 4-4 ). The system consists of a 20-gauge soaker catheter attached to an elastomeric balloon pump that is capable of infusing a set volume of local anesthetic into the surgical site for 2 to 5 days. Studies in open inguinal hernia surgery showed this system to be safe and effective while reducing narcotic usage and pain, with no apparent increase in the risk of infection or complication. 81 Similar findings were reported in laparoscopic surgery, 82 whereas more recent evaluations comparing local anesthetic versus saline infusion in bariatric 83 and colorectal 84 patients failed to demonstrate any significant clinical advantage over current best practice. This product remains under clinical study and is not used routinely at our institution, but provides the surgeon with another safe option for postoperative analgesia.

Figure 4-4 On-Q pump. When used for an abdominal incision, via separate entry point, local anesthesia is delivered continuously along either side of the incision.

The prophylactic placement of closed suction drains after colorectal surgery remains controversial. Although several randomized trials reported conflicting results, a Cochrane analysis was performed in 2004. 85 The authors evaluated 6 randomized controlled studies, with 1140 patients, showing no difference in mortality, anastomotic dehiscence, wound infection, reintervention rate, or extra-abdominal complications comparing patients with and without drains. That said, drains are still commonly used, particularly after rectal dissection, and are typically left in place for several days until confident that the output volume has decreased and character is not purulent, enteric, bloody, or chylous. There is no evidence to suggest that prophylactic antibiotics decrease drain-related infection rates.

Postoperative Management of Preoperative Medications
Several preoperative medications are resumed during the postoperative period, and there are a few that deserve special mention. Timing for resumption of therapeutic anticoagulation, perioperative management of long-term steroids, and the use of antiulcer medications can be challenging.

The resumption of therapeutic anticoagulation after major abdominal surgery commonly poses a difficult decision for the surgeon, striking a balance between the risk of a thrombembolic or cardiac event and the risk of postoperative hemorrhage. Of course, surgeons tend to perceive this balance differently than other physicians such as cardiologists and primary care physicians. There is no universally accepted bridging regimen tailored to the patient’s thromboembolic risk. The highest risk patients are those with artificial heart valves or a known hypercoagulable state who require long-term anticoagulation with warfarin. In patients who undergo major abdominal surgery, anticoagulation with intravenous heparin is preferred and can be resumed within 12 hours of surgery, provided the patients have adequate hemostasis and stable hemodynamics. 86 Heparin is often administered by protocol, but it is essential to check the partial thromboplastin time every 6 hours to avoid supratherapeutic levels, which could lead to increased bleeding complications. The use of LMWH to bridge anticoagulation is another option, yet there is no routine method available to monitor the level of systemic anticoagulation using LMWH. Warfarin can be restarted once the patient is able to take oral liquids, and the international normalized ratio (INR) should be monitored to be sure a therapeutic level is reached before discontinuing heparin. Adjustment of preoperative dosages must be considered, and the INR can be affected by alterations in nutrition and the use of perioperative antibiotics. Postdischarge management typically shifts to either the primary care physician or a dedicated anticoagulation clinic. Lower risk patients (i.e., patients undergoing anorectal fistula surgery and anticoagulated for atrial fibrillation) who are on warfarin may simply restart warfarin when they resume an oral diet. Likewise, patients on antiplatelet therapy with aspirin or clopidogrel (Plavix) may be restarted on these medications as directed by the prescribing physician, typically the patient’s primary physician, cardiologist, neurologist, or cardiovascular surgeon.

A common indication for operating on patients with inflammatory bowel disease is long-term steroid dependence. Termed “steroid refractory disease,” this presents a host of challenges to the operating surgeon during the perioperative period. Additionally, patients who are on long-term steroid therapy for unrelated systemic diseases may require elective or emergent colorectal surgery. Long-term steroid treatment can result in suppression of autogenous steroid production due to biofeedback inhibition of the adrenal glands. Abrupt discontinuation of steroids in the postoperative period, coupled with the stress of surgery, is likely to cause adrenal insufficiency, manifested by hypotension, weakness, lethargy, and electrolyte abnormalities. Although a full discussion of adrenal insufficiency is beyond the scope of this chapter, a surgeon must be aware of its symptoms, as they can be confused for other more common postoperative complications. To reduce the chance of adrenal insufficiency in steroid-dependent patients, a “stress dose” of steroids (typically 100 mg IV hydrocortisone) is given just before surgery and every 8 hours for the first 24 hours postoperatively. Although no well-established guidelines exist, an acceptable approach is to then taper this dose to 50 mg every 8 hours for 24 hours and then to 25 mg every 8 hours; input from the prescribing physician or hospital endocrinologist may be helpful. In patients who have been on steroids for only a short period of time (<1 month), the taper can usually be discontinued after 24 hours at the 25 mg dose. In those who have been on long-term steroids, a transition to oral prednisone is made once they are taking oral liquids, and transitioned to a slow taper over the course of several weeks. The prednisone dose is decreased by 5 mg/week until it can be discontinued. If at any time the patient develops symptoms of adrenal insufficiency secondary to withdrawal, the dose is raised back up to the previous level, and an even slower taper is begun. Some cases will require consultation with an experienced endocrinologist to provide the best taper regimen for more complicated patients.

Stress Ulcer Prophylaxis
The use of postoperative NG decompression combined with a prolonged period of bowel rest has historically led to an increased risk of gastric ulcer formation. This may be secondary to physical trauma to the gastric mucosa caused by the NG tube, or related to surgical stress, hence the term “stress ulcer.” The practice of routinely medicating patients with either H 2 antagonists or, more recently, proton pump inhibitors has been largely abandoned with the advent of early postoperative feeding and elimination of routine NG decompression. This practice is no longer supported based on the extremely low rates of clinically important bleeding in non-intensive care unit patients. 87 In patients who are already on an acid-reducing medication, these agents are continued in the postoperative period, either in the oral or intravenous form. In patients who were not previously on any acid suppression medication but require a postoperative NG tube, either an intravenous H 2 antagonist or proton pump inhibitor is recommended to decrease gastric acidity and volume only for the duration of NG decompression. 88 Additionally, patients on perioperative steroid therapy are more susceptible to gastric ulceration and should have at least an H 2 antagonist prescribed until they are reliably taking an oral diet. The use of antiulcer medications for postoperative patients in an intensive care unit setting is a much more complicated topic, and is often determined by institutional protocol (for patients with respiratory failure on the ventilator, GI bleed, active infection, NPO) or individual physician preference.

Perioperative β-blockade has been shown to decrease cardiovascular risk in patients undergoing vascular surgery with cardiac ischemia 89 and has become a Class I recommendation in this patient population. 90 Routine use has been expanded to include patients with untreated hypertension, coronary artery disease, or risk factors for coronary artery disease. More recently, use has been expanded to patient populations never shown to derive benefit from β-blockade, including nonvascular patients and patients with low to moderate cardiovascular risk. 91 The most current prospective data suggests that widespread use may increase intraoperative complications and postoperative stroke and mortality rates. 92
In the colorectal patient population, the only Class I recommendation from the American College of Cardiology Foundation/American Heart Association is the continuation of β-blockade in the perioperative period in those patients already taking them preoperatively. 93 This recommendation has even been incorporated into the SCIP outcome measures given its importance: SCIP Card 2: Surgical patients on a β-blocker before arrival receive a β-blocker during the perioperative period.
It is widely accepted that patients undergoing either abdominal or anorectal surgical procedures should take their oral β-blocker the morning of surgery. After elective colorectal resection, patients are continued on their same oral medication and dosage on POD 1. For any procedure where the patient is kept NPO postoperatively or has a NG tube in place, intravenous β-blockade may be substituted until oral diet is resumed. To prevent associated complications, these medications are ordered with hold parameters for bradycardia or hypotension. Depending on institutional protocols, this may require the patient to be on telemetry monitoring for the duration of intravenous medication use (as at our home institution). For any patients with labile blood pressure or heart rate, these medications should be cautiously continued with consultation from a cardiologist.

Anorectal Surgery

Immediate Recovery and Anesthetic Technique
Combination anesthesia and the concurrent use of multiple agents and delivery routes to achieve improved efficacy for anorectal procedures was described as far back as 1963 when Alexander et al 94 reported the administration of intravenous barbiturate before performing perianal block with local anesthetic. Widespread adoption of this technique did not occur for many years, as many surgeons preferred operating with the patient in the prone position. With concerns regarding airway protection, general anesthesia via orotracheal intubation was the standard approach. Recently, several studies reported on the safety of combined intravenous sedation or local anesthetic, regardless of patient positioning (prone vs lithotomy), with conversion rates to general anesthesia as low as 0.4% to 1%. 95, 96 Sun et al 95 described a technique of delivering anorectal anesthesia, considered monitored anesthesia care or monitored intravenous anesthesia, which was developed in a collaborative fashion by anesthesiologists and surgeons. It consists of the initial administration of an intravenous benzodiazepine (typically midazolam) in the holding area, followed by a careful infusion of propofol and ketamine in the operating room. After the local anesthetic is injected, a decreased amount of systemic anesthesia is required for the remainder of the procedure. Given the short half-life of propofol and ketamine, patients are often completely awake at the conclusion of the operation, obviating the need for observation in the postanesthesia care unit in most cases. This decreases utilization of hospital resources and achieves a shorter postoperative stay for patients.

Analgesia Options
The management of postoperative pain after abdominal surgery has been discussed. Here we will highlight options specific to anorectal surgery.

Local Block
Local anesthetic agents can be delivered to provide a block of the pain fibers supplying the anorectal region. Although several anesthetic techniques exist for anorectal surgery, most practitioners settle on the one that works for them. Not only should this produce adequate analgesia for the procedure itself, but serves to preemptively block the pain fibers (see Local Anesthesia, earlier), relaxes the sphincter complex for the procedure, and provides pain relief for the first 6 to 12 hours after the procedure. 97 A combination of 1% lidocaine and 0.5% bupivacaine provides both immediate and longer term control, whereas the addition of epinephrine can help prevent local bleeding and potentiate a longer analgesic effect. 98 Figure 4-5 illustrates the technique of perianal block prior to anorectal surgery.

Figure 4-5 Perianal block technique. A, Using a 10 cc syringe and 22 gauge needle, the anesthetic agents are delilvered circumferentially around the anus, just outside the external sphincter in the ischiorectal fat. B, The injection is delivered parallel to the anal canal throughout the length of the 1.5 inch needle, infiltrating deeply to the level of the levator muscles.

Oral Analgesics
Once the effect of the local anesthetics used at the time of surgery wears off, patients are transitioned to a variety of orally administered agents. Mild to moderate postoperative pain can often be managed with a NSAID, unless there is a contraindication to its use. NSAIDs exert their analgesic effect through the inhibition of COX and synthesis of prostaglandins. NSAIDs can improve postoperative analgesia and reduce opioid requirements by up to 50%, 99 but are most commonly used in conjunction with oral opioids. The most commonly used NSAIDs are ibuprofen, naproxen, and diclofenac, which are typically given orally. Ketorolac is the only NSAID approved for parenteral use, and can be administered at the conclusion of the case, in the recovery room, or continued for patients admitted postoperatively, as discussed earlier together with potential side effects of this medication class. Although more expensive than the generic alternatives, this medication can be continued in its oral form after hospital discharge, on a scheduled regimen for up to 5 days. This approach of administering NSAIDs can allow a decreased overall usage of narcotics by providing a baseline level of pain control, whereas narcotics can be used on a as needed basis for breakthrough pain.
Oral opioids such as hydrocodone, oxycodone, and codeine are commonly combined with aspirin or acetaminophen (i.e., Percocet, Vicodin, or Percodan). These are typically administered on a as needed basis, with decreasing requirements over time. Hydrocodone is considered a slightly weaker option compared with oxycodone, but can be conveniently refilled by telephone in pharmacies in the United States. Oxycontin, an oxycodone oral preparation formulated for equal opioid potency and sustained release requiring less frequent dosing, provides reliable pain control, but is rarely utilized due to patient dependence issues and “profit potential” from recreational and street traffickers. More recently, medications such as gabapentin (Neurontin) have been added to the postoperative armamentarium, 100 particularly for neuropathic pain. 101 Routine use is limited by delayed onset, side effects (including dizziness, drowsiness, and peripheral edema), expense, and animal studies suggesting increased incidence of adenocarcinomas, 102 and is not recommended because there are no good data supporting its use in the routine postoperative patient. Oral medications that are considered non-narcotic and, therefore, may avoid postoperative constipation, include tramadol (Ultram). Tramadol, although considered a nonopioid analgesic, has some opioid-like effects, with weak µ-agonist activity. The advantages of tramadol for postoperative analgesia include the relative lack of respiratory depression, major organ toxicity, depression of GI motility, and a low potential for abuse. Tramadol should be used with caution in patients with seizures or increased intracranial pressure and in those taking monoamine oxidase inhibitors. Oral benzodiazepines such as diazepam can be added as well. The sedative effects are particularly helpful when taken at bedtime, whereas the skeletal muscle relaxant effects helps relieve the sphincter spasm often associated with anorectal procedures. Although not considered oral preparations, some opioids can be administered as sublingual, rectal, or transdermal preparations. Of course, rectal options are limited after anorectal surgery; however, transdermal patches (such as fentanyl) provide a reliable, steady delivery option that continues over 72 hours. The optimal approach takes advantage of the various options, scheduling routine NSAIDs coupled with as needed narcotic agents.

Fluids and Urinary Retention
The most significant immediate postoperative complication after anorectal surgery is urinary retention. Overall incidence is estimated to be 20%, and is most commonly seen after hemorrhoidectomy. 103, 104 Due to the short duration of most anorectal procedures, bladder catheterization is rarely necessary and thus is not routinely performed. As the trend toward ambulatory anorectal surgery has evolved, treating urinary retention with bladder catheterization has become more difficult. Therefore, more focus has been placed recently on the prevention of urinary retention, rather than on symptomatic treatment.
The etiology of urinary retention after anorectal surgery is hypothesized to be caused by anal canal swelling and pain, inhibition of detrusor muscle activity, and contraction of the bladder neck (possibly in combination with pelvic floor muscle spasm leading to bladder outlet obstruction). 105 Attempts to prevent urinary retention using various medications were largely disappointing. Bethanacol, a parasympathomimetic with efficacy in treating cases of urinary retention, was not shown to be effective as a prophylactic medication before anorectal surgery. 106 Alpha-adrenergic antagonists were used to blunt stimulation resulting from the acute pain response, but there was no clear reduction in the rate of urinary retention. 107
Minimization of perioperative fluid administration after anorectal surgery, by decreasing the distention of the urinary bladder, was evaluated and shown to be an effective approach to reduce postoperative urinary retention. 108, 109 Multiple retrospective studies demonstrated increased rates of urinary retention with higher levels of intraoperative fluid volume. Most recently, intraoperative intravenous fluid restriction to volumes <600 mL was linked to a lower rate of urinary retention in patients who underwent spinal anesthesia. 110 Therefore, intraoperative intravenous fluid should be limited to ≤500 mL whenever possible, particularly by discontinuing intravenous fluids as soon as the patient is awakened from the procedure.

Restoration of Normal Bowel Function
A vital component in the postoperative management of patients after anorectal surgery, and one that causes particular concern and anxiety for patients, is the resumption of normal bowel movements. This can be particularly challenging given that many patients undergo anorectal surgery for conditions related to constipation or poor bowel habits. Further complicating the situation is that narcotics used to control postoperative pain can cause constipation as a side effect. In addition, severe postoperative anorectal pain can be a psychological deterrent to having a bowel movement.
The use of a soluble fiber such as psyllium husk is the first-line treatment to modify stool texture in the postoperative period. Currently, several options are widely available over-the-counter as soluble powders, capsules, chewable tablets, and crackers. Patients are encouraged to supplement with fiber before surgery so they can find an effective and palatable option that can be continued postoperatively. Fiber (when coupled with adequate water intake) is more effective than laxatives for maintaining consistently bulked, soft stools.
Unfortunately, even strict adherence to a fiber supplementation regimen may not be enough to modify stool texture and provide for regular bowel movements in some patients. For these patients, adjuncts such as stool softeners or laxatives can be added. Docusate sodium works by reducing the surface tension of the oil-water interface of the stool, resulting in better hydrated, softer stools, but is minimally effective in this scenario. When patients fail to have a bowel movement for several days after surgery, an oral laxative such as senna, oral bisacodyl, Miralax, or milk of magnesia (MOM) can promote the return of bowel function and avoid impaction. These medications should be used judiciously—only in cases of significant constipation—because long-term use can lead to a tolerance and need for increasing doses.
A reliable protocol for postoperative management includes administration of a daily psyllium powder supplement, reserving MOM as a “rescue” if 1 to 2 days pass without bowel function. If the MOM fails to stimulate a bowel movement, magnesium citrate is a safe over-the-counter option as well. The ultimate goal is to maintain soft, bulked, regular stools to avoid anal canal trauma or impaction.

Postoperative Clinical Pathways
ERAS programs are evolving as a standardized approach in management of patients after colorectal surgery. These programs combine the aspects of care that have been outlined in this chapter, consolidated and standardized into an evidence-based patient care protocol. Otherwise known as “fast track surgery,” these programs aim to decrease postoperative complications and shorten hospital stay while decreasing recovery-related costs. These benefits extend to improving patient experience and saving overall health care costs. Although the incremental costs of one additional day of hospitalization are not large, the ability to free a hospital bed for a new patient allows for increased numbers of patients to obtain access to busy hospitals. This must be balanced by maintaining a low hospital readmission rate.
These programs target preoperative, intraoperative, and postoperative practices. This chapter focused on the postoperative measures, including analgesia options, early mobilization, early enteral feeding, avoidance of NG tubes, infection, DVT prevention, and early removal of urinary catheters. In a recent meta-analysis of randomized trials, ERAS programs were shown to provide superior outcomes compared with traditional perioperative care. 111 More recently, reduced morbidity and hospital length of stay have been realized, specifically focusing on patients undergoing elective colon and rectal surgery. 112 When developing a program, it is imperative to consider factors outside of the recovery program that delay hospital discharge, including protocol compliance, organizational interventions, and discharge delays (both social and institutional) as these may postpone patients from physically leaving the hospital. 113 In 2009, a consensus review was performed to study ERAS programs after colorectal surgery, 114 providing a framework for developing and implementing a program at other institutions. A list of consensus guidelines for the various components of an ERAS program is presented in Table 4-5 .
TABLE 4-5 Consensus Guidelines ITEM GUIDELINE Preadmission information and counseling Patients should receive oral and written preadmission information describing what will happen during hospitalization, what they should expect, and what their role is in the recovery process. Preoperative bowel preparation Patients undergoing elective colonic resection above the peritoneal reflection should not receive routine oral bowel preparation (Grade A). Bowel preparation may be considered in patients scheduled for low rectal resection where a diverting stoma is planned. Preoperative fasting and preoperative carbohydrate loading The duration of preoperative fasting should be 2 h for liquids and 6 h for solids (Grade A). Patients should receive carbohydrate loading preoperatively (Grade A). Preanesthetic medication Patients should not receive medications known to cause long-term sedation, from midnight before surgery. Short-acting medications given to facilitate insertion of epidural catheter are acceptable (Grade A). Prophylaxis against thromboembolism The preferred methods for prophylaxis in patients undergoing elective colorectal surgery are subcutaneous low-dose unfractionated heparin or subcutaneous low-molecular-weight heparin (Grade A). Antimicrobial prophylaxis Patients undergoing colorectal resection should receive single-dose antibiotic prophylaxis against both anaerobes and aerobes about 1 h before surgery (Grade A). Standard anesthetic protocol Long-acting opioids should be avoided in patients undergoing anesthesia. Patients should receive a midthoracic epidural commenced preoperatively and containing local anesthetic in combination with a low-dose opioid (grade A). Preventing and treating postoperative nausea and vomiting Prevention of postoperative nausea and vomiting should be induced if ≥2 risk factors are present. Treatment should be immediate, with combinations of the drugs discussed. Laparoscopy-assisted surgery Laparoscopic colonic resection is recommended if the surgeon or department is proficient with the technique and prospectively validated outcomes show at least equivalence to open surgery (Grade A). Surgical incisions A midline or transverse laparotomy incision of minimal length should be used for patients undergoing elective colorectal resection. Nasogastric intubation Nasogastric tubes should not be used routinely in the postoperative period (Grade A). They should be inserted if ileus develops. Preventing intraoperative hypothermia Intraoperative maintenance of normothermia with an upper body forced-air heating cover should be used routinely (Grade A). Perioperative fluid management Intraoperative and postoperative fluid restriction in major colonic surgery with avoidance of hypovolemia is safe (Grade A). Compared with excessive fluid regiments, normovolemic regimens in major colonic surgery lead to more favorable outcomes (Grade A). Intraoperative goal-directed therapy (e.g., with transesophageal Doppler monitoring) is superior to a nonprotocol-based standard with respect to outcome and/or Grade A and should be considered on an individual basis.
Courtesy Lassen K, Soop M, Nygren J et al: Enhanced Recovery After Surgery Group: Consensus review of optimal perioperative care in colorectal surgery: Enhanced Recovery After Surgery Group recommendations. Arch Surg 144:961, 2009.

All ERAS programs should have an ongoing audit of clinical outcomes. Accurate feedback is essential for quality assurance and to ensure process improvement and staff education. Each individual program should follow best practices and compare their outcomes to other centers.

Standardized Order Sets
To standardize the postoperative management of colorectal resection patients, we recommend the creation and implementation of a “postresection” order set. The development of these protocols is based on the evidence-based practices outlined throughout this chapter, and provide a framework for standardizing postoperative care delivered by the surgeon, residents, medical students, nursing staff, and case managers. Serving as a chapter summary and a reliable example, we provided the order sets created and currently used at University of Massachusetts Memorial Medical Center and, for the purpose of this chapter, highlighted those areas that are evidence-based and made comments as appropriate. We tried to identify those that are institutional- or surgeon-based practices where no supportive evidence exists at this point in time ( Table 4-6 ).

TABLE 4-6 University of Massachusetts Memorial Medical Center Standardized Postoperative Order Sets, Including Comments and Current Evidence-Based Recommendations

The operative approaches and postoperative management of patients with colorectal diseases continue to evolve with time. An understanding of normal physiology and response to surgery allows the practitioner to tailor treatment and utilize clinical pathways that facilitate recovery. Advances in the elucidation of hormonal and immune system responses, along with the overall GI recovery process, allow surgeons to more effectively and efficiently manage postoperative fluid status, diet advancement, and multimodal pain control. Evidence-based guidelines now provide recommendations for the prevention of DVT and postoperative infections. For anorectal surgery, similar advances facilitate recovery while preventing complications. Armed with a more comprehensive understanding of these issues, modern surgeons are poised to optimize patient care throughout the perioperative period.


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