1. Principles and Practice of Surgery for the Colon, Rectum,
and Anus Third Edition New York London Philip H. Gordon M.D.,
F.R.C.S. (C), F.A.C.S., F.A.S.C.R.S., Hon. F.R.S.M., Hon.
F.A.C.G.B.I Professor of Surgery and Oncology, McGill University
Director of Colon and Rectal Surgery Sir Mortimer B. Davis-Jewish
General Hospital and McGill University Montreal, Quebec, Canada
Santhat Nivatvongs M.D., F.A.C.S., F.A.S.C.R.S., Hon. F.R.C.S.T.
(Thailand), Hon. F.R.A.C.S. Consultant Surgeon and Professor of
Surgery Mayo Clinic College of Medicine Rochester, Minnesota,
U.S.A. ILLUSTRATORS Scott Thorn Barrows, C.M.I., F.A.M.I Director
and Clinical Assistant Professor, Biomedical Visualization
University of Illinois at Chicago Medical Center with the
assistance of Carla Gunn, Gregory Blew, David Ehlert, Craig Kiefer,
and Kim Martens
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infringe. Library of Congress CataloginginPublication Data Gordon,
Philip H. Principles and practice of surgery for the colon, rectum,
and anus / by Philip H. Gordon, Santhat Nivatvongs. 3rd ed. p. ;
cm. Includes bibliographical references and index. ISBN13:
9780824729615 (alk. paper) ISBN10: 0824729617 (alk. paper) 1. Colon
(Anatomy)Surgery. 2. RectumSurgery. 3. AnusSurgery. I. Nivatvongs,
Santhat. II. Title. [DNLM: 1. Colonic Diseasessurgery. 2. Anus
Diseasessurgery. 3. Colorectal Neoplasmssurgery. 4. Rectal
Diseasessurgery. WI 520 G664p 2006] RD544.G67 2006 617.5547dc22
2006050379 Visit the Informa Web site at www.informa.com and the
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3. Contributors Peter A. Cataldo & Associate Professor of
Surgery, University of Vermont College of Medicine, Fletcher Allen
Health Care, Burlington, Vermont, U.S.A. Jean MacDonald & E.T.
Nurse Consultant, Sir Mortimer B. DavisJewish General Hospital,
Montreal, Quebec, Canada W. Rudolf Schouten & Department of
Surgery, Division of Colon and Rectal Surgery, University Hospital
Dijkzigt, Rotterdam, The Netherlands Lee E. Smith & Clinical
Professor of Surgery, George Washington University, Director,
Section of Colon and Rectal Surgery, Washington Hospital Center,
Washington, D.C. iii
4. I am once again deeply indebted to my wife Rosalie for her
constant patience and understanding through the burden of this
third edition. Her constant life-long support has made all my
professional accomplishments possible. To my wonderful children
Laurel and Elliot of whom I am extremely proud. My love and
gratitude to all. PHG To my two angels Marisa and Nitara. Thinking
of them makes me smile; talking to them recharges my energy.
SN
5. Preface to the Third Edition In the rst edition of this
textbook our goal was to produce a comprehensive book that would
encompass the gamit of colon and anorectal diseases. It was not
intended to be encyclopedic but to provide information for the busy
sur- geon who needed to extract information as quickly as possible.
With this in mind, the contents were divided into ve major sections
that we have been told were helpful and so we have maintained the
basic format through the second and third editions. In the eight
years that have elapsed since our last edi- tion, the proliferation
of information published in the surgical literature makes it
necessary to update and elabo- rate on these developments.
Highlights in the revision include a new discussion of fascial
attachments of the rec- tum and relationship to the lateral pelvic
wall with specic reference to the application for operations on
rectal carcinoma. Newer pharmacologic effects on the internal
sphincter and new investigative modalities for anorectal physiology
are described. The value and role of virtual colonoscopy is
discussed as is the controversy regarding the need for mechanical
bowel preparation. There is a detailed description of the newest
modality of hemorrhoid therapy, namely the stapler hemorrhoidopexy
and its potential role in the armamentarium of hemorrhoid treat-
ment. An extensive section on pharmacologic therapy for
ssure-in-ano has been added and the efcacy of various agents for
chemical sphincterotomy are described. The value of intra-anal
ultrasound and MRI in the diagnosis of complicated recurrent
stula-in-ano have been high- lighted as has the efcacy of brin
glue. A new section on the technique of the repair of rectourethral
stula has been added. Topical agents for condyloma accuminata and
drugs and their dosage for various sexually trans- mitted diseases
have been updated. An extensive review on the therapy for fecal
incontinence including the articial sphincter, hyperbaric oxygen,
Secca procedure, implanta- tion of silicone biomaterial and
detailed description of sacral neuromodulation has been added. The
chapter on the etiology and management of peri- anal neoplasms and
anal carcinoma has been extensively revised reecting new
information, in particular the discus- sion on anal intraepithelial
neoplsia (AIN). This included the new method of diagnosis and
management of high grade AIN of the perianal skin or Bowens
disease. In the benign neoplasms chapter, the relatively new
interest and better understanding of serrated adenoma has been
added. The hot topic on the management of malignant polyps of the
low rectum has been updated. Information on uncommon benign polyps
has been expanded. New data regarding the incidence, prevalence,
and trends in colorectal carcinoma are included. There is an update
on the genetics of colorectal carcinoma in general and in
particular HNPCC. Extensive discussion of the indi- cations for and
interpretation of genetic testing and the invaluable role of
genetic counseling are described in detail. There is an update on
the propriety of adjuvant therapy with its limitations and
complications and possible ne tuning of indications for adjuvant
therapy. There is updated informa- tion on the treatment of
recurrent metastatic carcinoma providing prognostic indicators for
recurrence following therapy. A section on intra-luminal stenting
for obstruction has been added. There is new information on the
staging of rectal carcinoma. There is revised description of
sphincter saving operations (pouch, coloplasty, coloanal
anastomosis). There is a discussion of total mesorectal excision
with results of the use of this technique. There are updated
results on the treatment of carcinoma of the rectum with a
discussion of the propriety of the use of local excision of rectal
carcinoma. There is expansion on the section on palliative
management of patients with rectal carcinoma and there is a
discussion on the role of preoperative neoadjuvant treatment for
rectal carcinoma. A new section on the management of presacral
bleeding has been included. Screening, surveillance, and fol-
low-up for large bowel carcinoma continue to evolve rapidly with
better understanding. The new algorithm for colorectal carcinoma
screening has been revised. The controversy in the surveillance
after surgery has been laid out as guidelines from different major
societies and institutions. The controversy on ileal pouch-anal
anastomosis (IPAA) as primary treatment of chronic ulcercative
colitis has been claried. A better understanding of the risk of
car- cinoma in the ileal pouch and the retained anal canal is
elucidated. The management of chronic pouchitis now includes
immunosuppressive drugs. The long-term out- come of IPAA is now
better understood. The Crohns disease chapter has been extensively
revised with an elabo- rate discussion on the natural history and
classication of the disease and an extensive discussion of the
medical therapies with their limitations and the consideration of
chemoprevention of colorectal carcinoma in inammatory bowel
disease. The changing paradigm regarding the indi- cations for
elective operation in diverticular disease has been revisited along
with the most recent data on results of the treatment of
diverticulitis. The laparoscopy chapter has been totally revised
and expanded. The indications for laparoscopic colectomy have been
revisited and expanded as newer technology has become available and
increased experience has been gained. The new instrumen- tation of
equipment that is available has been outlined including subjects
such as handports and robotic surgery. Techniques of laparoscopic
colectomy have been added. The results of laparoscopic colectomy,
conversion rates, detailed morbidity, and mortality by disease
process have been updated. Difcult situations such as obesity,
vii
6. inammatory masses, and stulas have been described. Quality
of life and cost issues have been included. A major expansion of
the complications, including incidence and prevention of
complications with laparoscopic colectomy have been described. In
the miscellaneous chapter, an entire new section on colon
interposition has been added. The book is replete with color
illustrations and photo- graphs adjacent to the text material
rather than grouped at the beginning, middle, or end of the book.
New illustrations have been added and others redrawn to conform to
better understanding and improvement in operative technique. Color
has been added to many previous black and white illustrations to
enhance the visual image and better display the anatomic details.
Each chapter is heavily referenced. We hope we have accomplished
our goal of summar- izing the enormous body of knowledge published
in the literature and share our personal experience and prefer-
ences with our readers. We strove for a book that strikes a balance
of being authoritative and detailed without being so inclusive that
somewhat irrelevant material and minutia are included. We sincerely
hope our efforts will provide the practicing surgeon and surgeon in
training, the appropriate information to permit them to provide a
rational and up-to- date course of action to the ultimate benet of
each of their patients. Philip H. Gordon Santhat Nivatvongs viii
& PREFACE TO THE THIRD EDITION
7. Preface from the Second Edition Seven years have elapsed
since the rst edition of this book was published and we have been
amazed at the new devel- opments relevant to diseases affecting the
colon, rectum, and anus that have occurred in that relatively short
span of time. Some of these developments have been an out- growth
of the increased knowledge of the disease process and the
underlying genetic factors that inuence it. Others are a reection
of more sophisticated modalities of investi- gation such as
intrarectal ultrasonographic assessment of rectal carcinoma and
positron emission tomography (PET) scanning for recurrent carcinoma
or improved thera- peutic options such as sphincter-saving
operations and newer procedures for fecal incontinence. Added to
this is the yet undened and still controversial role of laparo-
scopic operations to manage a host of colon and rectal disorders.
This proliferation of knowledge has prompted a major revision of
the last edition of this book. Parts have been entirely rewritten
(perianal and anal canal neoplasms, early detection and follow-up
of large bowel carcinoma, and ischemic colitis), others have been
extensively updated (anal incontinence and adjuvant therapy for
colorectal car- cinoma), whereas still others have been greatly
expanded (ssures and Crohns disease). An entirely new chapter on
laparoscopy has been added in view of the current inter- est in
this technique. The exciting new developments in the genetics of
colorectal carcinoma have received the in-depth coverage they
deserve. In our quest to present a balanced view throughout this
book, this endeavor has become almost encyclopedic. As a result,
this textbook has even grown beyond its origi- nal intimidating
size. Despite the size, we have tried to make this information
readily accessible to our readers while maintaining the authors
personal imprint. There- fore, we have preserved our prerogative to
state our preferences when applicable and to reect our individual
perspectives. The basic organization of the subject matter has also
been maintained to permit ready access to infor- mation which we
have attempted to present in a systematic format. New illustrations
have been added and others have been redrawn to better clarify
procedures or disease processes and to further enhance the learning
process. A comprehensive bibliography also accompanies each
chapter. We hope we have accomplished our goal of summar- izing the
staggering body of current knowledge and sharing our own personal
experience and preferences with our readers. Our ultimate objective
has been to address the needs of practicing surgeons,
gastroenterologists, other physicians, residents in training, and
medical students so that they can develop a rational course of
action for each individual patient. Philip H. Gordon Santhat
Nivatvongs ix
8. Preface from the First Edition The creation of any medical
textbook begins as a labor of love but rapidly takes on a life of
its own. This book was no exception. Our goal was to produce a
comprehensive textbook that would encompass the gamut of colon and
anorectal diseases. Emphasis was placed on the fundamen- tals of
disease, with explanation of etiology and pathogenesis given when
applicable, so that the rationale of the proposed treatment would
be better understood. In addition to the what and why, the reader
will learn when and how to institute therapy. This book is not
simply a revision or extension of our previous book, Essentials of
Anorectal Surgery. Since the concepts, thoughts, and practices of
colon and rectal surgery have changed a great deal during the past
decade, current thinking is presented here. This book was not
intended to be encyclopedic. It was written with the busy
practicing surgeon in mindthe sur- geon who needs to extract
information as quickly and easily as possible. Therefore we have
divided the contents of the book into ve major sections. Since our
aim was to be both practical and didactic, we have included theory
along with detailed descriptions of operative procedures. Part I
covers anatomy and physiology and discusses the general principles
of investigation and preparation of the patient for operation. Part
II focuses on anorectal disor- ders, offering discussions of the
various disease entities. It also includes a chapter that
highlights outpatient proce- dures, which play an increasingly
important role in the management of patients with anorectal
disorders. Part III describes colorectal disorders and their
management. Cer- tain subjects that are combined in a miscellaneous
chapter in other books have been ascribed chapter status here. We
believe that this arrangement offers a great convenience to the
reader. Part IV groups a series of subjects related to problem
solving. For example, we have chosen to present together the
complications of diseases and their manage- ment and the
complications of colorectal operations rather than to repeat these
discussions in several chapters. Part V comprises a group of
miscellaneous entities. A number of this books special features are
worthy of comment. Principles and Practice of Surgery for the
Colon, Rec- tum, and Anus is the rst textbook on colon and rectal
surgery to incorporate the liberal use of color. It contains 956
illustrationsx-rays, photographs, and drawings 300 of which are in
color. We strongly believe that the use of color will enhance the
readers understanding of the material. A prime example is the
chapter on perianal der- matologic disease, which is greatly
strengthened by the addition of color. We realize that the chapters
on malignant neoplasms of the colon and the rectum arc lengthy, but
the importance of the subject matter mandates the amount of
material included. Indeed, certain subsections were inten- tionally
abbreviated but extensively referenced. The chapter on diverticular
disease is also long, but because of the controversial nature of
the management of this dis- ease, the size was deemed necessary to
provide a full account of the problem. One subject that is often
not ade- quately addressed in textbooks is the construction and
care of stomas. In contrast, we believe that this topic is
important enough to command an entire chapter. Constipa- tion,
which is only a symptom, may present such a challenge to the
treating physician that a separate chapter has been devoted to it.
Finally, an innovative chapter on unexpected intraoperative ndings
was included to help meet those demanding situations that test the
skill and ingenuity of the surgeon. In discussions of all
controversial issues, an effort was made to present an even-handed
and fair presentation of the problem but always to provide the
reader with the preference of the author. We hope that the reader,
who might be any surgeon or surgeon-in-training who has an interest
in the treatment of colorectal disease, will nd both the
information in this book and its presentation useful. We trust that
the numer- ous illustrations and the use of color will facilitate
understanding and allow us to achieve our goal. Philip H. Gordon
Santhat Nivatvongs xi
9. Acknowledgments Preparation of a major textbook involves the
cooperation and contributions of many people and we would like to
acknowledge the assistance of several individuals. We are most
grateful for the continued friendships, contributions, and support
of Lee E. Smith, M.D., and W. Rudolph Schouten, M.D., who have
provided the time, expertise, and advice through the third edition
of this text- book. We are most appreciative of their unwavering
help. We are also grateful to Peter A. Cataldo, M.D., and Jean
MacDonald, RN CETN for their contributions. For a book of this
magnitude, an enormous amount of skilled secretarial support was
required. We would like to thank Lianna Mantley of the Sir Mortimer
B. DavisJewish General Hospital, Montreal, Canada and Nancy
Beckmann of the Mayo Clinic, Rochester, Minnesota, for their care
in typing and retyping the manuscript. We wish to thank Silvie
Damico for her secretarial assistance throughout the process and
Carmela Masella for handling ofce duties while the manuscript was
being typed. Thanks to Elliot Gordon for gathering the many journal
references required for researching the various topics and thanks
to Laurel Gordon for her lial words of wisdom. A very special word
of thanks to Rosalie Gordon for her unwavering support and advice,
and from whom precious hours were stolen to permit the writing of
the book. Thanks to Marisa Nivat- vongs and Nitara Layton for their
good nature and love. We continue to be blessed and fortunate to
have the very talented medical illustrator Scott Barrows provide
his expertise to this edition. His enormous skill, coopera- tion,
and ability to convert words into images have greatly enhanced the
book. We would also like to thank Joanne Jay of The Egerton Group
Ltd. for her efforts in suc- cessfully assembling a book of this
magnitude and complexity. xiii
10. Contents Contributors / iii Dedication / v Preface to the
Third Edition / vii Preface from the Second Edition / ix Preface
from the First Edition / xi Acknowledgments / xiii Part I:
Essential Considerations & 1: Surgical Anatomy / 1 Santhat
Nivatvongs and Philip H. Gordon Colon / 2 Rectum / 4 Mesorectum / 7
Histology / 7 Anal Canal / 7 Muscles of the Anorectal Region / 10
Anorectal Spaces / 11 Arterial Supply / 15 Venous Drainage / 20
Lymphatic Drainage / 21 Innervation / 23 References / 27 & 2:
Physiology / 29 W. Rudolf Schouten and Philip H. Gordon Colonic
Physiology / 29 Functions / 29 Microora / 38 Intestinal Gas / 40
Anorectal Physiology / 41 Anal Continence / 41 Defecation / 47
Investigative Techniques / 50 Clinical Application / 58 References
/ 61 & 3: Diagnosis / 65 Santhat Nivatvongs Patient History /
66 Physical Examination / 69 Radiologic Examination / 74 Capsule
Endoscopy / 82 Colonoscopy / 82 Examination of Stool / 93
References / 95 & 4: Preoperative and Postoperative Management
/ 99 W. Rudolf Schouten and Philip H. Gordon General Considerations
/ 99 Colon Operation / 102 Anorectal Operation / 112 References /
114 & 5: Local Anesthesia in Anorectal Surgery / 117 Santhat
Nivatvongs Introduction / 117 Selection of Patients / 117
Applicable Conditions / 117 Actions of Agent / 118 Disposition of
Agent / 118 Choice of Agent / 118 Minimizing Pain in Local
Anesthesia / 119 Adverse Reactions / 119 Treatment of Adverse
Reactions / 120 Prevention of Adverse Reactions / 120 Induction of
Anesthesia / 120 Techniques of Local Anesthesia / 121 References /
123 & 6: Pharmacology of Anorectal Preparations / 125 Philip H.
Gordon Introduction / 125 Classication / 126 Dosage Forms / 128
Product Selection Guidelines / 128 Discussion / 128 References /
129 & 7: Electrosurgery and Laser Surgery: Basic Applications /
131 Santhat Nivatvongs and Lee E. Smith Electrosurgery / 131
Denition / 131 Monopolar and Bipolar Electrodes / 131 Basic
Principles / 132 Snare Polypectomy / 133 Hazards / 134 Laser
Surgery / 136 History / 136 Basic Properties of Lasers / 136
Comparison of Surgical Lasers / 137 Clinical Applications / 138
References / 141 xv
11. Part II: Anorectal Disorders & 8: Hemorrhoids / 143
Santhat Nivatvongs What Are Hemorrhoids? / 144 Prevalence / 144
Etiology and Pathogenesis / 145 Predisposing and Associated Factors
/ 145 Function of Anal Cushions / 145 Nomenclature and Classication
/ 146 Diagnosis / 146 Nonoperative Treatment and Minor Operative
Procedures / 148 Hemorrhoidectomy / 150 Special Situations / 152
Early Postoperative Problems / 157 Stapled Hemorrhoidopexy / 158
References / 164 & 9: Fissure-in-Ano / 167 Philip H. Gordon
Introduction / 167 Clinical Features / 167 Pathology / 167 Etiology
/ 168 Predisposing Factors / 168 Pathogenesis / 168 Symptoms / 169
Diagnosis / 170 Differential Diagnosis / 171 Treatment / 172
References / 187 & 10: Anorectal Abscesses and Fistula-in-Ano /
191 Philip H. Gordon Anatomy / 192 Etiology / 192 Pathogenesis /
192 Avenues of Extension / 193 Diagnosis / 193 Anorectal Abscess /
197 Fistula-in-Ano / 203 Special Considerations / 220 References /
230 & 11: Pilonidal Disease / 235 Santhat Nivatvongs
Introduction / 235 Etiology and Pathogenesis / 235 Surgical
Pathology / 236 Natural History / 236 Predisposing Factors / 236
Clinical Manifestations / 237 Diagnosis / 237 Treatment / 238
Summary / 241 Role of Hair / 243 Recurrent Disease / 243 Unhealed
Wound / 243 Pilonidal Sinus and Carcinoma / 245 References / 246
& 12: Perianal Dermatologic Disease / 247 Lee E. Smith
Introduction / 247 Pruritic Conditions / 247 Idiopathic Pruritus
Ani / 247 Primary Etiologies / 250 Nonpruritic Lesions / 258
Infections / 258 Neoplastic Lesions / 258 Inammatory Bowel Disease
/ 259 References / 259 & 13: Condyloma Acuminatum / 261 Philip
H. Gordon Introduction / 261 Clinical Features / 261 Pathology /
262 Symptoms / 263 Diagnosis / 263 Treatment / 263 Recurrence / 268
Posttreatment Follow-Up / 269 Resumption of Sexual Intercourse /
269 Condylomata Acuminata in Children / 269 Verrucous Carcinoma /
269 Condyloma Acuminatum and Squamous Cell Carcinoma / 270
References / 271 & 14: Sexually Transmitted Diseases / 275 Lee
E. Smith Gastrointestinal Sexually Transmitted Diseases / 275
Epidemiology / 275 Diagnosis / 276 Bacterial Infection / 277
Spirochete Infection / 279 Viral Infection / 280 Parasitic
Infection / 280 Acquired Immunodeciency Syndrome / 281 Short
History of AIDS / 281 Pathogenesis / 282 Clinical Presentation /
282 Seroconversions / 283 Gastrointestinal Manifestations / 283
Opportunistic Infection / 284 Malignancies / 286 Colorectal Surgery
in AIDS Patients / 286 AIDS and the Health Care Worker / 288
References / 288 xvi & CONTENTS
12. & 15: Fecal Incontinence / 293 Philip H. Gordon and W.
Rudolf Schouten Introduction / 293 Etiology / 295 Diagnosis / 300
Treatment / 305 References / 326 & 16: Rectovaginal Fistula /
333 Philip H. Gordon Introduction / 333 Clinical Evaluation / 333
Classication / 334 Etiology / 334 Operative Repair / 336
Rectourethral Fistula / 347 References / 351 & 17: Retrorectal
Tumors / 353 Philip H. Gordon Anatomy / 353 Classication / 353
Incidence / 354 Pathology / 354 Clinical Presentation / 360
Diagnostic Measures / 361 Operative Approaches / 363 Adjuvant
Therapy / 366 Results / 366 References / 367 & 18: Perianal and
Anal Canal Neoplasms / 369 Santhat Nivatvongs Introduction / 369
Anatomic Landmarks / 369 Incidence / 370 Etiology and Pathogenesis
/ 370 Staging / 371 Screening for Anal Carcinoma Precursors / 371
Human Papilloma Virus Type 16 Vaccine / 371 Perianal Neoplasms
(Anal Margin) / 373 Neoplasms of the Anal Canal / 379 References /
388 & 19: Transanal Techniques / 391 Santhat Nivatvongs
Introduction / 391 Rectal Biopsy / 391 Electrocoagulation of Rectal
Polyps / 392 Snare Polypectomy / 392 Transanal Excision of Rectal
Adenoma / 392 Transanal Excision for Carcinoma of the Low Rectum /
396 Posterior Approach to the Rectum / 396 Transanal Endoscopic
Microsurgery / 399 Electrocoagulation of Carcinoma of the Rectum /
401 References / 402 & 20: Ambulatory Procedures / 405 Peter A.
Cataldo and Philip H. Gordon Introduction / 405 Preoperative
Assessment / 407 Operative Management / 407 Procedures / 408
Postoperative Care / 411 Complications / 412 Benets / 412
References / 413 Part III: Colorectal Disorders & 21: Rectal
Procidentia / 415 Philip H. Gordon Introduction / 415 Etiology /
415 Classication / 416 Predisposing Factors / 417 Pathologic
Anatomy / 417 Physiologic Dysfunction / 417 Clinical Features / 418
Investigation / 420 Operative Repair / 421 Subsequent Management /
439 Complications / 440 Recurrent Rectal Prolapse / 441 Prolapse in
Children / 442 Hidden Prolapse (Internal Procidentia) / 442 Summary
/ 443 Solitary Ulcer Syndrome of the Rectum / 444 References / 448
& 22: Benign Neoplasms of the Colon and Rectum / 451 Santhat
Nivatvongs Polyps of Colon and Rectum / 452 Familial Adenomatous
Polyposis / 466 Hemangiomas of Large Bowel / 480 Leiomyomas of
Large Bowel / 481 Lipomas of Large Bowel / 482 References / 483
& 23: Malignant Neoplasms of the Colon / 489 Philip H. Gordon
Classication / 490 Adenocarcinoma / 490 Incidence, Prevalence, and
Trends / 490 Epidemiology / 491 Age / 491 Sex / 491 Family History
/ 491 Site / 492 Geographic Distribution / 492 Race and Religion /
492 Occupation / 492 Etiology and Pathogenesis / 493 Polyp-Cancer
Sequence / 493 Inammatory Bowel Disease / 493 Genetics / 493
Dietary Factors / 510 CONTENTS & xvii
13. Irradiation / 515 Ureteric Implantation / 515
Cholecystectomy / 516 Diverticular Disease / 516 Activity and
Exercise / 516 Other Factors / 517 Juvenile vs. Adult Carcinoma /
518 Prospects for Prevention / 519 Pathology / 520 Macroscopic
Appearance / 520 Microscopic Appearance / 521 Depressed Carcinoma /
523 Sentinel Lymph Node Mapping / 525 Modes of Spread / 526 Site of
Spread / 527 Staging / 527 Biology of Growth / 530 Clinical
Features / 532 Symptoms / 532 General and Abdominal Examinations /
533 Digital Rectal Examination / 533 Extraintestinal Manifestations
/ 533 Synchronous Carcinomas / 533 Associated Polyps / 533 Other
Associated Malignancies / 534 Complications / 534 Obstruction / 534
Perforation / 535 Bleeding / 535 Unusual Infections Associated with
Colorectal Carcinoma / 535 Diagnosis / 535 Investigations / 536
Occult Blood Testing / 536 Endoscopy / 536 Radiology / 536
Radioimmunodetection / 539 Cytology / 540 Blood Markers / 540
Treatment / 542 Curative Resection / 542 Adjuvant Therapy / 555
Complicated Carcinomas / 561 Perforation / 566 Bleeding / 566
Obstructive Colitis / 566 Invasion of Adjacent Viscera / 567
Urinary Tract Involvement by Colorectal Carcinoma / 569 Primary
Involvement of the Urinary Tract / 569 Bladder Involvement / 570
Ureteric Involvement / 570 Fistula / 570 Hydronephrosis / 571
Radiotherapy / 571 Unexpected Intraoperative Involvement / 571
Recurrent Colorectal Carcinoma / 571 Abnormal Renal Function / 571
Palliation / 571 Unresectable Carcinoma / 571 Palliative Resection
/ 571 Synchronous Carcinomas / 572 Synchronous Polyps and Carcinoma
/ 572 Metachronous Carcinoma / 572 Treatment of Metastatic Disease
/ 573 Carcinoma in Young Patients / 585 Postoperative Complications
/ 585 Results / 586 Prognostic Discriminants / 590 Clinical
Features / 590 Pathologic Features / 598 Biochemical and Special
Investigations / 602 Recurrent Disease / 604 Follow-Up / 604
Incidence / 604 Contributing Factors / 604 Patterns / 605 Clinical
Features / 606 Investigations / 606 Role of Carcinoembryonic
Antigen / 607 Treatment / 608 Results of Reoperation / 613
Intestinal Obstruction Due to Recurrent Carcinoma / 613 Colorectal
Carcinoma Complicating Pregnancy / 614 Ovarian Carcinoma Involving
the Colon / 615 Malakoplakia and Colorectal Carcinoma / 615 Other
Malignant Lesions / 615 Carcinoid / 615 Incidence / 616 Clinical
Features / 616 Pathology / 616 Imaging Procedures / 617 Chemical
Activity / 617 Treatment / 618 Results / 618 Lymphoma / 618
Incidence / 618 Pathology / 618 Clinical Features / 619 Treatment /
620 Results / 620 Sarcoma / 620 Squamous Cell Carcinoma / 621
Adenosquamous Carcinoma / 622 Plasmacytoma / 622 Melanoma / 622
Leukemic Inltration / 623 Neuroendocrine Lesions of the Colorectum
/ 623 Medullary Carcinoma of the Colon / 623 Carcinosarcoma / 624
Schwannoma / 624 Angiosarcoma / 624 Choriocarcinoma / 624
Metastases from Other Sources / 625 References / 625 & 24:
Malignant Neoplasms of the Rectum / 645 Philip H. Gordon
Adenocarcinoma / 646 Mechanisms of Spread of Rectal Carcinoma / 646
Direct Extension / 646 Transperitoneal Spread / 646 Implantation /
646 Lymphatic Spread / 646 Venous Spread / 646 Clinical Features /
647 Symptoms / 647 General and Abdominal Examination / 647
Investigations / 647 Endoscopy / 647 Routine Laboratory Blood Work
/ 647 Radiology / 647 Preoperative Preparation / 651 Radical
Extirpative Operations / 652 Assessment of Resectability / 652
Selection of Appropriate Operation / 652 Operative Procedures / 654
Postoperative Care / 674 Results / 674 xviii & CONTENTS
14. Local Forms of Therapy / 683 Rationale / 683 Procedures /
683 Special Considerations / 691 Distal Margins / 691
Circumferential Margins / 692 Total Mesorectal Excision / 692
Radical Lymphadenectomy / 696 Concomitant Pelvic Organ Excision /
698 Palliative Therapy for Advanced Rectal Carcinoma / 699
Hartmanns Procedure / 702 Unresectable Carcinoma of the Rectum /
702 High Ligation of Inferior Mesenteric Artery / 703 Marking the
Rectum / 703 Adjuvant Therapy for Carcinoma of the Rectum / 704
Radiotherapy / 704 Chemotherapy / 712 Combination Chemoradiotherapy
/ 712 Immunotherapy / 717 Summary / 718 Postoperative Complications
/ 718 Recurrent Disease / 718 Follow-up / 718 Incidence / 718
Factors Contributing to Recurrence / 719 Patterns of Recurrence /
719 Clinical Features / 720 Investigations / 720 Treatment of
Recurrent Disease / 721 Results of Reoperation / 728 Other
Malignant Lesions of the Rectum / 728 Carcinoid / 728 Clinical
Presentation / 729 Investigation / 729 Pathology / 729 Treatment /
729 Results / 729 Lymphoma / 730 Clinical Presentation / 730
Treatment and Results / 730 Sarcoma / 730 Gastrointestinal Stromal
Tumor (GIST) / 731 Secondary Carcinoma / 732 Miscellaneous
Neoplasms / 732 References / 732 & 25: Large Bowel Carcinoma:
Screening, Surveillance, and Follow-Up / 743 Santhat Nivatvongs
Detection of Early Colorectal Carcinoma / 743 Early Diagnosis of
Colorectal Carcinoma / 744 What Is Screening? / 744 Who Should Be
Screened? / 744 Screening People at Average Risk for Colorectal
Carcinoma / 745 Screening People at Increased Risk for Colorectal
Carcinoma / 747 New Screening Tests / 748 When to Stop Screening /
748 Surveillance / 749 Follow-Up after Curative Resection / 750
Other Primary Malignancies / 751 Summary / 751 References / 752
& 26: Ulcerative Colitis / 755 Santhat Nivatvongs Introduction
/ 756 Epidemiology and Etiology / 756 Clinical Course / 757
Clinical Manifestations / 757 Diagnosis / 757 Assessment of
Severity / 758 Pathologic Features / 759 Gross Appearance / 759
Microscopy / 760 Differential Diagnosis / 761 Crohns Disease / 761
Clostridium Difcile Colitis / 761 Campylobacter Gastroenteritis /
763 Salmonella Enterocolitis / 763 Escherichia Coli 0157:H7 / 764
Amebiasis / 765 Collagenous Colitis / 765 Risk of Carcinoma / 767
Surveillance / 767 Problems with Colonoscopy and Biopsy / 768 A
Practical Guide / 768 Extracolonic Manifestations / 769 Hepatic
Dysfunction / 769 Primary Sclerosing Cholangitis and Bile Duct
Carcinoma / 769 Arthritis / 771 Ankylosing Spondylitis and
Sacroiliitis / 771 Erythema Nodosum / 771 Pyoderma Gangrenosum /
771 Ulcers of Mouth / 772 Eye Diseases / 772 Ulcerative Colitis and
Pregnancy / 772 Drugs for Ulcerative Colitis / 772 Sulfasalazine
(Azuldine) / 772 Aminosalicylates / 773 Corticosteroids / 773
Budesonide / 773 Antibiotics / 773 Immunosuppressive Drugs / 773
Medical Management / 774 Proctitis / 774 Proctosigmoiditis / 774
Left-Sided Colitis and Pancolitis / 775 Anemia in Inammatory Bowel
Disease / 775 Severe or Fulminant Colitis / 775 Steroid-Refractory
Ulcerative Colitis / 776 Steroid-Dependent Ulcerative Colitis / 777
Natural History of Treated Ulcerative Colitis / 777 Course of
Severe Ulcerative Colitis / 777 Course of Active and Chronic
Ulcerative Colitis / 778 Indications for Operation / 778
Intractability / 778 Fulminant Colitis / 778 Toxic Megacolon / 778
Massive Bleeding / 779 Prophylaxis for Carcinoma / 779 Carcinoma /
779 Cutaneous and Systemic Complications / 780 Operative Options /
780 Total Proctocolectomy and Ileostomy / 780 Colectomy with
Ileostomy and Hartmanns Procedure / 780 Colectomy with Ileorectal
Anastomosis / 780 Total Proctocolectomy with Continent Ileostomy
(Kocks Pouch) / 781 Total Proctocolectomy with Ileal PouchAnal
Anastomosis / 784 Selection of Patients / 786 Special Situations /
795 Indeterminate Colitis / 795 Inadvertent Crohns Disease / 796
CONTENTS & xix
15. Ulcerative Colitis with Carcinoma / 797 Adenocarcinoma in
Ileal PouchAnal Anastomosis / 797 Pregnancy / 799 Older Patients /
799 Complications / 800 Small Bowel Obstruction / 800 Pelvic
Abscess / 800 Leakage of Pouch and PouchAnal Anastomosis / 801
Vaginal Fistula / 801 Anal Stricture / 802 Difcult Evacuation / 803
Portal Vein Thrombosis / 804 Pouchitis / 804 Reoperation for
Pouch-Related Complications / 806 Sexual Dysfunction / 807 Complete
Failure of Ileal PouchAnal Anastomosis / 808 Functional Results /
808 Stool Frequency / 808 Fecal Incontinence / 809 Metabolic
Function / 810 Patient Satisfaction with Ileal PouchAnal
Anastomosis / 811 References / 811 & 27: Crohns Disease / 819
Santhat Nivatvongs and Philip H. Gordon Introduction / 820
Epidemiology / 820 Etiology and Pathogenesis / 821 Pathology / 825
Clinical Manifestations / 826 Diagnosis / 826 Endoscopy / 827
Contrast Studies / 827 Nuclear Scans / 828 ASCA Test / 828
Ultrasonography / 828 Computed Tomography / 829 Magnetic Resonance
Imaging / 829 Capsule Endoscopy / 829 Virtual Colonoscopy / 829 New
Diagnostic Criteria / 830 Differential Diagnosis / 830 Natural
History / 830 Classication / 833 Medical Management / 834
Sulfasalazine and 5-aminosalicylic Acid / 835 Antibiotics / 835
Corticosteroids / 835 Immunosuppressive Agents / 836 Biologic
Modiers / 838 Analgesics / 841 Nutrition / 842 Smoking Cessation /
842 Probiotics / 843 Summary / 843 Indications for Operation / 844
Intractability to Medical Treatment / 845 Bowel Obstruction / 845
Intra-abdominal Abscess / 845 Internal Fistula / 846 Colocutaneous
and Enterocutaneous Fistula / 847 Fulminant Colitis / 847 Toxic
Megacolon / 848 Free Perforation / 848 Massive Bleeding / 849
Carcinoma Prevention / 849 Carcinoma / 850 Extracolonic
Manifestations / 850 Growth Retardation / 850 Overview / 850
Interventional Options and Their Results / 850 Ileocecal Resection
/ 850 Total Proctocolectomy and Ileostomy / 851 Subtotal Colectomy
with Closure of Rectal or Sigmoid Stump or Mucous Fistula and
Ileostomy / 851 Fate of Rectal Stump / 852 Colectomy with
Ileorectal Anastomosis / 852 Ileostomy / 853 Segmental Colon
Resection / 853 Operations for Intestinal Fistula / 854 Bypass
Operation / 855 Small Bowel Resection / 855 Strictureplasty / 856
Percutaneous Drainage of Intra-Abdominal Abscess / 860 Stricture
Dilatation / 861 Likelihood of Stoma Necessity / 862 Fate of Ileal
Pouch-Anal Anastomosis in Unsuspected Crohns Disease / 862 How Much
Bowel to Resect / 864 Overview of Results / 864 Challenging
Anatomic Locations of Crohns Disease / 867 Oropharynx / 867
Esophagus / 867 Gastroduodenum / 868 Diffuse Jejunoileitis / 870
Appendix / 871 Perianal and Anal Canal Crohns Disease / 871 Special
Considerations / 880 Extracolonic Manifestations / 880
Hepatobiliary Manifestations / 881 Risk of Carcinoma / 882
Chemoprevention of Colorectal Carcinoma / 887 Crohns Disease and
Pregnancy / 888 Recurrence / 890 Factors Inuencing Recurrence / 890
Maintaining Remission in Crohns Disease / 893 Summary / 896
References / 899 & 28: Diverticular Disease of the Colon / 909
Philip H. Gordon Introduction / 910 Pathologic Anatomy / 910
Incidence / 910 Etiology / 912 Pathogenesis / 913 Pathology / 916
Patterns of Disease / 917 Natural History / 918 Clinical
Manifestations / 920 Diagnosis / 920 Treatment / 922 Complications
/ 928 Results and Prognosis / 957 Right-Sided Diverticula / 958
Giant Colonic Diverticulum / 962 Coexisting Disorders / 962 Special
Problems / 964 References / 965 & 29: Volvulus of the Colon /
971 Santhat Nivatvongs Introduction / 971 Sigmoid Volvulus / 971 xx
& CONTENTS
16. Ileosigmoid Knotting / 979 Sigmoid Volvulus in Pregnancy /
981 Cecal Volvulus / 981 Volvulus of Transverse Colon / 983 Splenic
Flexure Volvulus / 984 References / 984 & 30: Mesenteric
Vascular Diseases / 987 Philip H. Gordon Vascular Anatomy / 987
Pathophysiology of Intestinal Ischemia / 988 Diagnostic Studies /
990 Clinical Syndromes / 991 Superior Mesenteric Artery Embolism /
991 Superior Mesenteric Artery Thrombosis / 993 Nonocclusive
Mesenteric Ischemia and Infarction / 994 Mesenteric Venous
Thrombosis / 995 Chronic Mesenteric Vascular Disease / 996 Ischemic
Colitis / 999 Ischemic Colitis and Aortoiliac Surgery / 1007 Total
Colonic Ischemia / 1010 Ischemic Proctitis / 1010 References / 1011
& 31: Radiation Injuries to the Small and Large Intestine /
1015 Santhat Nivatvongs Introduction / 1015 Incidence and Clinical
Manifestations / 1015 Mechanisms of Radiation Injury / 1016
Pathology / 1016 Pathogenesis / 1017 Predisposing Factors / 1018
Small Intestine Injuries / 1018 Colon and Rectal Injuries / 1020
Radiation Proctitis / 1024 Increased Risk of Rectal Carcinoma after
Prostate Radiation / 1025 Prevention / 1026 References / 1028 &
32: Intestinal Stomas / 1031 Philip H. Gordon, Jean MacDonald, and
Peter A. Cataldo Introduction / 1032 Ileostomy / 1032 Colostomy /
1039 Outcomes of Stomal Construction and Closure / 1060
Enterostomal Care and Rehabilitation / 1061 References / 1077 &
33: Constipation / 1081 W. Rudolf Schouten and Philip H. Gordon
Introduction / 1082 Denition / 1082 Etiology / 1083 Investigation /
1084 Why Treat Constipation? / 1094 Treatment / 1095 Special
Considerations / 1114 References / 1117 Part IV: Problem-Oriented
Approach to Colorectal Disease & 34: Traumatic Injuries / 1125
Lee E. Smith Etiology / 1125 Penetrating Trauma / 1125 Blunt Trauma
/ 1126 Iatrogenic Injury / 1126 Ingested Foreign Bodies / 1130
Foreign Bodies and Sexual Trauma / 1130 Sexual Assault / 1131 Child
Abuse / 1131 Unusual Perforations / 1132 Management / 1132
Diagnosis of Trauma (Secondary Survey Phase) / 1132 Laparoscopy /
1134 Surgical Treatment (Denitive Care Phase) / 1134 References /
1143 & 35: Complications of Colonic Disease and Their
Management / 1147 Santhat Nivatvongs Acute Colonic Obstruction /
1148 Free Perforation / 1150 Neutropenic Enterocolitis / 1151
Massive Bleeding / 1152 Fistula / 1158 References / 1162 & 36:
Complications of Anorectal and Colorectal Operations / 1165 Santhat
Nivatvongs Introduction / 1166 Early Complications of Anorectal
Operations / 1166 Delayed Complications of Anorectal Operations /
1167 Complications of Colorectal Operations / 1169 References /
1187 & 37: Unexpected Intraoperative Findings / 1191 Philip H.
Gordon, Santhat Nivatvongs, and Lee E. Smith Introduction / 1191
Case 1: Carcinoma of Rectum and Unexpected Synchronous Carcinoma of
Hepatic Flexure / 1191 Case 2: Carcinoma of Right Colon and
Unexpected Major Single Hepatic Metastasis / 1192 Case 3: Sigmoid
Mass that Proves to Be Endometrioma Instead of Carcinoma / 1192
Case 4: Exploration for Appendicitis that Proves to Be Carcinoma of
Cecum / 1193 Case 5: Pelvic Laparotomy for Gynecologic Mass that
Proves to Be Carcinoma of Sigmoid / 1193 CONTENTS & xxi
17. Case 6: Exploration for Acute Appendicitis that Proves to
Be Sigmoid Phlegmon / 1194 Case 7: Carcinoma of Rectum with
Incidental Cholelithiasis / 1194 Case 8: Carcinoma of Rectum with
Invasion of Urinary Bladder / 1195 Case 9: Concomitant Carcinoma of
Rectum and Abdominal Aortic Aneurysm / 1196 Case 10: Propriety of
Incidental Appendectomy / 1197 Case 11: Propriety of Incidental
Meckels Diverticulectomy / 1198 Case 12: Rectal Prolapse and
Unexpected Ovarian Mass / 1199 Case 13: Vaginal Hysterectomy and
Intraoperative Perforation of Rectum / 1199 Case 14: Exploration
for Appendicitis with Unexpected Pseudomyxoma Peritonei / 1200
Conclusion / 1200 References / 1200 Part V: Minimally Invasive
Surgery & 38: Laparoscopic Colon and Rectal Surgery / 1203 Lee
E. Smith and Philip H. Gordon Background and Rationale / 1204
Indications / 1205 Equipment and Instrumentation / 1207 Operative
Procedure / 1211 Specic Colorectal Procedures / 1214 Robotics /
1227 Postoperative Care / 1228 Results / 1228 Laparoscopic
Complications and Their Prevention / 1257 References / 1261 Part
VI: Et Cetera & 39: Miscellaneous Entities / 1267 Philip H.
Gordon Coccygodynia / 1268 Endometriosis / 1271 Proctalgia Fugax
and Levator Syndrome / 1274 Oleogranuloma / 1276 Melanosis Coli /
1277 Colitis Cystica Profunda / 1278 Descending Perineum Syndrome /
1279 Pneumatosis Coli / 1281 Hidradenitis Suppurativa / 1284 Anal
Leukoplakia / 1288 Diversion Colitis / 1288 Segmental or
Diverticula-Associated Colitis / 1289 Aortoenteric Fistula / 1290
Colon Interposition / 1291 References / 1295 Index / 1299 xxii
& CONTENTS
19. Although seemingly a single organ, the colon is embryo-
logically divisible into two parts. The transverse colon and
portions proximal to it are derived from the midgut and are
supplied by the superior mesenteric artery, while the distal half
of the colon is derived from the hindgut and receives blood from
the inferior mesenteric artery. The large bowel begins in the right
lower quadrant of the abdomen as a blind pouch known as the cecum.
The ileum empties into the medial and posterior aspect of the
intestine, a point known as the ileocecal junction. The colon
proceeds upward and in its course is designated according to
location as: ascending colon, hepatic exure, transverse colon,
splenic exure, descending colon, sigmoid colon, rec- tum, and anal
canal. The colon is approximately 150 cm long, and its diameter
gradually diminishes from the cecum to the rectosigmoid junction,
where it widens as the rectal ampulla, only to narrow again as the
anal canal. & COLON & GENERAL CONFIGURATION The colon
differs from the small bowel in that it is character- ized by a
saccular or haustral appearance, it contains three taenia bands,
and it has appendices epiploicae, a series of fatty appendages
located on the antimesenteric surface of the colon. The taenia
bands are longitudinal muscle run- ning along the colon from the
base of the appendix. They merge in the distal sigmoid colon, where
the longitudinal bers continue through the entire length of the
rectum. A study by Fraser et al. (1) has shown that the
longitudinal muscle forms a complete coat around the colon but is
much thicker at the taeniae. The three taenia bands are named
according to their relation to the transverse colon: taenia
mesocolica, which is attached to the mesocolon; taenia omen- talis,
which is attached to the greater omentum; and taenia libera, which
has no attachment. These bands are about one sixth shorter than the
intestine and are believed to be responsible for the sacculations
(2). The transition from the sigmoid colon to the rectum is a
gradual one. It is characterized by the taeniae coli spread- ing
out from three distinct bands to a uniformly distributed layer of
longitudinal smooth muscle that is thicker on the front and back
than on each side. & COURSE AND RELATIONS The general
topography of the colon varies from person to person, and such
differences should be taken into account while reading the
following discussion (Fig. 1). The vermiform appendix projects from
the lowermost part of the cecum. From the ileocecal junction the
colon ascends on the right in front of the quadratus lumborum and
transversus abdominis muscles to a level overlying the lower pole
of the right kidney, a distance of about 20 cm. It is invested by
peritoneum on its anterior, lateral, and medial surfaces. Superior
to the colon is the undersur- face of the right lobe of the liver,
lateral to the gallbladder, and here the colon angulates acutely
medially, downward, and forward, forming the hepatic exure.
Occasionally there is a lmy web of adhesions extending from the
right abdominal wall to the anterior taenia of the ascending colon,
and this has been referred to as Jacksons membrane. FIGURE 1 &
General topography of the large bowel. (A) Colon. (B) Peritoneum
and adjacent structures. 2 & PART I: ESSENTIAL
CONSIDERATIONS
20. The transverse colon is the longest (4050 cm) segment of
colon, extending from the hepatic to the splenic exure. It is
usually mobile and may descend to the level of the iliac crests or
even dip into the pelvis. The transverse colon is enveloped between
layers of the transverse mesocolon, the root of which overlies the
right kidney, the second por- tion of the duodenum, the pancreas,
and the left kidney. It contains the middle colic artery, branches
of the right and left colic arteries, and accompanying veins,
lymphatic structures, and autonomic nerve plexuses. This posterior
relationship is of paramount importance because these structures
are subject to injury during a right hemi-colect- omy if proper
care is not exercised. In the left upper quadrant of the abdomen,
the colon is attached to the undersurface of the diaphragm at the
level of the 10th and 11th ribs by the phrenocolic ligament. The
distal trans- verse colon lies in front of the proximal descending
colon. The stomach is immediately above and the spleen is to the
left. The greater omentum descends from the greater curva- ture of
the stomach in front of the transverse colon and ascends to the
upper surface of the transverse colon. The splenic exure describes
an acute angle, is high in the left upper quadrant, and therefore
is less accessible to operative approach. It lies anterior to the
midportion of the left kidney. The descending colon passes along
the posterior abdominal wall over the lateral border of the left
kidney, turns somewhat medially, and descends in the groove between
the psoas and the quadratus lumborum muscles to its junction with
the sigmoid at the level of the pelvic brim and the transversus
abdominis muscle (3). Its length averages 30 cm. The anterior,
medial, and lateral portions of its circumference are covered by
peritoneum. The distal por- tion of the descending colon is usually
attached by adhesions to the posterior abdominal wall, and these
adhesions require division during mobilization of this portion of
the colon. The sigmoid colon extends from the pelvic brim to the
sacral promontory, where it continues as the rectum. Its length
varies dramatically from 15 to 50 cm, and it may follow an
extremely tortuous and variable course. It often loops to the left
but may follow a straight oblique course, loop to the right, or
ascend high into the abdomen. It has a generous mesentery and is
extremely mobile. The serosal surface has numerous appendices
epiploicae. The base of the mesocolon extends from the iliac fossa,
along the pelvic brim, and across the sacroiliac joint to the
second or third sacral segment; in so doing, it forms an inverted
V. Con- tained within the mesosigmoid are the sigmoidal and
superior rectal arteries and accompanying veins, lymphat- ics, and
autonomic nerve plexuses. At the base of the mesosigmoid is a
recess, the intersigmoid fossa, which serves as a valuable guide to
the left ureter, lying just deep to it. The upper limb runs
medially and upward, crossing the left ureter and iliac vessels;
this is an extremely impor- tant relationship during resection of
this part of the colon. The lower limb extends in front of the
sacrum and also may be alongside loops of small bowel, the urinary
bladder, and the uterus and its adnexa. Saunders et al. (4)
conducted a novel study in which they investigated possible
differences in colonic anatomy and mesenteric attachmentsbetween
Western(Caucasian)and Ori- ental patients. Measurements of colonic
length and mesenteric attachments were taken according to a set
protocol from 115 Western and 114 Oriental patients at laparotomy.
Sig- moid adhesions were found more frequently in Western patients
(17%) compared to Oriental patients (8%) (p 0.047). A descending
mesocolon of !10 cm occurred in 10 (8%) Western patients but only
one (0.9%) Oriental patient (p 0.01). The splenic exure was more
frequently mobile in Western (20%) compared to Oriental patients
(9%) (p 0.016). In 29% of Western patients, the midtrans- verse
colon reached the symphysis pubis, or lower when pulled downward,
in contrast to that nding in 10% of Oriental patients (p <
0.001). There was no signicant dif- ference in total colonic length
when Western patients (median, 114 cm; range, 68159 cm) were
compared with Oriental patients (median, 111 cm; range, 78161 cm).
Western patients have a higher incidence of sigmoid colon adhesions
and increased colonic mobility when compared with Orientals. These
ndings support the observation that colonoscopy is a more difcult
procedure to perform on Western patients. & PERITONEAL
COVERINGS The antimesenteric border of the distal ileum may be
attached to the parietal peritoneum by a membrane (Lanes membrane)
(5). The cecum usually is entirely enveloped by peritoneum. The
ascending colon is attached to the poste- rior body wall and is
devoid of peritoneum in its posterior surface; thus, it does not
have a mesentery. The transverse colon is invested with peritoneum.
Its posterosuperior sur- face, along the taenia band, is attached
by the transverse mesocolon to the lower border of the pancreas.
The poste- rior and inferior layers of the greater omentum are
fused on the anterosuperior aspect of the transverse colon. To
mobi- lize the greater omentum or to enter the lesser sac, the
fusion of the omentum to the transverse colon must be dis- sected.
Because the omental bursa becomes obliterated caudal to the
transverse colon and toward the right side, the dissection should
be started on the left side of the trans- verse colon. Topor et al.
(6) studied 45 cadavers to elucidate surgical aspects of omental
mobilization, lengthening, and transposition into the pelvic
cavity. They identied that the most important anatomic variables
for omental transpo- sition were three variants of arterial blood
supply: (i) In 56% of patients, there is one right, one (or two)
middle, and one left omental artery. (ii) In 26% of patients, the
mid- dle omental artery is absent. (iii) In the remaining 18% of
patients, the gastroepiploic artery is continued as a left omental
artery but with various smaller connections to the right or middle
omental artery. The rst stage of omen- tal lengthening is
detachment of the omentum from the transverse colon mesentery. The
second stage is the actual lengthening of the omentum. The third
stage is placement of the omental ap into the pelvis. The left
colonic exure is attached to the diaphragm by the phrenocolic
ligament, which also forms a shelf for supporting the spleen. The
des- cending colon is devoid of peritoneum posteriorly, where it is
in contact with the posterior abdominal wall and thus has no
mesentery. The sigmoid colon begins at about the level of the
pelvic brim and is completely covered with peritoneum. The
posterior surface is attached by a fan-shaped mesen- tery. The
lateral surface of the sigmoid mesentery is fused to the parietal
peritoneum of the lateral abdominal wall CHAPTER 1: SURGICAL
ANATOMY & 3
21. and is generally known as the white line of Toldt. Mobi-
lization of the sigmoid colon requires cutting or incising the
lateral peritoneal reection. The sigmoid colon varies greatly in
length and conguration. & ILEOCECAL VALVE The superior and
inferior ileocecal ligaments are brous tis- sue that helps maintain
the angulation between the ileum and the cecum. Kumar and Phillips
(7) found these struc- tures to be important in the maintenance of
competence against reux at the ileocecal junction. In an autopsy
evaluation, the ascending colon was lled with saline solution by
retrograde ow, and in 12 of 14 cases the ileo- cecal junctions were
competent to pressures up to 80 mmHg. Removal of mucosa at the
ileocecal junction or a strip of circular muscle did not impair
competence to pres- sures above 40 mmHg, but division of the
superior and inferior ileocecal ligaments rendered the junction
incompe- tent. Operative reconstruction of the ileocecal angle
restored competence. It therefore appears that the angulation
between the ileum and the cecum determines continence. & RECTUM
Although anatomists traditionally assign the origin of the rectum
to the level of the third sacral vertebra, surgeons generally
consider the rectum to begin at the level of the sacral promontory.
It descends along the curvature of the sacrum and coccyx and ends
by passing through the levator ani muscles, at which level it
abruptly turns down- ward and backward to become the anal canal.
The rectum differs from the colon in that the outer layer is
entirely longitudinal muscle, characterized by the merging of the
three taenia bands. It measures 1215 cm in length and lacks a
mesentery, sacculations, and appendices epiploicae. The rectum
describes three lateral curves: the upper and lower curves are
convex to the right, and the middle is convex to the left. On their
inner aspect these infoldings into the lumen are known as the
valves of Houston (8,9). About 46% of normal persons have three
valves, 33% have two valves, 10% have four valves, 2% have none,
and the rest have from ve to seven valves (9). The clinical signi-
cance of the valves of Houston is that they must be negotiated
during successful proctosigmoidoscopic exami- nation and, more
importantly, that they are an excellent location for a rectal
biopsy, because the inward protrusion makes an easy target. They do
not contain all the layers of the bowel wall, and therefore biopsy
in this location car- ries a minimal risk of perforation. The
middle fold is the internal landmark corresponding to the anterior
peritoneal reection. Consequently, extra caution must be exercised
in removing polyps above this level. Because of its curves, the
rectum can gain 5 cm in length when it is straightened (as in
performing a low anterior resection); hence, a lesion that
initially appears at 7 cm from the anal verge is often found 12 cm
from that site after complete mobilization. In its course the
rectum is related posteriorly to the sacrum, coccyx, levator ani
muscles, coccygeal muscles, median sacral vessels, and roots of the
sacral nerve plexus. Anteriorly in the male, the extraperitoneal
rectum is related to the prostate, seminal vesicles, vasa
deferentia, ureters, and urinary bladder; the intraperitoneal
rectum may come in contact with loops of the small bowel and
sigmoid colon. In the female, the extraperitoneal rectum lies
behind the posterior vaginal wall; the intraperitoneal rectum may
be related to the upper part of the vagina, uterus, fallopian
tubes, ovaries, small bowel, and sigmoid colon. Laterally above the
peritoneal reection, there may be loops of small bowel, adnexa, and
sigmoid colon. Below the reection, the rectum is separated from the
side wall of the pelvis by the ureter and iliac vessels. &
PERITONEAL RELATIONS For descriptive purposes the rectum is divided
into upper, middle, and lower thirds. The upper third is covered by
peritoneum anteriorly and laterally, the middle third is cov- ered
only anteriorly, and the lower third is devoid of peritoneum. The
peritoneal reection shows considerable variation between
individuals and between men and women. In men, it is usually 79 cm
from the anal verge, while in women it is 57.5 cm above the anal
verge. The middle valve of Houston roughly corresponds to the ante-
rior peritoneal reection. The posterior peritoneal reection is
usually 1215 cm from the anal verge (Fig. 2). The location of the
peritoneal reection has not been extensively studied in living
patients. Najarian et al. (10) investigated the location of the
peritoneal reection in 50 patients undergoing laparotomy. The
distance from the anal verge to the peritoneal reection was
measured in each patient via simultaneous intraoperative
proctoscopy and intra-abdominal visualization of the peritoneal
reec- tion. The mean lengths of the peritoneal reection were 9 cm
anteriorly, 12.2 cm laterally, and 14.8 cm posteriorly for females,
and 9.7 cm anteriorly, 12.8 cm laterally, and 15.5 cm posteriorly
for males. The lengths of the anterior, lateral, and posterior
peritoneal measurements were statistically different from one
another, regardless of gen- der. Theirs (10) data indicated that
the peritoneal reection is located higher on the rectum than
reported in autopsy studies, and that there is no difference
between males and females. Knowledge of the location and position
of a rectal carcinoma in relationship to the peritoneal reec- tion
will help the surgeon optimize the use of peranal techniques of
resection. & FASCIAL ATTACHMENTS Fascia Propria (Investing
Fascia) The posterior part of the rectum, the distal lateral two
thirds, and the anterior one third, are devoid of peritoneum, but
they are covered with a thin layer of pelvic fascia, called fascia
propria or the investing fascia. At the level of the rec- tal
hiatus, the levator ani is covered by an expansion of the pelvic
fascia, which on reaching the rectal wall divides into an ascending
component, which fuses with the fascia pro- pria of the rectum, and
a descending component, which interposes itself between the
muscular coats forming the conjoint longitudinal coat (11). These
broelastic bers run downward to reach the dermis of the perianal
skin and split the subcutaneous striated sphincter into 812
discrete muscle bundles. 4 & PART I: ESSENTIAL
CONSIDERATIONS
22. Waldeyers Fascia The sacrum and coccyx are covered with a
strong fascia that is part of the parietal pelvic fascia. Known as
Waldeyers fascia, this presacral fascia covers the median sacral
vessels. The rectosacral fascia is the Waldeyers fascia from the
peri- osteum of the fourth sacral segment to the posterior wall of
the rectum (12,13). It is found in 97% of cadaver dissections (13).
Waldeyers fascia contains branches of sacral splanch- nic nerves
that arise directly from the sacral sympathetic ganglion and may
contain branches of the lateral and medi- an sacral vessels. This
fascia should be sharply divided with scissors or electrocautery
for full mobilization of the rectum (Fig. 3). The posterior space
below the rectosacral fascia is the supralevator or retrorectal
space (see Fig. 12). Denonvilliers Fascia Anteriorly, the
extraperitoneal portion of the rectum is covered with a visceral
pelvic fascia, the fascia propria, or investing fascia. Anterior to
the fascia propria, or is a lmy delicate layer of connective tissue
known as Denonvilliers fascia (14). It separates the rectum from
the seminal vesicles and the prostate or vagina (Fig. 4).
Denonvilliers fascia has no macroscopically discernible layers.
Histologically, it is composed of dense collagen, smooth muscle
bers, and coarse elastic bers (15,16). Its attachments have been
surrounded by confusion and debates. Some authors believe it is
adherent to the rectum (1619), others note that it is applied to
the seminal vesicles and the prostate (15,2022). FIGURE 2 &
Peritoneal relations of the rectum. FIGURE 3 & (A) Rectosacral
fascia. (B) Sharp division of rectosacral fascia for full
mobilization of the rectum. CHAPTER 1: SURGICAL ANATOMY &
5
23. Lindsey et al. (23) designed a study to evaluate the
anatomic relation of Denonvilliers fascia: whether it is attached
on the anterior fascia propria of the rectum, or on the seminal
vesicles and prostate. They prospectively col- lected 30 specimens
from males undergoing total mesorectal excision for mid and low
rectal carcinoma, with a deep dissection of the anterior
extraperitoneal rectum to the pelvic oor. The anterior aspects of
the extraperitoneal rectal sections were examined microscopically
for the presence or absence of Denonvilliers fascia. In 20/30
patients that the carcinoma involved anteriorly, 55% vs. 45% of the
specimens had Denonvilliers fascia present. On the other hand, when
the anterior rectum was not involved with carcinoma (10 patients),
90% of the specimens con- tained no Denonvilliers fascia. The
authors concluded, when rectal dissection is conducted on fascia
propria in the anatomic plane, Denonvilliers fascia remains on the
posterior aspect of the prostate and seminal vesicles.
Denonvilliers fascia lies anterior to the anatomic fascia propria
plane of anterior rectal dissection in total mesorectal excision
(TME) and is more closely applied to the prostate than the rectum.
This study has put the debates to rest; Denonvilliers fascia is
more closely applied to the seminal vesicles and the prostate than
the rectum. Lateral Ligament The distal rectum, which is
extraperitoneal, is attached to the pelvic side wall on each side
by the pelvic plexus, connective tissues, and middle rectal artery
(if present) (24). Histologically it consists of nerve structures,
fatty tissue, and small blood vessels (25). Recently, the anatomi-
cal term of lateral ligament has been a subject of debate. In
dissection of 27 fresh cadavers and ve embalmed pelves, Nano et al.
(26) found that lateral ligaments were extension of the mesorectum
to the lateral endopelvic fascia. From their experience with
anatomic dissection applied to surgery, several conclusion were
drawn: & Lateral ligaments are extensions of the mesorectum and
must be cut at their attachment at the endopelvic fascia for TME to
take place. & Lateral ligaments contain fatty tissue in
communication with mesorectal fat and possibly some vessels and
nerve laments that are of little importance. & Insertion of
lateral ligaments at the endopelvic fascia is placed under the
urogenital bundle. & The middle rectal artery courses
anteriorly and infer- iorly in respect to the lateral ligament.
& Lateral ligaments can be cut at their insertion on the
endopelvic fascia without injuring the urogenital ner- vous bundle,
which, however, should be kept in view during this procedure,
because it crosses the middle rec- tal artery and fans out behind
the seminal vesicles. & The lateral aspect of the rectum
receives the lateral pedi- cle, which consists of the nervi recti
and the middle rectal artery. A study by Rutegard et al. (25) on 10
patients who underwent total mesorectal excision for rectal
carcinoma revealed, the often thin structures, usually referred to
as FIGURE 4 & Denonvilliers fascia. 6 & PART I: ESSENTIAL
CONSIDERATIONS
24. the lateral ligaments, seem to arise from the pelvic
plexuses and bridge over into the mesorectum, . . . they can be
iden- tied in almost every patient. The authors contend that the
lateral ligaments are real anatomical ndings. This nd- ing was
supported by Sato and Sato (13) in the dissection of 45 cadavers.
On the other hand, Jones et al. (24) meticulously dissected 28
cadaveric pelves; they found insubstantial thin strands of
connective tissues traversing the space between the mesorectum and
the pelvic side wall. These strands of connective tissues were no
different from those one would expect to nd in any areolar plane.
They were often absent altogether. The pelvic plexuses were
distinct from the middle rectal artery (if present) and had no
association with the connective tissues. Jones et al. (24) believed
that the lateral ligament was nothing more than a surgical arti-
fact that results from injudicious dissection. When the rectum is
pulled medially, the complex of middle rectal artery and vein, the
splanchnic nerves, and their accompanying connective tissues form a
band-like structure extending from the lateral pelvic wall to the
rec- tum (27). This structure was most likely mistaken as the
lateral ligament in the past. Whatever one would call the lateral
attachment of the low rectum, the tissues need to be divided in
full mobilization of the rectum. & MESORECTUM The posterior
rectum is devoid of peritoneum and has no mesorectum. The term
mesorectum is a misnomer and does not appear in the Normina
Anatomica although it is listed in the Normina Embryologica (28).
The word mesorectum was possibly rst used by Maunsell in 1892 and
later popu- larized by Heald of the United Kingdom (28). In
answering the critique of using this word, Heald answered, . . . it
was a surgical word used by the foremost of my surgical teachers
when I was a young registrar. Mr. Rex Lawrice of Guys Hospital used
to describe the process of dividing the mesorectum as was well
described in Rob and Smiths text book of surgery at that time. . .
. no other word seems readily available to describe it (29). Total
mesorectal excision implies the complete exci- sion of all fat
enclosed within the fascia propria, which Heald calls the
mesorectum. This dissection is performed in a circumferential
manner down to the levator muscles (28). Bisset et al. (30)
preferred the term extra fascial exci- sion of the rectum. The term
mesorectum has now been used worldwide and appears well entrenched.
Canessa et al. (31) studied the lymph nodes in 20 ca- devers using
conventional manual dissection. The starting point was at the
bifurcation of the superior rectal artery and ending at the
anorectal ring. They found an average of 8.4 lymph nodes per
rectum; 71% of the lymph nodes were above the peritoneal reection
and 29% were below it. Dissection of seven fresh cadavers on the
mesorectum by Toper et al. (32) yielded 174 lymph nodes; over 80%
of the lymph nodes were smaller than 3 mm. Fifty-six percent of the
nodes were located in the posterior mesentery, and most were
located in the upper two thirds of posterior rectal mesentery.
& HISTOLOGY Knowledge of the microscopic anatomy of the large
intes- tine is of paramount importance in understanding the various
disease processes. This is especially true in the case of
neoplasia, where the depth of penetration will dic- tate the
treatment recommendation. Therefore it is essential to examine
histologic features. The innermost layer is the mucosa, which is
com- posed of three divisions. The rst is a layer of columnar
epithelial cells with a series of crevices or crypts character-
ized by straight tubules that lie parallel and close to one another
and do not branch (glands of Lieberkuhn). The sur- face epithelium
around the openings of the crypts consists of simple columnar cells
with occasional goblet cells. The tubules are lined predominantly
by goblet cells, except at the base of the crypts where
undifferentiated cells as well as enterochromafn and amine
precursor uptake and decarboxylation (APUD) cells are found. The
epithelial layer is separated from the underlying connective tissue
by an extracellular membrane composed of glycopolysac- charides and
seen as the lamina densa of the basement membrane when viewed by
electron microscopy (33). Abnormalities classied as defects,
multilayering, or other structural abnormalities have been reported
in many types of neoplasms, including those of the colon and
rectum. These abnormalities are more common in malignant than in
benign neoplasms. The second division of the mucosa is the lamina
propria, composed of a stroma of connective tissue containing
capillaries, inammatory cells, and lymphoid follicles that are more
prominent in young per- sons. The third division is the muscularis
mucosa, a ne sheet of smooth muscle bers that serves as a critical
demarcation in the diagnosis of invasive carcinoma and includes a
network of lymphatics (34). Beneath the muscularis mucosa is the
submucosa, a layer of connective tissue and collagen that contains
ves- sels, lymphatics, and Meissners plexus. It is the strongest
layer of the bowel. The next layer is the circular muscle, which is
a contin- uous sheath around the bowel, including both the colon
and the rectum. On the external surface of the circular muscle are
clusters of ganglion cells and their ramications; these make up the
myenteric plexus of Auerbach. Unmyelinated postganglionic bers
penetrate the muscle to communicate with the submucosal plexus. The
outer or longitudinal muscle bers of the colon are
characteristically collected into three bundles, called the taeniae
coli; however, in the rectum these bers are spread out and form a
continuous layer. The muscularis propria is pierced at regular
intervals by the main arterial blood supply and venous drainage of
the mucosa. The outermost layer, which is absent in the lower por-
tions of the rectum, is the serosa or visceral peritoneum. This
layer contains blood vessels and lymphatics. & ANAL CANAL The
anal canal is the terminal portion of the intestinal tract. It
begins at the anorectal junction (the point passing CHAPTER 1:
SURGICAL ANATOMY & 7
25. through the levator ani muscles), is about 4 cm long, and
terminates at the anal verge (35,36). This denition differs from
that of the anatomist, who designates the anal canal as the part of
the intestinal tract that extends from the den- tate line to the
anal verge. The anal canal is surrounded by strong muscles, and
because of tonic contraction of these muscles, it is com- pletely
collapsed and represents an anteroposterior slit. The musculature
of the anorectal region may be regarded as two tubes, one
surrounding the other (Fig. 5) (37). The inner tube, being
visceral, is smooth muscle and is inner- vated by the autonomic
nervous system, while the outer funnel-shaped tube is skeletal
muscle and has somatic innervation. This short segment of the
intestinal tract is of paramount importance because it is essential
to the mechanism of fecal continence and also because it is prone
to many diseases. The anatomy of the anal canal and perianal
structures has been imaged using endoluminal magnetic resonance
imaging (38). Investigators found that the lateral canal was
signicantly longer than its anterior and posterior part. The
anterior external anal sphincter was shorter in women than in men
and occupied, respectively, 30% and 38% of the anal canal length.
The median length and thickness of the female anterior external
anal sphincter were 11 and 13 mm, respectively. These small
dimensions explain why a relatively small obstetrical tear may have
a devastating effect on fecal continence and why it may be difcult
to iden- tify the muscle while performing a sphincter repair after
an obstetrical injury. The caudal ends of the external anal sphinc-
ter formed a double layer. The perineal body was thicker in women
than in men and easier to dene. The supercial transverse muscles
had a lateral and caudal extension to the ischiopubic bones. The
bulbospongiosus was thicker in men than in women. The
ischiocavernosus and anococcygeal body had the same dimensions in
both sexes. Posteriorly the anal canal is related to its
surrounding muscle and the coccyx. Laterally is the ischioanal
fossa with its inferior rectal vessels and nerves. Anteriorly in
the male is the urethra, a very important relationship to know
during abdominoperineal resection of the rectum. Anteriorly in the
female are the perineal body and the lowest part of the pos- terior
vaginal wall. & LINING OF CANAL The lining of the anal canal
consists of epithelium of dif- ferent types at different levels
(Fig. 6). At approximately the midpoint of the anal canal there is
an undulating demarcation referred to as the dentate line. This
line is approximately 2 cm from the anal verge. Because the rec-
tum narrows into the anal canal, the tissue above the dentate line
takes on a pleated appearance. These longitu- dinal folds, of which
there are 6 to 14, are known as the columns of Morgagni. There is a
small pocket or crypt at the lower end of and between adjacent
columns of the folds. These crypts are of surgical signicance
because for- eign material may become lodged in them, obstructing
the ducts of the anal glands and possibly resulting in sepsis. The
mucosa of the upper anal canal is lined by colum- nar epithelium.
Below the dentate line the anal canal is lined with a squamous
epithelium. The change, however, is not abrupt. For a distance of
612 mm above the dentate line there is a gradual transition where
columnar, transi- tional, or squamous epithelium may be found. This
area, referred to as the anal transitional or cloacogenic zone, has
extremely variable histology. A color change in the epithelium is
also noted. The rectal mucosa is pink, whereas the area just above
the FIGURE 5 & Anal canal. 8 & PART I: ESSENTIAL
CONSIDERATIONS
26. dentate line is deep purple or plum color due to the under-
lying internal hemorrhoidal plexus. Subepithelial tissue is loosely
attached to and radially distensible from the inter- nal
hemorrhoidal plexus. Subepithelial tissue at the anal margin, which
contains the external hemorrhoidal plexus, forms a lining that
adheres rmly to the underlying tissue. At the level of the dentate
line, the lining is anchored by what Parks (39) called the mucosal
suspensory ligament. The perianal space is limited above by this
ligament and below by the attachment of the longitudinal muscle to
the skin of the anal verge. The area below the dentate line is not
true skin because it is devoid of accessory skin struc- tures
(e.g., hair, sebaceous glands, and sweat glands). This pale,
delicate, smooth, thin, and shiny stretched tissue is referred to
as anoderm and runs for approximately 1.5 cm below the dentate
line. At the anal verge the lining becomes thicker and pigmented
and acquires hair follicles, glands, and other histologic features
of normal skin (2). In this circumanal area there is also a
well-marked ring of apocrine glands, which may be the source of the
clinical condition called hidradenitis suppurativa. Proximal to the
dentate line the epithelium is supplied by the autonomic nervous
system, while distally the lining is richly inner- vated by the
somatic nervous system (40). & ANAL TRANSITIONAL ZONE The anal
transitional zone (ATZ) is interposed between uninterrupted
colorectal type mucosa (columnar) above and uninterrupted squamous
epithelium (anoderm) below, irrespective of the type of epithelium
present in the zone itself (41). The ATZ usually commences just
above the dentate line. Using computer maps of histology, Thompson-
Fawcett et al. (42) found that the dentate line was situated at a
median of 1.05 cm above the lower border of the inter- nal
sphincter. This is much smaller than the study by Fenger (41),
which portrayed the ATZ extending 0.9 cm above the dentate line.
Fenger used the traditional Alcian blue stain. This results in
overestimation of the length of the ATZ because the pale blue
staining is due to staining of supercial nuclei of both squamous
anoderm and transi- tional epithelium rather than staining of
mucin-producing cells in the transitional epithelium (42). The ATZ
is much smaller than commonly thought. The histology of the ATZ is
extremely variable. Most of the zone is covered by ATZ epithelium,
which appears to be composed of four to nine cell layersthe basal
cells, columnar, cuboidal, unkeratinized squamous epithelium, and
anal glands. The ATZ epithelium contains a mixture of sulphomucin
and sialomucin. The mucin pattern in the columnar variant of the
ATZ epithelium and in the anal canal is of the same type and
differs from that of colorec- tal-type epithelium. The ndings of a
similar mucin pattern in mucoepidermoid carcinoma and in some cases
of carci- noma arising in anal stulas as well as in carcinoma
suspected of arising in anal glands might indicate a com- mon
origin of the neoplasm in the ATZ epithelium. Histochemical study
shows that endocrine cells have been demonstrated in 87% of
specimens. Their function is unknown. Melanin is found in the basal
layer of the ATZ epithelium in 14% of specimens. Melanin cannot be
demon- strated in the anal gland but is a constant nding in the
squamous epithelium below the dentate line, increasing in amount as
the perianal skin is approached. The melanin- containing cells in
the ATZ seem a reasonable point of origin for melanoma, as do the
ndings of junctional activ- ity and atypical melanocyte hyperplasia
in the ATZ. The ATZ epithelium has a dominating diploid popu-
lation, although there was a small hyperdiploid peak representing
nuclei with a scattered volume considerably higher than that of the
main diploid population. This was present regardless of the
histologic variant (columnar or cuboid) of the ATZ epithelium.
Tetraploid or octoploid populations are not found (41). & ANAL
GLANDS The average number of glands in a normal anal canal is six
(range, 310) (43). Each gland is lined by stratied columnar
epithelium with mucus-secreting or goblet cells interspersed within
the glandular epithelial lining and has a direct opening into an
anal crypt at the dentate line. Occasionally, two glands open into
the same crypt, while half the crypts have no communication with
the glands. FIGURE 6 & Lining of the anal canal. CHAPTER 1:
SURGICAL ANATOMY & 9
27. These glands were rst described by Chiari in 1878 (44). The
importance of their role in the pathogenesis of stulous abscess was
presented by Parks in 1961 (37). Seow-Choen and Ho (43) nd that 80%
of the anal glands are submucosal in extent, 8% extend to the
internal sphincter, 8% to the conjoined longitudinal muscle, 2% to
intersphincteric space, and 1% penetrate the external sphincter.
The anal glands are fairly evenly distributed around the anal
canal, although the greatest number are found at the anterior
quadrant. Mild to moderate lympho- cytic inltration is noted around
the anal glands and ducts; this is sometimes referred to as anal
tonsil. In an autopsy study of 62 specimens, Klosterhalfen et al.
(45) found that nearly 90% of specimens contained anal sinuses. In
fetuses and children, more than half the anal sinuses were
accompanied by anal intramuscular glands penetrating the internal
anal sphincter, whereas in adult specimens, anal intramuscular
glands were rare. & MUSCLES OF THE ANORECTAL REGION &
INTERNAL SPHINCTER MUSCLE The downward continuation of the
circular, smooth muscle of the rectum becomes thickened and rounded
at its lower end and is called the internal sphincter. Its lowest
portion is just above the lowest part of the external sphincter and
is 11.5 cm below the dentate line (Fig. 5). & CONJOINED
LONGITUDINAL MUSCLE At the level of the anorectal ring, the
longitudinal muscle coat of the rectum is joined by bers of the
levator ani and puborectalis muscles. Another contributing source
is the pelvic fascia (11). The conjoined longitudinal muscle so
formed descends between the internal and external anal sphincters
(Fig. 5) (46). Many of these bers traverse the lower portion of the
external sphincter to gain insertion in the perianal skin and are
referred to as the corrugator cutis ani (47). Fine and Lawes (48)
described a longitudinal layer of muscle lying on the inner aspect
of the internal sphincter and named it the muscularis submucosae
ani. These bers may arise from the conjoined longitudinal muscle.
Some bers that traverse the internal sphincter muscle and become
inserted just below the anal valves have been referred to as the
mucosal suspensory ligament (37). Some bers may traverse the
external sphincter to form a transverse septum of the ischioanal
fossa (Fig. 5). In a review of the anatomy and function of the anal
longi- tudinal muscle, Lunnis and Phillips (49) speculated that
this muscle plays a role as a skeleton supporting and bind- ing the
internal and external sphincter complex together, as an aid during
defecation by everting the anus, as a support to the hemorrhoidal
cushions, and as a determining factor in the ramication of sepsis.
& EXTERNAL SPHINCTER MUSCLE This elliptical cylinder of
skeletal muscle that surrounds the anal canal was originally
described as consisting of three distinct divisions: the
subcutaneous, supercial, and deep portions (36). This account was
shown to be invalid by Goligher (50), who demonstrated that a sheet
of muscle runs continuously upward with the puborectalis and leva-
tor ani muscles. The lowest portion of the external sphincter
occupies a position below and slightly lateral to the internal
sphincter. A palpable groove at this level has been referred to as
the intersphincteric groove. The lowest part (subcutaneous bers) is
traversed by the conjoined longitudinal muscle, with some bers
gaining attachment to the skin. The next portion (supercial) is
attached to the coccyx by a posterior extension of muscle bers that
combine with connective tissue, forming the anococcygeal ligament.
Above this level, the deep portion of the external sphincter is
devoid of posterior attachment and proximally becomes continuous
with the puborectalis muscle. Ante- riorly, the high bers of the
external sphincter are inserted into the perineal body, where some
merge and are continu- ous with the transverse perineal muscles.
The female sphincter has a variable natural defect occurring along
its anterior length (51). This makes interpretation of the isolated
endoanal ultrasound difcult and explains overre- porting of
obstetric sphincter defects. The external sphincter is supplied by
the inferior rectal nerve and a perineal branch of the fourth
sacral nerve. From their embryolic study, Levi et al. (52)
demonstrated that the external sphincter is subdi- vided into two
parts, one supercial and one deep without any connection with the
puborectalis. Shak (46) has suggested that the anal sphincter
mechanism consists of three U-shaped loops and that each loop is a
separate sphincter and complements the others to help maintain
continence (Fig. 7). This concept has not been generally accepted.
In fact, more recently Ayoub (56) found that the external sphincter
is one muscle mass, not divided into layers or laminae, and that
all bers of the external sphincter muscles retain their skeletal
attachment by the anococcygeal ligament to the coccyx. Clinical
experience supports Ayoubs concept; we have not been able to
identify Shaks three-part scheme. Indeed, during posta- nal repairs
for anal incontinence, the external sphincter, puborectalis, and
levator ani muscles present as one contin- uous funnel-shaped sheet
of skeletal muscle. The currently accepted perception of the
arrangement of the external FIGURE 7 & Shak loops. Source: From
Ref. 46. 10 & PART I: ESSENTIAL CONSIDERATIONS
28. sphincter is that it is one continuous circumferential
mass, a concept in accordance with a study in which anal endoso-
nography was used (53). & PERINEAL BODY The perineal body is
the anatomic location in the central portion of the perineum where
the external sphincter, bulbocavernosus, and supercial and deep
transverse peri- neal muscles meet (Fig. 8). This tends to be a
tendinous intersection and is believed to give support to the
perineum