Anal and rectal diseases explained - part 1 pdf

1.1 Anal and rectal anatomy 3General information Chapter 1 This is trial version www.adultpdf.com... Rectosigmoid colon Free tenia tenia libera Anal and rectal anatomy Chapter 1.1 This i

Perianal and rectal complaints are among the most common seen by

primary care physicians, surgeons, and gastroenterologists

However, the wide variety of disorders associated with these

complaints are, in general, poorly understood Illustrated throughout

with color images and exquisitely detailed line diagrams, Anal and

Rectal Diseases Explained provides a practical introduction to the

presentation, diagnosis, and management of a broad range of anal

and rectal diseases

"What a great idea! This book will be a wonderful resource for

clinicians Every physician should have a copy on their shelf!”

Dr Sunanda Kane, Department of Medicine,

Gastroenterology Division, University of Chicago

About the author

Eli D Ehrenpreis, MD, is Assistant Professor of Medicine at Rush

Presbyterian St Luke's Medical Center in Chicago, Illinois, and a

practicing gastroenterologist at Adult Care Specialists, Arlington

Heights, Illinois Dr Ehrenpreis is the former director of the training

fellowship program in gastroenterology at the University of Chicago

and has also served as a staff physician at Cleveland Clinic, Florida

He is the author of more than 60 clinical research papers in the fields

of gastroenterology and clinical pharmacology and has authored a

number of chapters in gastroenterology, colorectal surgery, and critical

care medicine textbooks Dr Ehrenpreis is married with three children,

and lives in Skokie, Illinois

9 781901 346671

I S B N 1 - 9 0 1 3 4 6 - 6 7 - 6

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Anal and rectal

diseases explained

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Remedica Explained series

Common spinal disorders explained

Nuclear medicine explained

While every effort is made by the publishers to see that no inaccurate or misleading data, opinions, or statements appear in this book, they wish to make it clear that the material contained in the publication represents a summary

of the independent evaluations and opinions of the authors and contributors As a consequence, the authors, publisher, and any sponsoring company accept no responsibility for the consequences of any inaccurate or misleading data or statements Neither do they endorse the content of the publication or the use of any drug or device in a way that lies outside its current licensed application in any territory.

Published by the Remedica Group

Remedica Publishing, 32–38 Osnaburgh Street, London, NW1 3ND, UK

Remedica Inc, Tri-State International Center, Building 25, Suite 150,

Lincolnshire, IL 60069, USA

Email: books@remedica.com

www.remedica.com

Publisher: Andrew Ward

In-house editor: Tamsin White

© October 2003 Remedica Publishing

All rights reserved No part of this publication may be reproduced,

stored in a retrieval system or transmitted in any form or by any means,

electronic, mechanical, photocopying, recording or otherwise, without

the prior permission of the publisher.

ISBN 1 901346 67 6

British Library Cataloguing in-Publication Data

A catalogue record for this book is available from the British LibraryThis is trial version

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Anal and rectal

diseases explained

Eli D Ehrenpreis, MD

Assistant Professor of Medicine

Rush Presbyterian St Luke's Medical Center

Adult Care Specialists

Arunas Gasparitus, MD, for providing many interesting and

unusual radiographs for the book

Charles Dye, MD, for providing endoscopic ultrasound images.Sunanda V Kane, MD, for providing endoscopic photos for theCrohn’s disease section

Andrew Ward for encouraging me to write the book and providingpublication support

Tamsin White for editorial assistance

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This book gives a clear and detailed overview of some of the different anorectal andcolonic pathologies Although some of these conditions are very common in ourpatient population, our knowledge and our experience in managing theseconditions is sometimes lacking The aim of this book is to provide clinicians with

a tool for rapid consultation and a source of information in order to properlyanswer the patient’s questions Each section clearly describes the condition withup-to-date management guidelines and some very precious clinical pearls.Each topic is outlined in a multidisciplinary fashion with the medical, surgical, andpathological aspects clearly detailed in each section Such a succinct overview haslong been needed The format is very clear and certainly this will be a book to have

on a ward, in the doctor’s office, or on the shelves at home

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3.1 Anal fissure 493.2 Anal stenosis 533.3 Anorectal abscess 553.4 Constipation 593.5 Fecal incontinence 653.6 Hemorrhoids 693.7 Hidradenitis suppurativa 753.8 Nonrelaxing puborectalis syndrome 773.9 Perianal Crohn’s disease 793.10 Perianal fistula 833.11 Proctalgia fugax 873.12 Pruritus ani 893.13 Radiation proctopathy 933.14 Rectal prolapse 973.15 Rectovaginal fistula 1013.16 Solitary rectal ulcer syndrome 1033.17 Ulcerative proctitis 105

4.1 Anal carcinoma 1114.2 Other anal malignanciesThis is trial version 115www.adultpdf.com

5 Neoplasms of the rectum

5.1 Rectal carcinoma 1215.2 Staging of rectal cancer 1255.3 Surgery for rectal cancer 1295.4 Medical therapy for rectal cancer 1315.5 Other rectal malignancies 133

6.1 Chlamydia and lymphogranuloma venereum 1396.2 Gonorrhea 1416.3 Herpes simplex 1436.4 HIV-associated anorectal disease 1456.5 Syphilis 1476.6 Venereal warts (condylomata acuminata) 149

7.1 Diarrhea 1557.2 Fecal impaction 1597.3 Ileoanal pouch anastomosis 1617.4 Pilonidal sinuses 1677.5 Rectal foreign bodies 169

8.1 Anal fissure 1738.2 Fecal incontinence 1758.3 Hemorrhoids 1778.4 Kegel exercises 1798.5 Nonrelaxing puborectalis syndrome 1818.6 Perianal Crohn’s disease 1858.7 Pruritus ani 1898.8 Radiation proctopathy 1918.9 Rectal prolapse 1938.10 Solitary rectal ulcer syndrome 1958.11 Ulcerative proctitis 1978.12 Venereal warts 199

1.1 Anal and rectal anatomy 3

General information

Chapter 1

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Anal canal

The anal canal is the terminal portion of the gastrointestinal tract It is the shorttubular segment, distal to the rectum, which is lined internally by squamous andtransitional epithelium The anal canal begins where the distal rectum penetrates themuscular floor of the pelvic cavity It is surrounded by the anal sphincter muscle

Levator ani muscle

Fibrous septum Corrugator cutis ani muscle Perianal skin

Figure 1 Rectal muscular anatomy.

Rectosigmoid

colon Free tenia (tenia libera)

Anal and rectal anatomy

Chapter 1.1

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Chapter 1

4

12–15 cm in length The lower third of the rectum is distal to the peritonealreflection Unlike in the rest of the colon, longitudinal muscle fibers in the rectum

do not form discrete lengthwise bands (teniae) but, instead, surround the entire

rectum (see Figure 1) The dentate line marks the distal portion of the rectum and separates it from the anal canal (see Figure 2) It also separates two types of

epithelia, the simple columnar epithelium of the rectum and the stratifiedepithelium of the anal canal (anoderm) The dentate line has multiple folds calledthe columns of Morgagni The anal crypts and glands are located at the base of thecolumns of Morgagni These glands may be the site of perianal abscess and fistulaformation The rectum has three folds, called the valves of Houston

Musculature

Internal anal sphincter

The internal anal sphincter is a thick ring of fibers from the circular smooth muscle

of the colon at the proximal portion of the anal canal (see Figure 3).

External anal sphincter

The external anal sphincter surrounds the anal canal at the pelvic diaphragm, distal

to the anal orifice (see Figure 3) The external anal sphincter is a ring of skeletal

muscle, which extends superiorly to the puborectalis, an important constituent ofthe levator ani, the main muscle of the pelvic floor Posteriorly, the external analsphincter has attachments to the coccyx and, anteriorly, to the perineal body Thepuborectalis muscle attaches anteriorly to the pubic bone and envelops the lowerrectum posteriorly, forming a sling The puborectalis muscle is responsible for the

anorectal angle (see Section 1.2: The normal process of defecation).

Innervation

Internal anal sphincter

Extrinsic autonomic fibers of both the sympathetic and parasympathetic nervoussystems innervate the internal anal sphincter

External anal sphincter

The pudendal nerve (sacral nerve roots S3 and S4) innervates the external anal

sphincter, the levator ani, and the puborectalis muscles (see Figure 4).

Rectum

The rectum is innervated by the sympathetic nervous system via the pelvic plexus(L1, L2, and L3), and the parasympathetic nervous system via the nervi erigentes(S2, S3, and S4)

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Anal and rectal anatomy

5

Anal gland

Anal crypt

Dentate line

Column of Morgagni

Figure 2 Anatomy of the anal region

Figure 3 Anal muscular anatomy.

Rectal fascia

Longitudinal muscle of rectum

Intersphincteric groove (anocutaneous line)

Arterial

Arterial supply to the rectum occurs via the superior rectal, middle rectal, and

inferior rectal arteries (see Figure 5) The superior rectal artery is a branch of the

inferior mesenteric artery The middle rectal artery originates from the internal iliac

Sacrotuberous ligament

Inferior rectal nerve

Sacrospinous ligament

S2 S3 S4

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or the pudendal artery, and the inferior rectal artery originates from the internaliliac artery The majority of the blood supply is from the superior and inferiorrectal arteries.

Anal and rectal anatomy

Left colic

Tributaries

of left and right superior rectal veins Perimuscular rectal venous plexus Left middle rectal vein Left internal pudendal vein

in pudendal canal (Alcock) External rectal venous plexus

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The neuromuscular anatomy of the anus and rectum is “designed” to preserve fecalcontinence and to facilitate defecation: withholding stool until it is appropriate todefecate and propelling stool at the time of defecation.

The puborectalis muscle remains tonically contracted at rest to form the anorectalangle, a sharp angulation (normally approximately 90°), which blocks stool from

exiting out of the rectum (see Figures 1 and 2) The anal sphincters further

function to provide a barrier for the passage of air, fluid, or solid stool to exit out

of the anal canal

Figure 1 The pull of the puborectalis anteriorly towards the pubis muscle contributes

to the angulation between the rectum and anal canal termed the anorectal angle

(dashed line)

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Figure 2 Normal dynamic proctogram (A) at rest and (B) straining demonstrating

straightening of the anorectal angle

When stool enters the rectum (which is a highly compliant organ), it distends andthe internal anal sphincter (which is normally contracted) relaxes while the externalanal sphincter remains closed This process is called the rectoanal inhibitory reflexand is defective in Hirschsprung’s disease When stool is present in the rectum butdefecation is not to be initiated, the puborectalis muscle and external analsphincter remain contracted At the appropriate time for defecation, thepuborectalis muscle relaxes and the anorectal angle increases, contraction of thediaphragm and abdominal muscles increases interabdominal pressure, relaxation

of the external anal sphincter occurs, and feces are passed in conjunction with

contraction of the rectum (see Figure 3) Increased contraction of the puborectalis

muscle and external anal sphincter will occur when there is sensation of stoolwithin the anal canal and voluntary defecation has not been initiated

The normal process of defecation

11

Figure 3 The process of defecation

(A) Puborectalis and external

sphincter are contracted at rest.

(B) With entry of stool into the

rectum, the puborectalis and anal sphincters relax; the levator ani, rectus muscles, and diaphragm

contract (C) With defecation, the

external anal sphincter relaxes; there is a rectal contraction

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