Atlas of Colonoscopy E-Book

Helmut Messmann

• Herausgeber: Thieme
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 478

Veröffentlichungsjahr: 2005

Beschreibung

A complete guide to colonoscopy featuring more than 1,000 superb illustrations! In recent decades, colonoscopy has developed into one of the most essential techniques for early screening, detection, and diagnosis of colorectal cancer, inflammatory bowel disease, and other disorders. And rapid advances in interventional endoscopy offer doctors and patients an ever-increasing array of treatment possibilities. For newcomers to the technique and advanced practitioners alike, this lavishly illustrated atlas is a state-of-the-art guide to total colonoscopy. Atlas of Colonoscopy is... Accessible: Expert authors present all of the necessary instruments and examination techniques, as well as guidelines on preparation, related medications, complications, and more. Tips and tricks for instrument insertion and guidance Illustrated, thorough descriptions of normal findings in all colon segments A logical structure and easy-to-use-layout Practical: Detailed descriptions and multiple illustrations of numerous pathological findings Endoscopic criteria and differential diagnoses for all major diseases Useful guide to examination procedures depending on clinical findings Detailed: Coverage of the complete spectrum of interventional colonoscopy, including polypectomy, mucosectomy, tumor treatment, removing foreign objects, treating fistulas, and suture insufficiency Indications and success rates of various treatments, including thermocoagulation, injection, and mechanical treatments Compiled by a team of experts with decades of combined experience in the field, the Atlas of Colonoscopy is an essential resource for anyone working in an endoscopy unit.

Leseprobe

Atlas of Colonoscopy

Techniques • Diagnosis • Interventional Procedures

Helmut Messmann, M.D.

Professor and Medical Director

III Medical Clinic

Augsburg Clinic

Augsburg, Germany

With contributions by

Jürgen Barnert

Max Bittinger

Thomas Eberl

Reinhard Fleischmann

Gertrud Jechart

Andreas Probst

Reinhard Scheubel

Werner Schmidbaur

1055 Illustrations

Thieme

Stuttgart · New York

Library of Congress Cataloging-in-Publication Data

Messmann, Helmut.

Lehratlas der Koloskopie. [English]

Atlas of colonoscopy: examination techniques and diagnosis / Helmut Messmann, with contributions by Jürgen Barnert... [et al.]; [translator, Stefanie Kramer].

p.; cm.

Includes index.

ISBN 3-13-140571-6 (alk. paper) -- ISBN 1-58890-431-8 (alk. paper)

1. Colonoscopy--Atlases.

[DNLM: 1. Colonoscopy--methods--Atlases. 2. Intestinal Diseases--diagnosis--Atlases. 3. Intestinal Diseases--surgery--Atlases. WI 17 M585L 2006] I. Barnert, Jürgen. II. Title.

RC804.C64M47 2006

616.3'407545--dc22

2005020351

This book is an authorized and revised translation of the German edition published and copyrighted 2004 by Georg Thieme Verlag, Stuttgart, Germany. Title of the German edition: Lehratlas der Koloskopie - Das Referenzwerk zur Untersuchungs-technik und Befundinterpretation

Translator: Stefanie Kramer, B.A., Dipl. Trans., IoL, Berlin

© 2006 Georg Thieme Verlag,

Rüdigerstrasse 14, 70469 Stuttgart, Germany

http://www.thieme.de

Thieme New York, 333 Seventh Avenue,

New York, NY 10001 USA

http://www.thieme.com

Printed in Germany

Illustrator: Karin Baum, Mannheim

Typesetting by primustype Hurler GmbH, Notzingen

Printed in Germany by Karl Grammlich GmbH, Pliezhausen

ISBN 3-13-140571-6 (GTV)

ISBN 1-58890-431-8 (TNY)

1 2 3 4 5 6

Important note: Medicine is an ever-changing science undergoing continual development. Research and clinical experience are continually expanding our knowledge, in particular our knowledge of proper treatment and drug therapy. Insofar as this book mentions any dosage or application, readers may rest assured that the authors, editors, and publishers have made every effort to ensure that such references are in accordance with the state of knowledge at the time of production of the book. Nevertheless, this does not involve, imply, or express any guarantee or responsibility on the part of the publishers in respect to any dosage instructions and forms of applications stated in the book. Every user is requested to examine carefully the manufacturers' leaflets accompanying each drug and to check, if necessary in consultation with a physician or specialist, whether the dosage schedules mentioned therein or the contraindications stated by the manufacturers differ from the statements made in the present book. Such examination is particularly important with drugs that are either rarely used or have been newly released on the market. Every dosage schedule or every form of application used is entirely at the user's own risk and responsibility. The authors and publishers request every user to report to the publishers any discrepancies or inaccuracies noticed. If errors in this work are found after publication, errata will be posted at www.thieme.com on the product description page.

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This book, including all parts thereof, is legally protected by copyright. Any use, exploitation, or commercialization outside the narrow limits set by copyright legislation, without the publisher's consent, is illegal and liable to prosecution. This applies in particular to photostat reproduction, copying, mimeographing, preparation of microfilms, and electronic data processing and storage.

Preface

Flexible colonoscopy is now nearly fifty years old. In 1957, the first attempts at constructing a flexible colonoscope were made in Japan by Matsunaga and Hirosaki.

Now, almost half a century later, colonoscopy has become a vital part of gastroenterology. Advancements in recent years— especially in chip technology—have led to previously unseen standards in image quality, which continues to gain in importance, especially in combination with new staining techniques. In addition to the enormous significance of diagnostic colonoscopy, interventional colonoscopy also plays a major role in gastroenterological endoscopy. New techniques have enabled the removal of increasingly larger polyps by means of mucosectomy, without the need for surgical intervention. Measures for achieving hemostasis, managing anastomotic leakages, and placing decompression tubes are also part of a more conservative approach using minimally invasive endoscopy, and increasingly avoiding surgical intervention.

The endoscopy team at the Augsburg Clinic in Augsburg, Germany performs more than 13 000 endoscopies per year, including a large number of interventions, providing us with a wealth of experience to draw on and the source of inspiration for writing this book. Additionally, we used only the latest equipment in creating this book—including zoom endoscopy—in order to produce pictures of superior image quality.

This book is aimed at health-care professionals who are interested in learning more about colonoscopy. However, it also of interest for the experienced gastroenterologist who is already familiar with colonoscopy, providing useful tips and tricks organized by experienced physicians in an informative and instructive manner. It is my hope that we can provide our readers with a good atlas, filled with numerous interesting findings and pictures, to support learning and further education in the area of colonoscopy.

We hope you enjoy reading this volume and look forward to receiving any comments or suggestions that may assist us in continuing to offer our colleagues a top-quality book.

Helmut Messmann

The Augsburg endoscopy team (from left to right):

Dr. G. Jechart, Dr. A. Probst, Dr. R. Fleischmann, Dr. W. Schmidbaur, Dr. M. Bittinger,

Dr. T. Eberl, Dr. R. Scheubel, Dr. J. Barnert, Professor Dr. H. Messmann

List of Contributors

Jürgen Barnert, M.D.III Medical ClinicAugsburg ClinicAugsburg, Germany

Max Bittinger, M.D.III Medical ClinicAugsburg ClinicAugsburg, Germany

Thomas Eberl, M.D.III Medical ClinicAugsburg ClinicAugsburg, Germany

Reinhard Fleischmann, M.D.Assistant ProfessorIII Medical ClinicAugsburg ClinicAugsburg, Germany

Gertrud Jechart, M.D.III Medical ClinicAugsburg ClinicAugsburg, Germany

Helmut Messmann, M.D.ProfessorIII Medical ClinicAugsburg ClinicAugsburg, Germany

Andreas Probst, M.D.III Medical ClinicAugsburg ClinicAugsburg, Germany

Reinhard Scheubel, M.D.III Medical ClinicAugsburg ClinicAugsburg, Germany

Werner Schmidbaur, M.D.III Medical ClinicAugsburg ClinicAugsburg, Germany

Contents

I   General Information

1   General Information Regarding Examination

G. Jechart

Introduction

Indications and Contraindications

Preparing for the Examination

Complications and Risks

General Principles

Anatomy of the Colon

2   Basic Examination Technique and Colonoscopy Workstation

G. Jechart

Learning Examination Technique

Instrument Features

Operating the Endoscope

Simulators

Training on a Patient

The Colonoscopy Workstation

Examination Room Set-up

Hygiene Standards for Reprocessing Equipment

Radiography Equipment Regulations

3   Modern Endoscopic Techniques

M. Bittinger

Digital Structure Enhancement

Magnifying or Zoom Endoscopy

Chromoendoscopy

Fluorescence Endoscopy

II   Normal Examination Procedure and Non-pathological Findings

4   Before the Examination

A. Probst

Informing the Patient

Sedation and Medication

Sedation and Analgesics

Other Medications/Endocarditis Prophylaxis

Patients with Pacemakers or Metal Implants

Positioning the Patient

Safety of the Patient and Monitoring

5   Inserting the Endoscope and Advancing It in the Colon

A. Probst

Inspection and Palpation

Passing the Anal Sphincter

Endoscope Insertion in Postoperative Patients (Colostomy/Ileostomy)

Advancing the Endoscope in the Sigmoid Colon (Sigmoidoscopy)

Advancing Further to the Hepatic Flexure

Proximal Colon

Intubating the Ileocecal Valve and Terminal Ileum

Looping and Using External Compression Techniques

Applying Simple Pressure over the Sigmoid Colon in the Left Lateral Position

Simple and Combined Pressure with Patient in the Supine Position

Transverse Pressure

Pressure on the Right Flank

Pressure over the Cecum

Localizing the Endoscope

Withdrawing the Endoscope and “Blind Spots”

Retroflexion in the Rectum

6   Normal Appearance of the Intestinal Segments

M. Bittinger

Normal Rectum

Normal Sigmoid Colon

Normal Descending Colon

Normal Transverse Colon

Normal Ascending Colon

Normal Cecum and Ileocecal Valve

Normal Terminal Ileum

7   Normal Postoperative Appearances

M. Bittinger

Restoring Intestinal Continuity

III   Pathological Findings

8   Diverticulosis and Diverticulitis

M. Bittinger

Definitions

Diverticulosis

Clinical Picture

Diagnosis

Complications

Differential Diagnosis

Treatment

Diverticulitis

Clinical Picture

Diagnosis

Complications

Differential Diagnosis

Treatment

9   Polyps and Polyposis Syndromes

T. Eberl

Polyps

Definition

Clinical Picture and Clinical Significance

Diagnosis

Epithelial Polyps

Nonepithelial Polyps

Surveillance

Polyposis Syndromes

Definition

Clinical Picture and Clinical Significance

Endoscopic Diagnosis

Familial Adenomatous Polyposis (FAP)

Peutz-Jeghers Syndrome

Juvenile Polyposis

Differential Diagnosis

10   Malignant Tumors

T. Eberl

Definition and Classification

Clinical Picture and Clinical Significance

Diagnosis

Epithelial Tumors

Malignant Nonepithelial Tumors

Surveillance

11   Submucosal Tumors

T. Eberl

Definition and Classification

Clinical Picture and Clinical Significance

Diagnosis

Nonepithelial Tumors

Carcinoids

Treatment

12   Colitis—Inflammatory Bowel Diseases and Other Forms of Colitis

R. Scheubel

Definition

Clinical Significance of Chronic Inflammatory Bowel Disease (IBD)

Diagnosis

Inflammatory Bowel Disease-Indications for Ileocolonoscopy:

Ulcerative Colitis

Pouchitis

Toxic Megacolon

Carcinoma in Ulcerative Colitis

Crohn Disease

Differential Diagnosis of Chronic IBD Types and Other Forms of Inflammatory Bowel Diseases

Differential Diagnosis: Ulcerative Colitis vs. Crohn Disease

Other Differential Diagnoses

Indeterminate Colitis

Infectious Colitis

Radiation Colitis

Ischemic Colitis

NSAID Colitis

Diversion Colitis

Pseudomembranous Colitis

Other Rare Forms of Colitis

Nonclassifiable Types of Colitis

13   Acute and Chronic Lower Gastrointestinal Bleeding

J. Barnert

Definitions

Epidemiology

Prognosis and Clinical Course

Diagnosis

Endoscopic Diagnosis

Chronic Lower Gastrointestinal Bleeding

Acute Lower Gastrointestinal Bleeding

Differential Diagnosis of Acute Lower Gastrointestinal Bleeding

Diverticula

Vascular Causes

Dieulafoy Ulcer

Ischemia

Colitis

Neoplasias

Anorectal Diseases

14   Vascular Malformations and Other Vascular Lesions

J. Barnert

Definitions

Angiodysplasia (Telangiectasia)

Epidemiology and Pathogenesis

Histology

Clinical Course and Prognosis

Diagnosis

Differential Diagnosis

Syndromes/Vascular Malformations in Other Diseases

Hemangiomas

Epidemiology

Histology

Course and Prognosis

Diagnosis

Syndromes/Vascular Malformations in Other Diseases

15   Melanosis Coli

R. Fleischmann

Definition

Clinical Picture

Diagnosis

Therapy

Surveillance

16   Solitary Rectal Ulcer Syndrome

R. Fleischmann

Definition

Clinical Picture

Diagnosis

Treatment

17   Rare Diseases and Disorders

R. Fleischmann

Extrinsic Compression (Stenosis)

Postoperative Strictures and Suture Granulomas

Lumen Dilation and Pseudo-obstruction

Definition

Clinical Picture

Diagnosis

Treatment

Surveillance

Acute Segmental Hemorrhagic Colitis

Definition

Clinical Picture

Diagnosis

Treatment

Surveillance

Pneumatosis Cystoides Intestinalis

Definition

Clinical Picture

Diagnosis

Treatment

Surveillance

Kaposi Sarcoma

Definition

Diagnosis

Treatment

Surveillance

HIV-Related Lymphoma

Ileitis

Colon Varices and Portal Colopathy

Rectal Varices

Iatrogenic Lesions

Lipomas and Carcinoid Tumors

Endometriosis

Amyloidosis

Collagenous Colitis and Microscopic Colitis

Colon Involvement in Non-Hodgkin Lymphoma

IV   Endoscopic Intervention

18   Polypectomy and Mucosectomy

T. Eberl

Indications and Contraindications

Preparing for Polypectomy and Mucosectomy

Instrumentation

Polypectomy

Small Polyps

Stalked Polyps

Sessile Polyps

Malignant Polyps

Mucosectomy

Recovering Resected Polyps

Complications following Polypectomy or Mucosectomy

Follow-up Surveillance after Polypectomy

19   Interventional Tumor Therapy

R. Fleischmann

Pathology of Malignant Colon Tumors

Indications for Endoscopic Tumor Therapy

Hemostasis Methods and Relief of Obstruction

Palliative Tumor Therapy in Inoperable Patients

Laser

APC (Argon Plasma Coagulation)

Metallic Mesh Stents

20   Hemostasis

J. Barnert

Thermocoagulation

Monopolar and Biopolar Electrocoagulation

Argon Plasma Coagulation (APC)

Laser

Heater Probe

Injection Therapy

Mechanical Methods

Hemoclips

Band Ligation

Endoloop

21   Management of Benign Strictures

R. Scheubel

Definition and Causes

Diagnosis and Therapy

22   Fistulas and Postoperative Leakages

W. Schmidbaur

Fistulas

Anastomotic Leakage

Diagnosis

Endoscopic Interventions

Fistula Closure and Management of Dehiscence Using Fibrin Sealant

Fistula Closure and Management of Dehiscence Using Clips

Differential Therapy Using Fibrin Sealant/Clips

Stents

Endoscopic Suturing

EndoVAC

23   Removal of Foreign Bodies

W. Schmidbaur

Principles of Endoscopic Foreign Body Removal

Removal of Foreign Bodies in the Colon

Ingested Foreign Bodies

Iatrogenic Foreign Bodies

Foreign Bodies Introduced Per Rectum

Removal of Foreign Bodies in the Rectum

24   Decompression Tube Placement

J. Barnert

Definitions

Acute Pseudo-obstruction of the Colon

Definition and Pathogenesis

Clinical Picture and Course

Therapy

Mechanical Obstruction

Volvulus

Malignant and Benign Stenoses

Index

I General Information

1    General Information RegardingExamination

2    Basic Examination Technique andColonoscopy Workstation

3    Modern Endoscopic Techniques

1

General Information Regarding Examination

G. Jechart

Introduction

In the thirty years since 1971 when total colonoscopy was first described (16), significant technical advancements have been made in terms of instrument handling and imaging capability. Nevertheless, colonoscopy remains a procedure requiring manual dexterity and concentration. The experienced examiner can now successfully reach the cecum in 98% of patients and in most cases can also reach the terminal ileum. Difficulties can be posed by a mobile and elongated sigmoid colon or transverse colon as well as by postoperative intestinal fixations and other adhesions. The entire examination generally takes around 30 minutes. Rapid advancement and inspection up to the cecum is desirable, considering the discomfort to the patient, though a careful examination of all colon segments when withdrawing the instrument is essential for a thorough examination.

Proper training and experience are necessary for correct diagnosis. The diagnostic spectrum of colonoscopy encompasses not only macroscopic assessment of the condition of the mucosa, but also the possibility of collecting a targeted biopsy sample and, more recently, the use of dye spraying techniques and magnification (see Chapter 3). The instrument channel of the flexible endoscope allows for therapeutic treatment during the examination to an extent not possible with any other imaging technique. Polyps, for example, can be removed at first diagnosis and bleeding can be stopped immediately.

Thus, colonoscopy is a technically demanding examination procedure with a high clinical yield combined with the capability of therapeutic intervention.

Indications and Contraindications

Indications. An assessment of the condition of the colonic mucosa is important where there are clinical indications of colitis, i.e., abdominal pain, diarrhea, malabsorption, perianal bleeding as a result of possible intestinal ischemia, inflammation, erosions and ulcers of various geneses, polyps and tumors, diverticula, or vascular malformations. Changes in bowel habits and an increasing tendency toward constipation are cause for performing an endoscopic search for a stricture in the intestinal lumen, e.g., due to neoplasia, diverticular myochosis (thickening of the circular muscle layer), or postinflammation stricture (Tab. 1.1).

Thickening of the intestinal wall can be viewed using imaging techniques such as sonography (Fig. 1.1), computed tomography, and magnetic resonance imaging. A resulting pathological finding is an indication for colonoscopy that often can provide greater accuracy and allows taking a biopsy.

Early detection and cancer prevention. Colonoscopy is becoming increasingly important for early detection and the prevention of colorectal carcinoma in the asymptomatic general population. According to the guidelines established by the German Federal Committee of Doctors and Health Insurers (Bundesausschuss der Ärzte und Krankenkassen) on 5 October 2002 and based on recommendations recommendations from the German Society of Digestive and Metabolic Diseases (Deutsche Gesellschaft für Verdauungs- und Stoffwechselkrankheiten, DGVS), colonoscopy should be performed as a part of cancer prevention every 10 years among those aged 55 and over in the general population (14). Given the polyp–carcinoma relationship according to Vogelstein and the results of large cohort studies in the USA and Europe, there is no doubt about the effectiveness of endoscopic polyp removal in carcinoma prevention (17). With regard to these indications as well, total colonoscopy has proved itself over sigmoidoscopy and Hemoccult testing (11) (Tab. 1.2). Considering the current capacity for colonoscopy it would take 10 years to screen the US population following these guidelines (15).

Table 1.1 Indications for colonoscopyConstipationDiarrheaAbdominal painBleeding per rectum, unexplained anemia, weight lossPostpolypectomy surveillancePrevention/aftercare colorectal carcinomaPathological thickening of the colon wall detected by other imaging proceduresPrimary tumor search with metastasizing malignancy, if resulting therapeutic measures

Figure 1.1Thickened intestinal wall in the sigmoid colon. Ultrasound examination of the left lower abdomen.

Contraindications. Only in a limited number of situations do the risks of colonoscopy outweigh the benefits of its diagnostic value. Contraindications include suspected intestinal perforation, imminent risk of perforation accompanying acute diverticulitis, deep ulcerous lesions, or vascular necroses (Tab. 1.3).

The overall condition of the patient should always be assessed to determine whether he could tolerate the physical strain of preparing for colonoscopy and endoscopy, including conscious sedation. Colonoscopy in patients with a recentmyocardial infarction is associated with a higher rate of minor cardiovascular complications compared with control patients. (3)

Table 1.2 Recommendations for cancer prevention

Population

Periodic colonoscopy for cancer prevention

General population

Once every 10 years starting at age 55

Patients with colorectal polyp

Colonoscopy check-up once every three years, if no pathological findings at first examination, then further check-ups every five years

Patients with hamartomatosis polyposis

No general surveillance recommendations

Immediate family member with colorectal carcinoma or polyp at <60 years of age

Ten years earlier than the age of the index patient at which carcinoma/polyp occurred, repeat every 10 years

Immediate family member with colorectal carcinoma or polyp at >60 years of age

First colonoscopy at age 40, repeat every 10 years

Immediate family member with FAP (familial adenomatous polyposis)

Genetic carriers: starting at age 10, annual rectosigmoidoscopy, if polyp detection then colonoscopy; after proctocolectomy annual pouchoscopy

Noncarriers: same as general population

Immediate family member with HNPCC

Starting at age 25, annual colonoscopy

Patients with colitis ulcerosa

For pancolitis >8 years of age or left-sided colitis >15 years of age: complete colonoscopy with annual biopsy for two years, then once every two years

Patients with Crohn disease

No general recommendations at this time

Table 1.3 Contraindications for colonoscopy

Perforated intestine

Acute diverticulitis

Deep ulcerations

Severe ischemic necroses

Fulminant colitis

Cardiopulmonary decompensation

Attention

The physical stress of preparation for the examination and the colonoscopy itself limits its use in seriously ill patients.

Preparing for the Examination

Oral preparation. Thorough bowel cleansing is essential for a sufficient endoscopic examination of the colon. The development in 1990 of a nonabsorbable electrolyte solution (polyethylene glycol, PEG) by Fordtran was a significant improvement over earlier laxatives using sodium sulfate and modified forms are still in use today. But, due to the large quantity of liquid that must be consumed (up to 4 L) and the salty taste, these solutions are not tolerated by all patients. Their effectiveness has, however, been verified by numerous studies; data on sodium phosphate solutions (e.g., Fleet) and whether these are an improvement in terms of cleanliness and patient acceptability are less conclusive (8). Though they may appear to be a viable alternative for some patients, caution should be exercised if the patient has kidney insufficiency given the high phosphate content.

Enemas and clysmas. The use of an irrigator is recommended for patients who, due to an obstruction, cannot be prepared for examination using an oral solution. If the patient is admitted for emergency endoscopy, a quick cleansing using a clysma is a feasible option for partial colonoscopy.

Complications and Risks

Perforation, bleeding, and infection. Endoscopy of the colon entails risk of perforation, injury to blood vessels causing bleeding, and infection (Figs. 1.2, 1.3). The rate of complications can be minimized if the examiner takes precautions such as advancing the instrument only under conditions of high visibility. Sigmoidoscopy involves an average perforation rate of 1.8 per 100000 examinations; bleeding severe enough to require a blood transfusion and perforations requiring surgical repair occur at the same rate so that the number of patients who experience a serious complication is 6.4 per 100000 (10).

Comparing diagnostic and therapeutic colonoscopy (1, 4), statistics indicate that, with a total morbidity of 0.4%, more complications arise from therapeutic measures, such as poly-pectomies (1.2% vs. 0.2%) (Tab. 1.4).

Treatment. Not all complications require surgical intervention. Bleeding can be stopped in 92% of patients endoscopically and infections can be controlled with antibiotics. Injury to the serosa related to perforation of the intestine is painful for the patient and in most cases is surgically repaired before peritonitis occurs. In some patients, gaping wound edges can be closed with endoscopically applicable clips and further healed with a liquid diet and antibiotics (5).

Cardiopulmonary complications. The use of analgesics for colonoscopic examination increases the risk of cardiopulmonary complications, even when the utmost caution is exercised in selecting medication and dosage (cf. Chapter 4). Older and co-morbid patients are especially at risk for medicamentosus hypotension, tachycardia, and respiratory failure.

Fig. 1.2   Intestinal perforation

Fig. 1.3   Intestinal bleeding following an endoscopic polypectomy.

Fig. 1.4   Intestinal lumen with low air insufflation.

Fig. 1.5   Intestinal lumen with high air insufflation.

Table 1.4 Complications arising from colonoscopy (1,4)

Total morbidity

0.4%

for diagnostic colonoscopies

0.2%

for therapeutic colonoscopies

1.2%

Bleeding

0.2% of all colonoscopies

0.3–6.1% of therapeutic colonoscopies

Perforations

0.1% of diagnostic colonoscopies

0.1–0.3% of therapeutic colonoscopies

Mortality

0–0.006% of all colonoscopies

Attention

Cardiopulmonary complications are the leading cause of death related to colonoscopy.

General Principles

The success of the procedure is determined by the cooperation of the physician, assistant, and patient, all of whom must adjust to varying patient conditions in terms of anatomy and pain threshold, to the different equipment positions and functions, and to varying levels of training and expertise on the part of the examiner and assistants.

Insufflation of air. In order to inspect a 1.20-m-long, stool-filled hollow organ, it must be cleansed prior to the procedure and then distended using air during the examination. The distention of the intestinal lumen is vital for advancing the colonoscope under constant visualization, but it is also the source of much of the discomfort experienced by the patient through the mechanoreceptors and pain receptors. Using CO2 instead of air may be advantageous due to its quicker absorption. Nevertheless, a good rule of thumb for all colonoscopies: use as little air as possible and as much air as necessary (Figs. 1.4, 1.5).

Mesenteric discomfort. The patient may also experience discomfort from the mechanical strain on the mesentery. This occurs when the advancement of the colonoscope is prevented, for example, by looping in the sigmoid colon. An experienced examiner can determine the position of the instrument by the movement of the endoscope in the intestine and can attempt to avoid looping or to pull back (cf. Chapter 5) before the patient experiences noticeable discomfort.

Patient care. The examiner should continue to pay close attention to the patient while concentrating on the advancement of the colonoscope on the monitor screen. The effort to produce a thorough and accurate diagnosis is almost equally important to the patient as the subjective experience of colonoscopy, which includes all aspects of the examination, including the experience of discomfort, receiving sufficient information and the maintenance of dignity.

Five basic rules of colonoscopy

1. Do not advance the endoscope without a clear view of the lumen.

2. Do not advance the endoscope if there is any resistance.

3. When in doubt, pull back.

4. Use as little air as possible and as much air as necessary.

5. Pay attention to patient's pain reaction.

Anatomy of the Colon

The endoscopist views the colon from a perspective unlike that of any other visualizing technique, viewing the inner relief of the “intestinal skeleton,” which is made up of three straplike bands of longitudinal muscles (tenia coli) and numerous half-moon-shaped cross-folds (semilunar folds) which give rise to the pouchlike haustra between them (Fig. 1.6).

Structure of the intestinal wall. The intestinal wall can be divided microscopically into four layers, the structure of which does not vary significantly from the six macroscopic segments of the colon (rectum, sigmoid colon, descending colon, transverse colon, ascending colon, and cecum) (Figs. 1.7, 1.8). The endoscopic forceps biopsy usually takes samples limited to the mucosa. In order to collect deeper proportions of the intestinal wall (e.g., submucosa) it is practical to use a snare.

Colon segments. The division of the colon into segments is based primarily on anatomical rather than functional aspects. Only the rectum and cecum are unlike the other segments in that they function as reservoirs.

Cecum. Passage from the ileum to the cecum is restricted by the Bauhin valve that prevents the backward flow of the contents of the intestine out of the colon into the small intestine. The Bauhin valve is made up of two lips with a reinforced circular muscle layer that permit the opening of a narrow slit, the ileocecal valve, and that merge into two membrane folds at the front and back (Fig. 1.9).

The cecum is normally located intraperitoneally in the iliac fossa of the lower right abdomen. In the final months of pregnancy, the beginning of the large intestine grows up the inside of the right side of the abdomen. A “displaced” cecum can result if it remains at the level of the liver.

The three tenia of the cecum converge in a star shape at the end of the (vermiform) appendix that is not intubated during colonoscopy.

Fig. 1.6   Schematic structure of the colon wall. Tenia (1), pliquae semilunares (2), and haustra (3).

Fig. 1.7   Anatomy of the colon.

Fig. 1.8   Microscopic structure of the intestinal wall (with the kind permission of Prof. Dr. H. Arnholdt, Pathological Institute, Klinikum Augsburg).

(1)   Mucosa: deep, close together crypts with numerous goblet cells and enterocytes, high brush border;

(2)   Submucosa: loose connective tissue layer, latticelike formation of collagen fibers, blood, and lymph vessels, vegetative plexus submucosus;

(3)   Muscularis propria: strong inner circular muscle layer, outer longitudinal layer, reinforced tenia, plexus myentericus;

(4)   Serosa: peritoneal covering.

Fig. 1.9   Detailed view of the cecum and Bauhin valve.

Fig. 1.10   Rectum and anal canal.

Table 1.5 Mesenterial fixation of the colon

Intestinal segment

Mesentery

Meaning for endoscopy

Sigmoid colonTransverse colon

Persistent, mobile mesentery

Makes endoscope passage difficult due to mobility in abdominal cavity

Descending colon

Ascending colon

Cecum

Retroperitoneal fixation of the mesentery

Endoscopic passage easier

Rectum

Primarily retroperitoneal

Good maneuverability of the endoscope

Mesentery. The mesentery is a double layer of peritoneum, which, during the embryonic phase, attaches the ascending colon and the descending colon to the back wall of the abdomen, creating a retroperitoneal fixation; the mesentery persists as a free attachment for the transverse colon and sigmoid colon so that they remain mobile (Tab. 1.5). Because of this, the passage of the endoscope can result in colon movements and even looping in the abdominal cavity (see Chapter 5).

Rectum and anal canal. The 15-20-cm-long rectum is closed off to the outside by the hemorrhoidal zone, where the anal columns containing arterial and vascular bundles are located. Together with the reinforced muscle layers of the internal and external anal sphincter muscles, the hemorrhoidal zone supports bowel continence. The epidermis extends 2-3 cm into the anal canal. Cranially limited by a transverse fold (the Kohlrausch fold), the rectal ampulla is a highly expandable area that functions as a reservoir (Fig. 1.10).

Attention

Precise knowledge of anatomy is essential for the management of colonoscopy, correct description of pathological findings, and understanding the clinical features of intestinal diseases.

References

See Chapter 2.

2

Basic Examination Technique and Colonoscopy Workstation

G.Jechart

Learning Examination Technique

Learning colonoscopy technique requires motivation, manual dexterity, concentration, and patience on the part of the trainee. Already practiced in the technique of endoscopically examining the upper digestive tract, the beginner will learn about similarities and differences related to using a gastroscope vs. using a colonoscope.

Instrument Features

All endoscopes can be divided into three sections: the insertion tube, which is advanced in the patient, the instrument control head, where the physician can maneuver the endoscope tip and has access to the water/air supply and the instrument channel and, finally, the universal cord and plug, which connect the instrument to the supply unit (Fig. 2.1).

Insertion tube. The insertion tube of the video colonoscope consists of a ca. 130-cm-long tube containing optical fibers, digital wires, air and water nozzles, the instrument channel, and Bow-den cables for better mobility.

Located at the tip of the endoscope are the lens and video chip, which produces the image (Fig. 2.2).

The last 15 cm of the insertion tube are especially flexible and can bend in all four directions, allowing better maneuvering in the gastrointestinal tract. The degree of flexion of the colonoscope is 180° up/down and 160° to the right/left. Compared with the colonoscope, the gastroscope can be moved to a greater degree upward, but to a lesser degree in all other directions (Figs. 2.3, 2.4, Tab. 2.1).

Fig. 2.1   Main parts of the colonoscope. A Universal cord and plug, B Instrument control head, C Insertion tube (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.2   Tip of colonoscope (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.4   Comparing the outer diameters of the distal end of a colonoscope (left) and a gastroscope (right) (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.3   Maximum angling downward.

a   Colonoscope.

b   Gastroscope.

(Courtesy of Mr. Wirth, photo archive, Augsburg Clinic.)

Table 2.1 Comparing standard video endoscopes (example: Olympus)

Standard video endoscopes

Colonoscope

Gastroscope

Maximum angling

Up 180°

Up 210°

Down 180°

Down 90°

Right/left 160°

Right/left 100°

Outer diameter, distal end

12.8 mm

10.2 mm

Length of insertion tube

103 cm

103 cm

Angle

140°

130°

Fig. 2.5   Control head of a video colonoscope:

1   Function buttons, e.g., video recorder remote control

2   Freeze button

3   Suction button

4   Air/water button

5   Instrument channel

6   Locking device

7   Angling wheel (right/left)

8   Angling wheel (up/down)

(Courtesy of Mr. Wirth, photo archive, Augsburg Clinic.)

The sigmoidoscope measures only 60 cm in total length. Because of its high degree of maneuverability, it is sometimes used in patients where the indications for examination are limited to the sigmoid colon and rectum.

Different colonoscope models can vary in length, outer diameter, and width of the instrument channel.

Instrument control head. The functions necessary for maneuvering the tip the endoscope, for suction, cleansing, and air insufflation are all located on the control head. (Fig. 2.5).

The opening to the instrument channel is somewhat below the air/water cylinder, but before the air/water channel merges with the suction channel. The diameter of the inside of the instrument channel is between 2.8 mm and 3.7 mm, allowing the insertion of endoscopic accessories such as biopsy forceps or polypectomy snares (Fig. 2.6).

Video endoscopes also have remote control buttons that, according to model, may have various functions. These buttons can generally be used for freeze frames, video recording, printing, and adjusting illumination intensity (peak and average). Newer generations are equipped with so-called big chips that allow the projection of a high-resolution screen-size image onto a video monitor. The image can be digitally enhanced using modern image processing technology (e.g., Olympus CV-160) for structure enhancement, variable by several levels during and even after the examination (see Chapter 3).

Universal cord. The universal cord connects the endoscope to the light source, air supply, water supply, suction pump, and video processor. The video processor transmits the image to the monitor screen on the video tower (Figs. 2.7-2.10).

Operating the Endoscope

Before every examination, the suction, cleansing, and air insufflation functions on the endoscope must be checked and the “white balance” set on the video processor. The physician's left hand holds the control head of the endoscope while the right hand moves the insertion tube or controls fine adjustment of the outer angling wheel on the control head (Fig. 2.11).

Suction and cleansing. The index finger of the left hand can be used to depress the suction button while the middle finger can either press the air/water button lightly for insufflation or more firmly to activate the washing system (Fig. 2.12).

Fig. 2.6   Colonoscopy accessories (from left to right): biopsy forceps, clip applicator, injection needle, and polypectomy snare (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.7   Universal plug on an endoscope (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.8   Plugging the universal cord into the processing unit (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.9   Video processor (above) and light source (below) (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.10   Suction pump (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.11   Operating the instrument.

a   The examiner's right hand guides the tube or

b   Fine adjustment of the endoscope tip by moving the angling wheel.

(Courtesy of Mr. Wirth, photo archive, Augsburg Clinic.)

Fig. 2.12   Operating the valves.

a   Suction button.

b   Air/water channel.

(Courtesy of Mr. Wirth, photo archive, Augsburg Clinic.)

Flexion. Two wheels control the angling of the endoscope in different directions. Using the thumb of the left hand, the large wheel can be turned to move the tip of the endoscope up or down while the smaller wheel directs the tip of the endoscope right and left (Figs. 2.13, 2.14, Tab. 2.2). Each wheel has a locking device so that it can be fixed in one position, allowing, for example, the right hand to remain free to use the instrument channel (Fig. 2.15).

Advancing the endoscope. In an experienced and well-coordinated team, the assistant can advance the insertion tube in the colon while the physician uses both hands on the control head to steer the tip of the endoscope (Fig. 2.16). However, some examiners prefer to advance the shaft themselves in order to better feel the position of the instrument. In this case, the right hand is used only for fine adjustments using the angling wheels on the head of the endoscope (Fig. 2.17).

Fig. 2.13   Moving the large angling wheel.

a   Downward.

b   Upward.

(Courtesy of Mr. Wirth, photo archive, Augsburg Clinic.)

Fig. 2.14   Moving the endoscope tip corresponding to the maneuvering of the large angling wheel. a Upward (cf. Fig. 2.13a). b Downward (cf. Fig. 2.13b) (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.15   Inserting biopsy forceps into the instrument channel (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Table 2.2 Maneuvering the endoscope tip using the angling wheels

Rotation of the angling wheel

Movement of the endoscope tip

Large wheel: toward examiner

Raises the tip

Large wheel: away from examiner

Lowers the tip

Small wheel: toward examiner

Turns the tip to the left

Small wheel: away from examiner

Turns the tip to the right

Simulators

Maneuvering the endoscope and manual technique. The novice must first take time to study the functions of the endoscope. It is important to practice instrument handling before performing the first examination on a patient. The development of three-dimensional computer simulation can enable the trainee to practice maneuvering the endoscope and to develop the necessary manual dexterity (Figs. 2.18, 2.19).

According to one study evaluating usage of the Simbionix system, two hours of practice per day for three weeks are necessary in order for a novice to approach the level of handling expertise of an experienced endoscopist (6). Depending on the computer program, the virtual endoscopy simulator can simulate normal and pathological findings in the colon, helping to improve later detection of pathologies on actual patients.

Therapeutic interventions. Even though therapeutic interventions can now be computer simulated, experts agree that computer-simulation training of the novice endoscopist can offer only limited improvement in technique and skill; an actual examination situation is much more complex due to differences in mucosal properties and physiological factors. Thus, costly animal models are used in some courses aimed at maintaining endoscopic competency, with small groups practicing specific techniques (e.g., hemostasis) under more realistic conditions. The EASIE concept developed in Erlangen, Germany, is an animal-part simulator that integrates organs from a slaughterhouse into the model and, using perfusion, simulates in-vivo endoscopic interventions (7) (Fig. 2.20).

Fig. 2.16   The assistant advances the endoscope (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.17   The physician advances the endoscope (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.18   Simbionix computer simulator (courtesy of Simbionix).

Fig. 2.19   Virtual training (courtesy of Simbionix).

a   Manual skill training.

b   Virtual colonoscopy using a simulator.

Training on a Patient

Observation. Despite modern computer-assisted learning techniques, observing while an experienced endoscopist performs colonoscopy is a key part of training for the beginner. It is important that the explanation by the endoscopist is suited to the trainee's level of training and that the handling of the instrument in technically difficult situations is described. An expert description of pathological findings enables the student endoscopist to better identify pathologies already seen in textbooks.

Withdrawing and advancing the instrument. The first practical exercise to be performed on the patient is withdrawing the instrument from the cecum to the rectum, taking care that all segments are sufficiently visualized. The next objective is to learn how to advance the instrument to the cecum. For this step, the trainer advances the shaft while the student operates the control head. Only after advancement to the cecum can safely and successfully be performed should training begin for intubating the Bauhin valve (Tab. 2.3).

Simple and complex interventions. Simple interventions such as performing a forceps biopsy, removing small polyps, and performing hemostasis by injection should be mastered before performing colonoscopy without supervision, in order to spare the patient an unnecessary further examination.

Table 2.3 Steps in colonoscopy training on a patient

Steps

Objective of basic colonoscopy training

1

Observe examination procedure

2

Withdraw the instrument from the cecum to the rectum

3

Advance the instrument to the cecum under the guidance of an experienced endoscopist

4

Advance the instrument to the cecum under supervision, but without direct assistance

5

Intubation of the Bauhin valve

6

Interventions: forceps biopsy, removal of small polyps, simple hemostasis

Fig. 2.20   EASIE model for training in endoscopic interventions (courtesy of Dr. Maiss, University Clinic Erlangen).

More complicated maneuvers, such as the removal of larger or sessile polyps, the use of clip applications, dye spraying techniques, performing mucosectomies, balloon dilations, or bougienage, are only performed after acquiring sufficient experience in basic technique, e.g., during gastroenterological training. Training centers such as CCEPDT (Competence Centers in Education, Procedure Development, and Training), for example, offer quality-controlled courses taught by skilled endoscopists experienced in teaching (7).

The Colonoscopy Workstation

Layout and instrumentation in modern endoscopy units, where colonoscopy is performed under quality control, are designed according to normative standards, and also conduct regular hygiene checks.

Examination Room Set-up

The design of the colonoscopy workstation should meet not only the requirements of an ergonomic examination procedure and a patient-friendly atmosphere, but also must comply with regulations concerning ventilation and installation of electrical equipment. Keeping dust, micro-organisms and odors to a minimum is just as important for personnel as it is for the patient (Fig. 2.21).

Every examination room must have a hygienic area for hand washing. Direct access to a patient bathroom is also desirable.

The room where the preparations for endoscopy take place must be in the immediate vicinity of the examination room and must be able to be divided into clean and unclean zones.

Hygiene Standards for Reprocessing Equipment

Automated reprocessing. After use, the endoscope is wiped off in the examination room and placed in a container with a ten-side-based (e.g., Bodedex forte) cleansing solution where it is flushed. Aldehyde should not be used as it may cause protein fixations in the instrument channels. The endoscope is then disconnected from the power unit and brought to the storage area where it is again immersed in a cleansing solution and checked for leakages. A careful brush cleaning can reduce bacterial count by four log levels (Fig. 2.22). The valves should be removed and, together with the accessories, cleaned mechanically and enzymatically using an ultrasonic cleaner.

Fig. 2.21   Colonoscopy workstation. Examining table (1), Radiography equipment (2), Video tower (3), Power unit, endoscope with video processor (4), Light source (5), Air supply/pump (6), Suction pump (7), Instrument table for accessories (8) (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Reprocessing and disinfection procedures. Further cleaning of the endoscope can, in theory, be accomplished manually or automatically. However, automatic-washer disinfectors have distinct advantages with regard to protecting personnel from potential health hazards, as well for standardization of disinfection procedures (12).

The instrument and accessories are loaded separately into baskets or trays in the automatic-washer disinfector and the endoscope is attached to the automatic cleaning system (Fig. 2.23). A solution of either 2.4% glutaraldehyde or 10% succine dialdehyde is used for disinfection. The final rinse cycle is completed using sterilized water.

After thermochemical reprocessing and disinfection have been completed (ca. 40 minutes) the endoscope can be removed and allowed to dry. Air can be aspirated through all channels to speed up the drying process.

The endoscope is stored in a hanging position and without reattaching the valves to avoid recontamination resulting from residual dampness (Fig. 2.24).

Hygiene standards and tests. The majority of infections cited in the literature result from lacking hygiene, so it is vital that cleaning and disinfecting the instrument be conducted only by qualified personnel with up-to-date training (2). Hygiene standards exist for cleaning and disinfecting flexible endoscopes and accessories (13). Conducting quarterly tests as a quality control measure for equipment cleaning is recommended (9) (Fig. 2.24). This includes checking cleaning, disinfection, testing for microorganisms in all endoscope channels and lens washing systems. Detection of Escherichia coli or other enterobacteria or enterococci, in particular, is evidence of inadequate reprocessing. Correct endoscope reprocessing, disinfection and sterilization procedures are essential, and the health and safety of the patient, users and third parties must not be endangered.

Radiography Equipment Regulations

Radiographic screening is occasionally used to determine the position of the instrument in the patient. Commonly, a mobile radiograph is used, which is passed briefly over the patient's abdomen. The examination room must comply to specific standards, for example, must be large enough so that the axis of the radiographic path is at least 1.5 m from the nearest wall in order to avoid hazardous reflection of the ray.

Operating knowledge of radiography equipment (professional certification) is mandatory as is the wearing of appropriate protective clothing. A radiographic dosimeter must be worn on an appropriate position on the upper body, underneath the protective apron (Fig. 2.25).

Fig. 2.22   Brush cleaning the endoscope after use (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.23   Loading the endoscope in the automatic washer-disinfector (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.24   Quarterly hygiene tests are essential (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.25   Using radiography during colonoscopy (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

Fig. 2.26   Storing the endoscopes in lockers (courtesy of Mr. Wirth, photo archive, Augsburg Clinic).

References

1. American Society For Gastrointestinal Endoscopy. Complications of colonoscopy. Gastrointest Endosc 2003; 57:441–5.

2. Ayliffe G. Nosocomial infections associated with endoscopy. In: Mayhall G (ed.). Hospital Epidemiology and Infection Control. Philadelphia: Lippincott, Williams & Wilkins, 1999, pp. 881–95.

3. Cappell MS. Safety and efficacy of colonoscopy after myocardial infarction: an analysis of 100 study patients and 100 control patients at tertiary cardiac referral hospitals. Gastrointest. Endoscopy 2004;60:901–9.

4. Dafnis G, Ekbom A, Pahlmann L, Blomqvist P. Complications of diagnostic and therapeutic colonoscopy within a defined population in Sweden. Gastrointest Endosc 2001;54:302–9.

5. Farley DR, Bannon MP, Ziellow SP, Pauberlon JH, Illstrup DM, Larson DR. Management of colonoscopy perforations. Mayo Clin Proc 1997;72:729–33.

6. Ferlitsch A, Glauninger P, Gupper A et al. Evaluation of a virtual endoscopy simulator for training in gastrointestinal endoscopy. Endoscopy 2002;34:698–702.

7. Hochberger J, Maiss J, Hahn EG. The use of simulators for Training in GI Endoscopy. Endoscopy 2002;34:727–9.

8. Lazzaroni M, Bianchi Porro G. Preparation, Premedication and Surveillance. Endoscopy 2003;35:103–11.

9. Leiß O, Beilenhoff U, Bader L, Jung M, Exner M. Leitlinien zur Aufbereitung flexibler Endoskope und endoskopischen Zusatzinstrumentariums im internationalen Vergleich. Z Gastroen-terol 2002;40:531–42.

10. Levin TR, Conell C, Shapiro JA, Chazan SG, Nadel MR, Selby JV. Complications of screening flexible sigmoidoscopy. Gastroenterology 2002;123:1786–92.

11. Liebermann DA, Weiß DG, Bond JH, Ahnen DJ et al. Use of colonoscopy to screen asymptomatic adults for colorectal cancer. New Engl J Med 2000;343:162–8.

12. Rey JF et al. ESGE/ESGENA Technical note on cleaning and disinfection. Endoscopy 2003;35:869–877.

13. RKI-Empfehlungen „Anforderungen an die Hygiene bei der Aufbereitung flexibler Endoskope und endoskopischen Zusatzinstrumentariums„, Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz 2002;45:395–411.

14. Schmiegel W, Adler G, Fölsch U, Langer P, Pox C, Sauerbruch T. Kolorektale Karzinome, Prävention und Früherkennung in der asymptomatischen Bevölkerung – Vorsorge bei Risikogruppen. Dtsch Ärztebl 2000;97:1906–12.

15. Seeff LC et al. Is there endoscopy capacity to provide colorectal cancer screening to the unscreened population in the united states? Gastroenterology 2004;127:1661–1669.

16. Watanabe H, Narasaka T, Uezu T. Colonfiberoscopy. Stomach, Intestine 1971;6:1333–6.

17. Winawer SJ, Zauber AG, Ho MN, O'Brien MJ et al. Prevention of colorectal cancer by colonoscopic polypectomy. New Engl J Med 1993;329:1977–81.

3

Modern Endoscopic Techniques

M. Bittinger

The use of video endoscopes has led to a significant increase in the quality of visualization compared with examinations performed using fiberoptic instruments. The charged-coupled device (CCD) chips used in modern video endoscopes now provide such high resolution that it is possible to detect even tiny details on the mucosal surface, which has led to significant advancements in detecting small and flat lesions, especially flat polyps. Yet, increasing resolution using video chips is only one means of increasing diagnostic yield in endoscopic procedures. Other advancements made over recent years, which will be discussed here, are:

digital structural enhancement,

magnifying or zoom endoscopy,

chromoendoscopy,

fluorescence endoscopy.

Digital Structure Enhancement

The higher resolution of modern video chips is accompanied by improved processing of the video signal by the computer to which the endoscope is attached. When the signal is transmitted to the image on the monitor, image processing (digital structure enhancement) allows surface structure details to be emphasized (Fig. 3.1). Extremely high resolution of detail is possible, especially when used with magnifying endoscopy and chromoendoscopy as discussed below.

Magnifying or Zoom Endoscopy

Magnifying or zoom endoscopes enable image enlargement to a point nearly comparable to intravital microscopic examination of the mucosa.

Automatic and electronic magnification systems. Enlargement can be achieved using a built-in powered lens system, computer-supported electronic magnification to produce a digitally enlarged image, or a combination of the two. Electronic magnification is technically simpler from an instrument standpoint and does not require moveable parts, but the enlarged image often appears “grainy.” The degree of detail in electronic magnification depends on the resolution offered by the CCD chip used, which limits the degree of magnification attainable. Mechanical enlargement, which uses moveable lenses, has the advantage of optical zooming (as opposed to mere digital approximation), similar to that of a microscope, with current magnification ranging from 100-150-fold. It has the disadvantage, however, of having to be integrated into the endoscope in a moveable lens system, including motorization (either manually with a linkage system or using a built-in miniature servo motor).

Discriminating detail. Extreme enlargement allows a high level of discrimination of the selected image. Yet, to achieve a sharp picture, the endoscope tip must be fixed very close to the mucosal surface being examined (focal distance). To do so, transparent caps are placed on the endoscope tip and then set on the mucosa to keep it at the correct distance from the instrument. Large vessels in the area or respiratory movements may cause movement artifacts, rendering zoom endoscopy impossible in isolated cases.

Magnification can reveal surface structure detail of even the smallest vessels (Figs. 3.2, 3.3), especially when combined with surface staining techniques (chromoendoscopy, see below).

Fig. 3.1   Broadbased colonic adenoma.

a   View without digital structure enhancement.

b   View with digital structure enhancement. The surface structure can be seen more clearly.

Fig. 3.2   Detailed surface structure of a tubulovillous adenoma in the colon.

Fig. 3.3   Pathological vessels on the surface of a colonic carcinoma.

Chromoendoscopy

Chromoendoscopy is a simple method that can increase the therapeutic yield of endoscopy, in particular, with regard to diagnosing dysplasia and detecting and treating flat neoplasias in the colon. Dye spraying helps distinguish fine surface details on the mucosa, allowing, on the one hand, better detection and classification of otherwise easily missed flat polypoid lesions, while, on the other hand, making it easier to distinguish between the polyp and the surrounding mucosa.

Dyes. Either absorptive or contrast dyes can be used. Contrast dyes are not absorbed by the mucosa but instead collect in tiny grooves on the mucosal surface, emphasizing surface detail. Absorptive dyes, unlike contrast dyes, are actively absorbed by the mucosa. Their use thus is also referred to as intravital staining. The dye is absorbed differently by dysplastic or malignant tissue than by healthy tissue, giving rise to differences in staining pattern, which allow for better differentiation between healthy and diseased tissue.

Examinations of the colon use mostly contrast dyes; indigo carmine is the most frequently used. Absorptive dyes (methylene blue, crystal violet) are used more often in the upper gastrointestinal tract (especially in the esophagus), though they can also be used in the colon. Contrast dyes are much easier to use than absorptive dyes as they can be sprayed using a dye-spraying tube without specially preparing the surface and there is no waiting time for absorption by the mucosa. The extra time required for staining using indigo carmine is minimal and the resulting gain in visual information impressive.

Table 3.1 provides an overview of the three most commonly used dyes and related techniques for their use.

Pit pattern classification. Combining zoom endoscopy with surface staining enables differentiation of the mucosal surface comparable to that achieved using a microscope. This technique forms the basis of pit pattern classification of surface structures of polypoid colonic lesions, which was introduced by Kudo in 1996. The pit pattern classification is useful for further distinguishing between nonneoplastic (hyperplastic or inflammatory) and neoplastic (adenomatous or malignant) lesions. Modern high-resolution video endoscopes are generally sufficient for pit pattern classification, even without using special magnification techniques.

The pit pattern classification divides the tiny pits on the surface of polypoid lesions by size and form into five groups (pit patterns I-V). Group III is further subdivided into two subgroups (Type IIIS [S for small] and Type IIIL [L for large]). 3.1 gives an overview of the classification system and corresponding characteristics. With a little practice, correct classification is straightforward and reproducible.

Type I and Type II findings correspond to nonneoplastic lesions, Types III-V are nearly always neoplastic lesions, whereby Type V lesions are highly suspicious for the presence of malignancy. Systematic studies have shown that pit pattern classification has a sensitivity of 92-98% and a specificity of 61 -95% for distinguishing between neoplastic and nonneoplastic lesions. Thus, its routine clinical use is worthwhile.

Fluorescence Endoscopy

Fluorescence endoscopy is a new procedure that increases endoscopic detection of poorly visible malignancies or premalignancies. Fluorescence can be endogenous or exogenous and is commonly induced using 5-aminolevulinic acid.

Exogenously induced fluorescence. Special sensitizers are administered exogenously (locally or systemically as an oral solution) and accumulate selectively in malignant tissue. Exposure to light of a certain wavelength then induces selective (red) fluorescence.

   3.1 Overview and examples of pit pattern classification

Pit pattern type and characteristics

I   round pits

II   stellar or papillary pits

III S   small tubular or round pits

III L   large tubular or round pits

IV   gyruslike or branchlike pits

V   nonstructural pits

Fig. 3.4   Patient with ulcerative colitis.

a   Conventional white light endoscopic image with clear vascular structure.

b   Using blue light one sees selective red fluorescence of a small mucosal area corresponding to the histological “flat adenoma” with dysplasia. The patient was sensitized with 20 mg/kg 5-aminolevulinic acid five hours beforehand.

Exogenously induced fluorescence following sensitization with 5-aminolevulinic acid is currently most widely used in urology. Preliminary use of this method in gastroenterology has given hope that it may lead to the development of improved early detection of carcinomas and dysplasias related to Barrett esophagus, ulcerative colitis, and other premalignant tissues. Figure 3.4a shows an apparently nonpathological colon from a patient who has had ulcerative colitis for several years. Figure 3.4b shows a selective red fluorescence of a “flat adenoma” in the same patient.

Autofluorescence. The use of autofluorescence has been most extensively studied in pulmonology research. Endogenous fluorophores (such as collagen, elastin, FAD, NADH) can be found in various concentrations and states of oxidation in malignant and nonmalignant tissue, allowing tissues to be distinguished based on their different autofluorescence. This ultimately leads to reduced green autofluorescence, so that pathologies appear red or brown.

Disadvantages. Significant disadvantages of the method are that glass-fiber endoscopes have to be used and that the administration of 5-aminolevulinic acid for exogenous fluorescence induces light sensitivity in the patient.

Prototypes of new video endoscopes are currently being evaluated, as is the use of new locally administered sensitizers that do not result in light sensitivity.

References

1. Kato S, Fujii T, Koba I et al. Assessment of colorectal lesions using magnifying colonoscopy and mucosal dye spraying: Can significant lesions be distinguished? Endoscopy 2001;33:306–10.

2. Kiesslich R, Jung M. Magnification endoscopy: Does it improve mucosal surface analysis for the diagnosis of gastrointestinal neoplasia? Endoscopy 2002;34:819–22.

3. Kudo S, Tamura S, Nakajima T, Yamano H, Kusaka H, Watanabe H. Diagnosis of colorectal tumorous lesions by magnifying endoscopy. Gastrointest Endosc 1996;44:8–14.

4. Messmann H. Fluoreszenzendoskopie in der Gastroenterologie. Z Gastroenterol 2000;38:21–30.

5. Messmann H, Endlicher E, Freunek G, Rümmele P, Schölmerich J, Knüchel R. Fluorescence endoscopy for the detection of low and high grade dysplasia in ulcerative colitis using systemic or local 5-aminolaevulinic acid sensitisation. Gut 2003;52:1003–7.

6. Tung S, Wu C, Su M. Magnifying colonoscopy in differentiating neo-plastic from nonneoplastic colorectal lesions. Am J Gastroenterol 2001;96:2628–32.

IINormal Examination Procedure and Non-pathological Findings

4 Before the Examination

5 Inserting the Endoscope and Advancing It in the Colon

6 Normal Appearance of the Intestinal Segments

7 Normal Postoperative Appearances

4

Before the Examination

A. Probst

Informing the Patient

The decision if colonoscopy is the best diagnostic or therapeutic approach should be made based on present indications (see also Chapter 1). If the indication supports the need for colonoscopy, the patient must be informed prior to examination about the necessity, procedure, and possible complications of the examination and he must sign a consent form.

Serious complications are rare and the vast majority are due to cardiopulmonary complications. Risk varies greatly from one individual to the next, depending on cardiopulmonary disease status and the use of an analgesic. In addition to more general risks, there are also potential complications specifically related to colonoscopy (foremost bleeding and perforation; see also Chapter 1). In any discussion preceding colonoscopy, the patient must also be informed of the possibility of polypectomy, which entails increased risk.

For outpatient examinations, the patient must be cautioned against performing any activities that could cause harm to him or others for a period of 24 hours following sedation (e.g., driving, operating heavy or complex machinery, signing important documents such as contracts). Alternative examination and therapeutic options should also be mentioned. Standardized written consent forms may make discussion and documentation easier, but they cannot replace an informative discussion. The patient must be given sufficient time between discussion and the actual examination to consider his decision; according to German law, the examination can be performed no sooner than one day after the discussion between patient and physician (7).

Sedation and Medication

Sedation and Analgesics

Colonoscopy can theoretically be performed without sedation, and there are no fixed rules for premedication. Nonetheless, premedication improves examination conditions for both patient and physician. This has been confirmed by results from a study by Terruzzi et al. comparing routine premedication prior to colonoscopy to “on-demand” sedation during the examination. Among patients who began the procedure without sedation, 66% requested an analgesic during the examination and a larger number of them also refused to undergo another colonoscopy in the future (22% vs. 10% in the comparison group) (10).

Benzodiazepines.