Abstract and Introduction
Abstract
Some patients who undergo colonoscopy that appeared to have cleared the colorectum of neoplasia return within a short interval (1-3 yr) with colorectal cancer. Although several a priori mechanisms could account for this occurrence, wide variation in detection rates of adenomas and cancer at colonoscopy suggests that suboptimal colonoscopic technique is a significant contributor. Optimal technique with white-light colonoscopy involves taking adequate time for inspection during withdrawal (an average of at least 6 min in normal colons), interrogating the proximal sides of folds, flexures, and valves, clearing fluid and debris, and distending adequately. Some adjunctive techniques are directed toward exposing more colonic mucosa during colonoscopy. Wide-angle colonoscopy appears to improve efficiency but does not eliminate miss rates. Colonoscopy in retroflexion was unsuccessful in reducing miss rates in one study, whereas cap-fitted colonoscopy was successful in reducing miss rates in one small study. Techniques to improve detection of flat lesions include pancolonic chromoendoscopy (CE). In two randomized controlled trials, CE improved adenoma detection, but CE does not appear to provide substantially greater yields than those obtained by the more sensitive white-light colonoscopists. Narrow band imaging and autofluorescence are being assessed for improved detection of flat lesions. Adenoma detection rates are an important measure of the quality of colonoscopy and should be reported to endoscopists in quality improvement programs in colonoscopy.
Introduction
The importance of maximizing detection of neoplasia during colonoscopy is obvious from a patient's perspective. Patients who submit themselves to screening and surveillance colonoscopy do so with the hope and expectation of preventing their own development of and death from colorectal cancer. It is the obligation of colonoscopists to satisfy their hope and expectation to the highest degree possible. The presentation of a patient with colorectal cancer, and particularly fatal colorectal cancer, within one to a few years of a colonoscopy that purportedly cleared the colon of neoplasia is devastating for the patient and the endoscopist. Further, this occurrence may result in medical-legal action against the physician, claiming that the technical performance of the examination was negligent.
Based on the studies of incident colorectal cancer rates after clearing colonoscopy, colonoscopy and polypectomy have been estimated to prevent approximately 80% of colorectal cancers; however, some recent studies have challenged this notion, and one analysis even failed to demonstrate protection of colonoscopy and polypectomy against interval cancers.
The purpose of this review is to summarize current evidence on failed detection by colonoscopy and to review available evidence on what constitutes optimal examination technique for neoplasia during colonoscopy. Because detection of neoplasia is the fundamental goal of most colonoscopic examinations, and given that the technique has been used in clinical practice for 40 yr, with recent estimates of up to 15 million colonoscopies per year performed in the United States, it would seem that optimal withdrawal technique would have already been elucidated in detail. However, examination technique has been largely ignored in colonoscopy teaching. Older textbooks of colonoscopy place much more emphasis on colonoscopic insertion technique and technical aspects of polypectomy, whereas withdrawal technique is only discussed briefly.
This review will summarize the available evidence regarding what constitutes optimal withdrawal technique and suggest specific important questions regarding withdrawal technique that could be answered by additional investigation.