Colonoscopic Withdrawal Times and Adenoma Detection during Screening Colonoscopy
By Malcolm Robinson, MD, FACP, FACG, Emeritus Clinical Professor of Medicine, University of Oklahoma College of Medicine, Oklahoma City. Dr. Robinson reports no financial relationship to this field of study.
Synopsis: In the setting of screening colonoscopy, longer durations of observation during withdrawal of the colonoscope were associated with higher detection rates for neoplasia.
Source: Robert L Barclay, et al. The New England Journal of Medicine. 2007;355:2533-2541.
Colonoscopy is widely employed as the preferred screening modality for detection of colon neoplasia. This is based on the belief that excision of early neoplastic lesions will dramatically reduce subsequent development of adenocarcinoma of the colon. The potential reduction in colorectal cancer may be as high as 90% as a result of colonoscopy and polypectomy. In the study being reviewed, 12 highly experienced gastroenterologists performed 7882 colonoscopy examinations over 15 months. Of these, 2053 were screening exams in patients who had not previously undergone colonoscopy. Sizes, histology, and numbers of neoplastic lesions were recorded from these latter individuals. Also recorded were durations of colonoscope insertion to the cecum and withdrawal to the anus as recorded for each exam done by each of the participating gastroenterologists. Neoplastic lesions were found in 25.3% of screened subjects. Large differences were noted in the detection rates among these individual gastroenterologists, ranging from 0.10 to 1.05 mean lesions per subject screened. Likewise, percentages of subjects found to have adenomas differed between examiners, from a low of 9.4% to a high detection level of 32.7%. Mean colonoscope withdrawal times from the cecum to the anus also varied among these gastroenterologists, from 3.1 to 16.8 minutes. Statistical analysis of the results indicated that colonoscopists spending more than 6 minutes for scope withdrawal had significantly higher detection rates for any neoplasia vs those with withdrawal times less than 6 minutes (28.3% vs 11.8%, p < 0.001). Results for advanced neoplasia (ie, villous features, dysplasia, or cancer) diverged in a similar pattern (6.4% vs 2.6%, p < 0.005). Incidentally, the range for detection of hyperplastic (non-neoplastic) polyps also varied between gastroenterologists (5.5-28.6%). The authors of this study cautiously suggest that the high correlation between slower withdrawal of the colon endoscope and higher detection rates for neoplasia might mean that standards for maximally effective colonoscopy could reasonably include a minimum time for colonoscope withdrawal.
Commentary
In an accompanying editorial (NEJM 355:2588-2589), David Lieberman reiterates evidence that supports reduced colon cancer rates over a period of 10 years in patients with previous normal colonoscopies. However, he stresses the point that colonoscopy can only be a truly successful screening tool if there is a low rate of complications along with few missed lesions. Dr. Lieberman also comments that the results of the Barclay study should be intuitive in that careful and unhurried examination of the colon ought to achieve maximal patient benefits. There are cancers (0.3 to 0.9%) that occur in patients who have ostensibly had previous normal colonoscopy examinations. Possible explanations include somewhat less likely carcinogenesis without previous benign neoplasia or extremely rapidly growing lesions. However, missed lesions at colonoscopy are by far the most likely cause for cancer seen in individuals with reportedly normal recently performed colonoscopies. Perhaps more than ever before, we live in an age that seems unusually strongly influenced by monetary issues. Many gastroenterologists feel that they are under pressure to perform as many procedures as possible to maximize reimbursement despite perceived decreases in procedure-related fees. Some endoscopists feel that available slots for performing procedures are limited, and this also leads to hurry. Indeed, in the Barclay study under discussion, so-called "standard" 30-minute slots were used for these procedures. It seems to this reviewer that there should be strong incentives not to rush procedures. It is far more than intuitive that slow and careful observation during all phases of colonoscopy will achieve the best results for the patients being examined. For some patients, times much greater than 6 minutes will be required, and a 30-minute slot may be painfully inadequate. It seems unlikely that a truly excellent colon endoscopy can ever be done with rushed insertion or withdrawal of the colonoscope. The authors of this study have recommended additional prospective studies to confirm their work. I would argue that gastroenterologists should heed the existing results…and slow down.
In the setting of screening colonoscopy, longer durations of observation during withdrawal of the colonoscope were associated with higher detection rates for neoplasia.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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