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Colonoscopy Withdrawal Time Predicts Adenoma Detection Rates

Findings from a large single-center study support withdrawal times of at least 7 minutes.

According to current recommendations from the U.S. Multi-Society Task Force and a joint task force of the American College of Gastroenterology and the American Society for Gastrointestinal Endoscopy, endoscopists should record their rates of adenoma detection during colonoscopy. Those who have suboptimal rates (<25% in men [age, 50] and <15% in women [age, 50]) should measure their withdrawal times, with the goal being an average of at least 6 minutes. The evidence base for these recommendations is limited.

In this study, researchers evaluated the correlation between individual endoscopists’ average withdrawal times during negative colonoscopy and their overall polyp detection rates. Data were reviewed for 43 endoscopists who performed a total of 10,995 routine colonoscopies at a single center during 2003. Each endoscopist had performed at least 50 negative colonoscopies during the year. Withdrawal times were measured only in individuals with intact colons and with normal examinations (i.e., no polyps detected or therapy performed). Histologic data were not available; polyp size was estimated by the endoscopists (range, 1–5 mm, 6–9 mm, 10–19 mm, and 20 mm).

The endoscopists’ average withdrawal times for normal procedures varied from 4.2 minutes to 11.9 minutes (median, 6.3 minutes). Their polyp detection rates ranged from 23.6% to 65.6% (median, 42.7%). The median polyp detection rate corresponded to a withdrawal time of 6.7 minutes, and a strong correlation existed between polyp detection rates and mean withdrawal times (r=0.76; P<0.0001). Polyp detection rates in the 25th percentile correlated with a mean withdrawal time of 5.1 minutes, and those in the 75th percentile correlated with a mean withdrawal time of 8.8 minutes.

Longer experience of endoscopists was correlated with lower polyp detection rates (P=0.009), a finding driven mainly by the detection of smaller polyps (5 mm); as polyp size increased, the inverse association between detection rate and experience diminished. Associations between withdrawal time and detection of larger polyps, including 6- to 9-mm polyps, were not significant, although endoscopists’ rates did vary substantially for detecting larger polyps. The authors concluded that a withdrawal time of at least 7 minutes resulted in detection rates above the 50th percentile for polyps of all sizes.

Comment: These results provide important validation for the concept of longer withdrawal times during colonoscopy. This concept is receiving increased attention because of the recent recognition that colonoscopy provides considerably less protective value against the development of cancers than was previously thought. Endoscopists are encouraged to prioritize measurement of adenoma detection rates in continuous quality improvement programs. For individuals with low detection rates, withdrawal time is the easiest endpoint to measure and correct.

— Douglas K. Rex, MD

Published in Journal Watch Gastroenterology December 15, 2006

Citation(s):

Simmons DT et al. Impact of endoscopist withdrawal speed on polyp yield: Implications for optimal colonoscopy withdrawal time. Aliment Pharmacol Ther 2006 Sep 15; 24:965-71.

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