Effect of 6-Minute Colonoscopy Withdrawal Time Policy on Polyp Detection Rate in a Community Hospital

In 2002, a U.S. Multi-Society Task Force on colorectal cancer recommended a 6-minute or more withdrawal time as an indicator of a quality colonoscopy. In 2006, Barclay, Vicari, Daughty, Johanson, and Greenlaw (2006) found a correlation between longer withdrawal time and an increased rate in the detection of adenomas. In January 2008, the endoscopy department at our institution adopted the Multi-Society Task Force recommendation. The aim of our study was to evaluate the effect of a minimal 6-minute withdrawal time policy at our institution on polyp detection rate. All colonoscopies performed for screening indications from April 2007 to September 2008 were reviewed retrospectively. Group I (pre-policy) was compared with Group II (post-policy). Data collected included age, gender, indication, polyp detection rate, size, and withdrawal time. Unpaired t tests evaluated pre- and postprocedure results. Fisher's exact tests were used to compare detection rates between withdrawal time less than 6 minutes and more than 6 minutes. Mann-Whitney U Tests were performed to analyze the significance between the number of polyps detected for withdrawal time less than 6 minutes versus more than 6 minutes. A total of 1,342 colonoscopies were available for analysis in Group I and 1,316 in Group II. Polyp detection rate was 46.6% in Group I versus 48.2% in Group II (rho = .39), a non-statistically significant difference; however, there was a trend toward identifying small-and medium-sized polyps in Group II. Small polyps can carry a risk of severe dysplasia (Church, 2004). Data were then analyzed for withdrawal time. The polyp detection rate was 20.9 in procedures that took less than 6 minutes versus 48.3 in those that took more than 6 minutes (p <= .01). In this study, a 6-minute or more withdrawal time increased the polyp detection rate by 133% for all polyp sizes, especially small and medium. Small polyps (5 mm or less) should be removed and not ignored. A 6-minute or more withdrawal time should be mandatory in those patients without a previous colon resection.