Miss rate for colorectal neoplastic polyps:: a prospective multicenter study of back-to-back video colonoscopies

Background and study aim: Polyp miss rates during colonoscopy have been calculated in a few tandem or back-to-back colonoscopy studies. Our objective was to assess the adenoma miss rate while limiting technique or operator expertise biases, i.e. by performing a large multicenter study, with same-day back-to-back video colonoscopy, done by two different operators in randomized order and blinded to the other examination. Patients and methods: 294 patients at 11 centers were included. Among the 286 analyzable tandem colonoscopies, miss rates were calculated in both a lesion- and patient-based analysis. Each of these rates was determined for polyps overall, for adenomas, and then for lesions larger than 5 mm, and for advanced adenomas. Univariate and logistic regression analysis were performed to define independent variables associated with missed polyps or adenomas. Results: The miss rates for polyps, adenomas, polyps ! 5 mm, adenomas >= 5 mm, and advanced adenomas were, respectively, 28 %, 20 %,12 %, 9 % and 11 %. None of the masses with a carcinomatous (n = 3) or carcinoid component (n =1) was missed. The specific lesion miss rates for patients with polyps and adenomas were respectively 36% and 26% but the corresponding rates were 23% and 9.4% when calculated for all 286 patients. The diameter (1-mm increments) and number of polyps (>= 3) were independently associated with a lower polyp miss rate, whereas sessile or flat shape and left location were significantly associated with a higher miss rate. Adequacy of cleansing, presence of diverticula, and duration of withdrawal for the first procedure were not associated with adenoma miss rate. Conclusions: We confirm a significant miss rate for polyps or adenoma during colonoscopy. Detection of flat polyps is an issue that must be focused on to improve the quality of colonoscopy.