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

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.

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.

The miss rates for polyps, adenomas, polyps > or = 5 mm, adenomas > or = 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 (> or = 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.

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.