Retrospective analysis of missed advanced adenomas on surveillance colonoscopy

Miss rates of large polyp/cancer during colonoscopy are reported from tertiary centers where experts do the colonoscopies. This information is important for determining surveillance intervals for repeat colonoscopy, patient safety, and malpractice issues. We evaluated retrospectively the miss rates of advanced adenomas in the setting of a GI fellowship training where most colonoscopies are done by closely supervised fellows.

We reviewed the 235 patients who had at least one repeat colonoscopy after initial polypectomy, between 1992 and 1999, at the Dayton Veterans Affairs Medical Center. Advanced adenomas were defined as polyps 10 mm or greater in size with or without a villous component or high-grade dysplasia. Data of missed advanced adenomas on 122 patients who had complete colonoscopy with satisfactory preparation and the excluded patients are reported.

Four advanced adenomas (one had intramucosal cancer) on second colonoscopy and two advanced adenomas on third colonoscopy were missed. The miss rate of advanced adenoma for 232 patients was 1.7%, and the miss rate for the 122 patients with complete colonoscopy and satisfactory colon preparation was 2.5% and 3.3% on second and third repeat colonoscopy, respectively. No cancer was missed.

The present study shows an advanced polyp miss rate that is comparable with other studies even in a fellowship training setting. Prospective studies with tandem surveillance colonoscopy are needed to confirm our findings.