The aim of this study is to evaluate FUSE-colonoscopy in terms of feasibility and its possible additive contribution in the detection of important lesions, namely polyps and cancers, compared to the standard "forward-viewing" approach, with and without the addition of the right-colon retroflexion technique, in a series of patients undergoing back-to-back screening or surveillance colonoscopies in a randomized fashion.

We changed the anticipated number of subjects enrollment for study: NCT02117674 from 120 to 200 based on the following sample size estimation:

Tandem colonoscopies studies results, show that novel endoscopic technologies detect about 20% more adenomas than those conventional colonoscopy does (missed adenomas). Since FUSE colonoscopy cannot be considered as a perfect examination, we hypothesize that conventional colonoscopy will detect one third of the missed adenomas that FUSE detects in a similar setting. Therefore a sample size of 120 adenomas achieves 80% power to detect an odds ratio of 3.0 using a two-sided McNemar test with a significance level of 0.05. The odds ratio is equivalent to a difference between two paired proportions of 14% which occurs when the proportion of detected missed adenomas during FUSE is 21% and the proportion of missed adenomas during conventional colonoscopy is 7%. During one year period before the study initiation, our colonoscopy performance quality data show that we detect a mean number of adenomas per patient equal of 0.7 in a population similar to the one recruited in our study. Therefore, 172 patients overall will be required to detect 120 adenomas. Given the uncertainty of our estimation and in order to cope with patients exclusions, withdrawals and unexpected incomplete colonoscopies, we decided to recruit 200 patients.

A more extensive description regarding the investigators study is provided in the following fields.

Inclusion Criteria:

• adults undergoing elective screening or surveillance colonoscopy
• symptomatic adults with indication for colonoscopy

Exclusion Criteria:

• age over 80 years
• poor overall health (ASA III, IV)
• recent abdominal surgery
• presence of abdominal wall hernias
• active colitis
• multiple right colon diverticula
• previous bowel resection
• inflammatory bowel disease
• polyposis syndromes