Background and goals: Missed adenomas are likely to be located in the proximal colon and failure to detect these lesions might explain the occurrence of a certain percentage of interval carcinomas. Though studies have demonstrated increased detection of significant neoplastic lesions in colonoscopic examinations where the withdrawal time is 6 min or more, there are no recommendations on how much time to spend in each colonic segment. The aim of the trial was to find ways to reduce the number of lesions missed in the proximal segments of the colon assessing the difference in adenoma detection rate (ADR) between two colonoscopic withdrawal timed techniques.
Study: This was a randomized trial in a university hospital. Population was composed of patients referred for screening colonoscopy. The Main Outcome measurements was ADRs for patients subjected to a timed colonoscopy with specific withdrawal times, with special interest in the proximal colon, and implying a minimum of 2-min withdrawal delay in the cecum and right colon, a 1-min delay time in the transverse colon, and a minimum additional 3-min delay time in the left colon, as compared to a standard timed colonoscopy with free withdrawal delay time of at least 6 min.
Results: A total of 1160 patients were included. Eleven were initially excluded due to incomplete colonoscopies. Of the remaining 1149 patients, 573 were randomized to the group with fixed withdrawal times (Group A) and 576 to conventional withdrawal (Group B). Median age was 57 years (SD 6), a total of 634 (55.2%) were male patients and the mean withdrawal time was 7:05 min (SD 1 min). Seven hundred and eighty-one adenomas/serrated lesions were found in 470 patients (1.66 per patient), with 28 advanced lesions and 3 adenocarcinomas. Global ADR was 41% with no significant statistical differences between the two groups (42.1% vs 39.8%, p 0.43), respectively. A multivariate analysis showed clear relation between the finding of adenomas and higher BBPS ratings (Adjusted Odds Ratio [aOR] 0.92, p 0.05), age (aOR 1.03, p 0.01), male sex (aOR 1.51, p 0.001), and time of withdrawal (aOR 1.17, p 0.001), while no association was observed with either withdrawal technique (aOR 0.89, IC 95% 0.70-1.03, p 0.32). There was no statistical significant difference between the two groups concerning the finding of proximal lesions (cOR 0.93, CI 95% 0.71-1.20, p 0.56) (aOR 0.89, CI 95% 0.69-1.17, p 0.41) or serrated polyps (cOR 0.81, CI 95% 0.51-1.27, p 0.35) (aOR 0.81, IC 95% 0.51-1.28, p 0.36).
Conclusions: Fixed withdrawal times did not prove to lead to an increase in the number of detected adenomas. Nevertheless, our study supports previous reports stating that longer withdrawal times are indeed associated with better proximal and distal adenoma detection.
Keywords: Adenoma detection rate; Colorectal cancer screening; Quality in colonoscopy; Serrated polyps.