Longer Right Colon Withdrawal Time and Retroflexion Duration Significantly Increases Adenoma Detection Rate: A Randomized Controlled Trial at Three Endoscopy Centers

Abstract

Purpose Detection of adenomas is the foundation of colorectal cancer screening utilizing screening colonoscopies. Adenoma detection rate (ADR) is an increasingly utilized core quality measure for colonoscopies. Colonoscopy is an effective tool to prevent colon cancer but missed lesions can lead to development of interval colon cancer. These missed lesions are particularly in right-side of the colon. Careful examination of the right colon is recommended but the ideal withdrawal time for the right colon is unknown. Design /Method We conducted a prospective, randomized controlled trial in patients undergoing screening or surveillance colonoscopies for colorectal cancer at three hospitals. Adenoma detection rate was defined as the proportion of colonoscopies in which adenomas were detected, compared to all colonoscopies. ADR was compared in patients with < 3mins right colon (up to hepatic flexure) withdrawal time, to patients with ≥ 3mins right colon withdrawal time. Time spent from identifying the appendiceal orifice till the start of withdrawal, which included time spent intubating the terminal ileum and examining the ileum, was excluded as this time is usually not used to identify polyps. A secondary end point was to observe if retroflexion for ≥ 30 seconds compared to < 30 seconds improved ADR in the right colon. Results A total of 250 patients after randomization were included in the analysis. This sample included 135 patients in the < 3 minute right colon withdrawal group (RCWG) and 115 patients included in the ≥3 minute RCWG. Adenoma detection rate in the right colon was 33% if the right colon withdrawal time was ≥3mins compared to 14% if it was < 3 mins; the likelihood of finding right-sided adenomas was 3 times greater in the ≥ 3 min group compared to the < 3 min group, (OR 3, p<0.001, 95% CI 1.62-5.64). The adenoma detection rate in the right colon was also significantly higher when the modified right colon withdrawal time was used in ≥ 3mins group vs. < 3mins group which also showed that the ≥ 3mins group was 3 times more likely to find adenomas in the right colon compared to the < 3 min group (OR 3, p<0.001, 95% CI 1.62-5.64).Adenoma detection rate in the right colon was 45% when retroflexion was performed for≥ 30 seconds compared to 23% in the group where it was performed for < 30 seconds (OR 2.8, p=0.01, 95% CI 1.26 – 6.0). Polyps that were seen only on retroflexion, which could not be seen on forward view, were significantly more likely to be found in the ≥ 30 second group (22%, n =8) compared to the < 30 second group 3%, p<0.001. Conclusion Adenoma detection rate in the right colon was significantly higher when three minutes or more were spent examining the right colon during withdrawal. Significantly higher rates were seen even after taking polypectomy into account and in the average risk screening population. Adenoma detection rate in the right colon was also significantly improved when retroflexion wasperformed for more than 30 seconds.