Impact of the Second Examination of the Proximal Colon on the Adenoma Detection Rate: A Prospective Randomized Controlled Trial

Interval colorectal cancer identified before the next surveillance colonoscopy was more likely to be located in the proximal colon. This study aimed to determine whether a second examination of the proximal colon could increase the adenoma detection rate (ADR). METHODS: Patients undergoing colonoscopy for any indications were recruited for the study. After the colonoscopy was completed with the first standard forward view examination of the proximal colon, patients were randomized to either the intervention group, in which the proximal colon was once again inspected, or the control group, in which the proximal colon was inspected once. The primary outcome was the proximal colon ADR. RESULTS: A total of 840 patients were enrolled for intention-to-treat analysis (intervention group, n = 420; control group, n = 420). The proximal colon ADR in the intervention group was significantly higher than that in the control group (35.7% vs 25.2%, P = 0.001). The whole-colon ADR was also higher in the intervention group than in the control group (44.0% vs 34.0%, P = 0.003). The higher ADR in the intervention group was also confirmed by the per-protocol analysis. Older age, adenoma detected on the first proximal colon examination, and longer total proximal colon withdrawal time were independent factors for detecting ≥1 adenoma on the second withdrawal from the proximal colon. DISCUSSION: The second examination of the proximal colon significantly increased the proximal colon ADR and whole-colon ADR in patients undergoing colonoscopy for any indication.