Efficacy of Combination Colonoscopy Using Modified Cap-assisted and Water-exchange Colonoscopy with Prone Position in the Detection of Colorectal Adenomas: A Retrospective Study

Background: The efficacy of cap-assisted and water-exchange colonoscopy for adenoma detection, individually or in combination, is well documented but the efficacy of the combination colonoscopy using the above methods with prone position for adenoma detection is unclear. We compared the effectiveness of the combination colonoscopy using modified cap-assisted and water-exchange colonoscopy with prone position (CWP) and conventional colonoscopy (CC) for adenoma detection.Methods: A total of 746 patients who underwent either CWP or CC, performed by two board-certified gastroenterologists between December 2019 and March 2020, were investigated retrospectively. Cap-assisted colonoscopy was modified using hooking and dragging maneuver. We evaluated the polyp detection rate (PDR), adenoma detection rate (ADR), and mean number of adenomas detected per procedure (MAP). Results: There was no significant difference in sex, age, the indication of colonoscopy and quality of bowel preparation between the two groups. The PDR, ADR, and proximal MAP were significantly higher in the CWP group than the CC group (PDR: 84.9% vs. 59.8%, P < 0.001; ADR: 70.1%, vs. 49.2%, P < 0.001; proximal MAP: 1.24 vs. 0.55, P < 0.001). Amongst males, total and proximal MAP were significantly higher in the CWP group than the CC group, respectively (2.28 ± 2.24 vs. 1.49 ± 1.92, P < 0.001; 1.73 ± 1.98 vs. 0.74 ± 1.21, P < 0.001). Conclusions: Combination colonoscopy is more effective than conventional colonoscopy for the PDR, ADR, and proximal MAP. Further studies assessing the synergistic or complementary effects of the combination are needed.