Introduction: Low adenoma detection rate (ADR) is a predictor of fatal post-colonoscopy colorectal cancer. Water exchange (WE) colonoscopy significantly increased ADR compared with conventional gas (air, CO2) insufflation in several RTC. Perceived drawbacks of WE are prior studies were conducted at specialized centers and the technique is considered inefficient for routine use [Rex 2023 doi: 10.1093/gastro/goad009]. However, with increasing global emphasis on improving colonoscopy quality WE has emerged as an important and endorsed technique that independently and significantly increases ADR [Australian National Health Med Res Council 2018, ACG 2020, AGA 2021, ASGE 2022]. Simple and easily implemented refinements to WE may provide additional positive impacts in patient care. Addition of a distal straight cap attachment in combination with WE increased ADR in unpublished and retrospective reports. We sought to evaluate the impact of combining a straight vs. Daisy (sham control) cap to WE on ADR. Endocuff was included at 2 sites due to administrative issues with securing the Daisy cap.

Hypotheses: In patients undergoing screening, surveillance or FIT+ colonoscopy the combination of WE and cap-assisted colonoscopy significantly increases ADR compared with WE alone.

Method: Consented patients at 7 international centers were randomized to WE vs. WE+Cap and examined by selected members of IWATERS [International Water-Aided Techniques in Endoscopy (Education) and Research Society]. Initial study design called for the regular cap (Olympus) and Daisy cap (Remington Medical). At two of the study sites, Endocuff (Olympus) instead of Daisy cap was used due to administrative issues with the Daisy cap. (ClinicalTrial.gov NCT03566615).

Results: Table 1 shows demographic data (comparable) and insertional variables (appeared to confirm WE was correctly used). Table 2 shows the adenoma data. The number of subjects analyzed were no cap (464), regular (456), Daisy (310) and Endocuff (150). The overall ADR were 45.5%, 49.3% (P=0.240), 52.9% (P=0.043) and 58.0% (P=0.008) (all vs. no cap), respectively. Of note the regular cap was significantly different from no cap in the splenic flexure and the right-sided colon; the Daisy cap was significantly different from no cap in the splenic flexure, the right-sided colon and the cecum; the Endocuff was significantly different from no cap in the rectum, the left-sided colon, the splenic and the hepatic flexure.

Conclusion: In an international multi-center RCT, the addition of a distal Daisy cap or Endocuff, but not a regular cap, significantly increases overall ADR when WE colonoscopy is used. Since Daisy cap and Endocuff were used as sham controls, a head-to-head randomized comparison of these two attachments in WE colonoscopy is needed to fully define which is superior in adenoma detection.

Chih Wei Tseng

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