Underwater endoscopic mucosal resection for 10-20 mm pedunculated colorectal polyps: a prospective pilot study

Abstract Background: The prophylactic application of clips for large pedunculated colorectal polyp resection may prevent postpolypectomy bleeding (PPB) but carries the risk of tumor remnants. This study assessed the effectiveness and safety of underwater endoscopic mucosal resection (UEMR) without clips before resecting large pedunculated polyps. Methods: Pedunculated polyps with a head diameter of 10-20 mm, a stalk diameter of ≥ 5 mm and a stalk length of ≥ 10 mm were eligible for inclusion and removed by UEMR without prophylactically clipping stem. The primary outcome was the rate of PPB, which included immediate PPB (IPPB) and delayed PPB (DPPB). The secondary outcomes included the rate of en bloc resection, complete resection, R0 resection and other adverse events. Results: Totally, 28 patients with 32 polyps were included in this study. The head diameter was 14.6 ± 3.5 mm. After polypectomy, two cases (6.3%) of nonactive spurting IPPB were observed, and no DPPB occurred during the follow-up period. All pedunculated polyps were successfully resected and achieved en bloc resection, complete resection and R0 resection. None of the polyps showed evidence of other severe adverse events. Conclusion: UEMR without the application of prophylactic clips has a low postpolypectomy bleeding rate and low risk of residual tumor and other severe adverse events. Therefore, it might be suitable and safe for resection of 10-20 mm pedunculated polyps. Trial registration: The study was registered on 08/04/2021 at ClinicalTrials.gov (NCT04837690).