Longly-attached cap can contribute to en bloc underwater endoscopic mucosal resection of 20–30 mm colorectal intramucosal lesions

Abstract

Background and study aims: Underwater endoscopic mucosal resection (UEMR) is effective for colorectal intramucosal lesions. The aim of this study was to evaluate whether a longly-attached cap in UEMR improves the en bloc resection rate for 20–30 mm lesions. Patients and methods: We performed a retrospective study at a tertiary institute. Candidates for the study were systematically retrieved from an endoscopic and pathological database from October 2016 to December 2020. We assessed the procedural outcomes with UEMR for lesions ≥ 20 mm in size and the clinical factors contributing to en bloc resection. Results: A total of 52 colorectal lesions that underwent UEMR were included. The median procedure time was 271 (66–1264) seconds. The en bloc resection rate and R0 resection rate were 75% and 73%, respectively. Intraprocedural perforation occurred in one (1.9%) case, but no bleeding occurred. Delayed bleeding occurred in one (1.9%) case, but no delayed perforation occurred. Regarding tumor size, macroscopic type, tumor location, and the presence or absence of a history of abdominal operation, there was no significant difference between the en bloc resection and piecemeal resection groups. The visibility of the whole lesion, longly-attached cap, and sessile serrated lesions were more frequently observed in the en bloc resection group than in the piecemeal resection group (P <0.001, P =0.01, and P =0.04, respectively). Multivariate analysis showed longly-attached cap was the only independent factor associated with en bloc resection (P =0.02). Conclusions: A longly-attached cap might contribute to en bloc resection.