Underwater vs conventional endoscopic mucosal resection for nonpedunculated colorectal neoplasms: A randomized...

Underwater endoscopic mucosal resection (UEMR) has been shown to be a good treatment option for the management of nonpedunculated polyps ≥ 10 mm since its introduction. However, there is a paucity of randomized controlled trials (RCTs) in Asia.

To compare the efficacy and safety of UEMR with those of conventional EMR (CEMR) in treating nonpedunculated colorectal lesions.

We carried out this RCT at a tertiary hospital from October 2022 to July 2024. Patients with nonpedunculated colorectal neoplasms ranging from 10 mm to 30 mm in size were randomly assigned to either the UEMR or CEMR group. The primary outcome was the curative resection (R0) rate. The secondary outcomes included en bloc resection, procedure time, adverse events, and the number of clips used for defect closure.

A total of 260 patients with 260 lesions (130 in each UEMR and CEMR group) were recruited. The median age was 58 (27-85) years, the male/female ratio was 1.74, and the median lesion size was 20 (10-30 mm) mm. Compared with CEMR, UEMR was associated with a significantly greater curative resection (R0) rate (98.4% vs 90.3%; P = 0.007), greater en bloc resection rate (100% vs 94.6%; P = 0.014), shorter procedure time (65 vs 185 seconds; P < 0.001), lower rate of bleeding complications (1.5% vs 10%; P = 0.003), and fewer clips used (2 vs 3; P < 0.001). No perforations were observed in either group.

Compared with CEMR, UEMR has a higher R0 rate, greater en bloc resection rate, shorter procedure time, fewer bleeding complications, and clips used in the management of nonpedunculated colorectal neoplasms.