Underwater endoscopic submucosal dissection for colorectal tumors decreases the incidence of post‐electrocoagulation syndrome

Abstract Background and Aims Underwater endoscopic submucosal dissection (U‐ESD) is a recently developed procedure that has the potential to prevent post‐ESD coagulation syndrome (PECS) owing to its heat‐sink effect. We aimed to clarify whether U‐ESD decreases the incidence of PECS compared with conventional ESD (C‐ESD). Methods A total of 205 patients who underwent colorectal ESD (C‐ESD: 125; U‐ESD: 80) were analyzed. Propensity score matching analysis was performed to adjust for patient backgrounds. Ten C‐ESD and two U‐ESD patients with muscle damage or perforation during ESD were excluded when comparing PECS. The primary outcome was to compare the incidence of PECS between the U‐ESD and C‐ESD groups (54 matched pairs). Secondary outcomes were to compare procedural outcomes between the C‐ESD and U‐ESD groups (62 matched pairs). Results Among the 78 patients who underwent U‐ESD, PECS occurred in only one patient (1.3%). Adjusted comparisons between the U‐ESD and C‐ESD groups demonstrated a significantly lower incidence of PECS in the U‐ESD group (0% vs 11.1%; P = 0.027). Median dissection speed was significantly faster in the U‐ESD than in the C‐ESD group (10.9 mm 2 /min vs 6.9 mm 2 /min; P < 0.001). En bloc and complete resection rates were 100% in the U‐ESD group. Although perforation and delayed bleeding occurred in one patient each (1.6%) as adverse events in the U‐ESD group, there were no differences compared with the C‐ESD group. Conclusions Our study demonstrates that U‐ESD effectively decreases the incidence of PECS and is a faster and safer method for colorectal ESD.