Underwater Colorectal ESD Linked to Faster Dissection, but Not Shorter Procedures

A retrospective observational study in Endoscopy compared underwater and conventional colorectal endoscopic submucosal dissection (ESD) at a tertiary referral center between May 2010 and September 2024. Of 1,649 consecutive lesions, 1,635 entered the main analysis: 914 conventional and 721 underwater ESD. Researchers used propensity score overlap weighting to assess procedural outcomes; intraoperative perforation and long-term outcomes were evaluated descriptively.

Dissection speed was higher with underwater ESD (speed ratio, 1.23; 95% CI, 1.14–1.32; p<0.001), but procedure time was similar. Failure to complete ESD was less frequent with the underwater technique, without clear differences in en bloc resection, R0 resection, or adverse events. All 56 intraoperative perforation sites were closed endoscopically, and none required emergency surgery.

Median survival follow-up was 3.09 years in the conventional group and 2.10 years in the underwater group. Deaths occurred in 27/824 (3.3%) and 3/622 (0.5%) patients, respectively, with no colorectal cancer-related deaths. These descriptive mortality figures should not be interpreted as evidence of a survival benefit. The retrospective, single-center design and unequal follow-up limit interpretation. The findings suggest a technical advantage during dissection, but its clinical relevance remains uncertain.