Efficacy and Safety of Underwater Versus Conventional Cold Snare Polypectomy for Small Colorectal Polyps: A Meta-Analysis of Randomized Controlled Trials

Abstract

Background: Conventional cold snare polypectomy (CCSP) is the standard technique for removal of small non-pedunculated colorectal polyps. However, incomplete resection remains a concern. Recent data suggested that underwater cold snare polypectomy (UCSP) with no submucosal injection may enhance resection depth and histologic clearance. We aimed to compare the two polypectomy techniques with emphasis on efficacy and safety.

Methods: We systematically searched PubMed, Embase, Cochrane Central, and ClinicalTrials.gov from inception through March 2026, for randomized controlled trials (RCTs) comparing UCSP and CCSP for 4–10 mm non-pedunculated colorectal polyps. The primary outcome was en bloc resection. Secondary outcomes included non-R0 resection, intraprocedural bleeding, histologic complete resection (R0), and perforation. Random-effects models using DerSimonian-Laird were used to calculate risk ratios (RRs) with 95% confidence intervals (95% CIs).

Results: Three RCTs met criteria (n = 822 polyps, total; UCSP 418, CCSP 404). En bloc resection was higher in UCSP compared to CCSP (RR 1.03, 95% CI 1.00–1.06, I² = 0%). UCSP increased histologic complete resection (RR 1.15, 95% CI 1.01–1.31, I² = 81.8%). Adverse events were uncommon; intraprocedural bleeding was similar between groups (RR 0.57, 95% CI 0.16–2.07, I² = 29.5%). No perforations were reported in any arm.

Conclusions: UCSP improves en bloc resection of small polyps without increasing adverse events. Further multicenter trials with longitudinal follow-up are needed to assess long-term residual disease.