An Updated Meta-analysis of Studies Comparing Conventional to Underwater Endoscopic Mucosal Resection for Colorectal Polyps

Background Underwater endoscopic mucosal resection (UEMR) is an emerging alternative to conventional endoscopic mucosal resection (CEMR). We intended to compare both techniques for colorectal polyp resection. Methods A comprehensive search of several databases to identify studies published until November 2021 was performed. Inclusion criteria included studies comparing UEMR to CEMR in adult patients. The calculation was done by standard meta-analysis methodology, and heterogeneity was assessed using the I2% statistics. Results 1029 polyps were resected with the CEMR technique and 1078 polyps with UEMR. UEMR was associated with an increase in the rate of overall en-bloc resection (Odds ratios (OR) 1.77; 95% CI, 1.42-2.22; P < .0001; I2 = 20%). Subgroup analysis showed an increase in the rates of en-bloc resection in polyps greater than 20 mm (OR 1.62; 95% CI, 1.17-2.25; P = 0.004; I2 = 33%). There was a reduction in the recurrence rate of polyps (P < 0.0001) in the UEMR cohort. Post-procedural bleeding or risk of perforation was not increased in either group. Resection times were shorter in UEMR (Mean difference, -8.09; P = 0.006). Conclusion UEMR is associated with lower recurrence rates and shorter procedure duration. In the future, UEMR may become the standard technique for colorectal polypectomy.