Underwater EMR for colorectal lesions: a systematic review with meta-analysis (with video)

BACKGROUND AND AIMS: Underwater EMR is an alternative way to have nonpedunculated colorectal lesions lifted before being resected. The endoscopist takes advantage of the behavior of mucosal lesions floating away from the muscular layer, once immersed in liquid. We performed a systematic review with meta-analysis to evaluate the efficacy and safety of this technique. METHODS: Electronic databases (Medline, Scopus, EMBASE) were searched up to May 2018. Full articles including patients with colorectal lesions resected by the underwater EMR technique were eligible. The complete resection (primary outcome), en bloc resection, recurrence, and adverse event rates were pooled by means of a random or fixed-effect model. RESULTS: Ten studies were eligible, providing data on 508 lesions removed from 433 patients (male/female = 239/194; mean age range 62.2-75.0 years). Six studies were performed in the United States and the other in Europe; 7 studies were prospective. The specific indications for performing underwater EMR varied widely across studies. The complete resection rate was 96.36% (95% confidence interval [CI], 91.77-98.44), with a rate of en bloc resection of 57.07% (95% CI, 43.20%-69.91%). The recurrence rate was 8.82% (95% CI, 5.78-13.25) in a mean endoscopy surveillance period of 7.7 months (range 4-15 months). The postprocedural bleeding rate was 2.85% (95% CI, 1.64-4.90). Bleeding during the procedure was always mild and was considered as part of the procedure in all series. The overall adverse event rate was 3.31% (95% CI, 1.97%-5.52%). No cases of perforation were reported. CONCLUSION: According to the results of this systematic review, underwater EMR appears to be an effective and extremely safe technique for resecting nonpolypoid colorectal lesions.