Underwater versus conventional endoscopic mucosal resection for superficial non-ampullary duodenal epithelial tumors ≤20mm: A systematic review and meta-analysis

Underwater endoscopic mucosal resection (UEMR) is an emerging technique for endoscopic resection of superficial non-ampullary duodenal epithelial tumors (SNADETs). However, compared to conventional EMR, its efficacy and safety has not been widely explored.We conducted a comprehensive search using the Pubmed, Embase, and Cochrane Library databases to identify studies comparing the efficacy and safety of UEMR versus EMR for SNADETs. The main outcomes examined included en bloc resection rate, R0 resection rate, recurrence rate, procedure time, and adverse events.A total of 5 studies comprising 635 patients were included. All the literature included duodenal lesions smaller than 20 mm. The pooled analysis showed that UEMR could achieve a higher en bloc resection rate (OR 1.78, 95%CI: 1.17 to 2.71, P = 0.007) and shorter procedure time (MD -4.08, 95%CI: -6.44 to -1.73, P = 0.0007) than EMR. However, the pooled results did not support a superiority of UEMR over EMR for R0 resection rate (OR 1.27; 95% CI: 0.90 to 1.81, P = 0.18) or recurrence rate (OR 0.49; 95% CI: 0.15 to 1.67, P = 0.26). The occurrence of adverse events, including postoperative bleeding, intraoperative perforation, and delayed perforation, was very low in included studies.Compared to EMR, UEMR is an effective and safe technique for SNADETs ≤20 mm.