Clinical Outcomes of Underwater Endoscopic Submucosal Dissection for Duodenal Tumors: A Systematic Review and Meta‐Analysis

Background and Study Aim Underwater endoscopic submucosal dissection (U‐ESD) has recently been introduced as a technique that may improve visualization and submucosal layer expansion. However, the clinical outcomes of U‐ESD for duodenal tumors have not been systematically evaluated. This study aimed to assess the efficacy and safety of U‐ESD for duodenal tumors through a systematic review and meta‐analysis. Patients and Methods A comprehensive literature search was conducted using PubMed, Scopus, and the Cochrane Library from database inception to December 12, 2025. Studies evaluating U‐ESD for duodenal tumors were included. Primary outcomes included en bloc resection, R0 resection, procedure time, adverse events, and complete mucosal defect closure. Pooled estimates were calculated using a random‐effects model. Results Four retrospective studies comprising 298 lesions treated with U‐ESD were included. The pooled procedure time was 59 min (95% CI, 48–70 min; I 2 = 72%). The pooled en bloc resection rate was 99% (95% CI, 97%–100%; I 2 = 0%), and the pooled R0 resection rate was 89% (95% CI, 81%–93%; I 2 = 54%). The pooled intraoperative perforation rate was 5% (95% CI, 1%–23%; I 2 = 88%). The pooled delayed perforation and delayed bleeding rates were 1% (95% CI, 0%–3%; I 2 = 0%) and 2% (95% CI, 1%–5%; I 2 = 0%), respectively. Conclusion Current evidence suggests that U‐ESD is a feasible treatment option for duodenal tumors and is associated with favorable clinical outcomes. However, the available evidence remains limited, and potential biases and concerns regarding generalizability warrant cautious interpretation of these findings.