S1042 Efficacy and Safety of Underwater versus Conventional Endoscopic Mucosal Resection for Colorectal Polyps: A Systematic Review and Meta-Analysis

Abstract

Introduction: Endoscopic mucosal resection (EMR) is a commonly used endoscopic technique for removing colorectal polyps. Underwater EMR (UEMR) has recently been introduced as a potential alternative for conventional EMR (CEMR). However, its clinical outcomes compared to CEMR remains uncertain. Therefore, we conducted this meta-analysis to evaluate the efficacy and safety outcomes of UEMR compared to CEMR. Methods: We performed a comprehensive literature search using MEDLINE and EMBASE databases from inception through January 2021 for all the studies that compared UEMR with CEMR in the removal of colorectal polyps. The assessed outcomes were en bloc resection, residual/recurrent polyps on follow-up, piecemeal resection, complete macroscopic resection, complete histological resection, and overall adverse events (intraprocedural and post-procedural bleeding and perforation). Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using the random-effects model. Heterogeneity was assessed by I2 statistic. Results: A total of 13 studies including 2046 patients with 2517 polyps were included (1213 in UEMR group, 1304 in CEMR group); four were Randomized controlled studies, eight were retrospective cohort studies, and one study was prospective cohort. Seven were full-text publications and 6 were abstracts. All the results are summarized in Table 1. UEMR showed significantly better rates of en bloc resection (OR 1.51, 95% CI 1.01, 2.18, P = 0.03, I2 = 52%) (Figure 1), residual/recurrent polyps on follow-up (OR 0.35, 95% CI 0.20, 0.62, P = 0.0003, I2 = 26%), piecemeal resection (OR 0.68, 95% CI 0.49, 0.94, P = 0.02, I2 = 0%), complete macroscopic resection (OR 12.56, 95% CI 4.88, 32.33, P < 0.00001, I2 = 0%). There was no significant difference in complete histological resection (OR 1.11, 95% CI 0.63, 1.98, P = 0.71, I2 = 62%), and overall adverse events (OR 0.92, 95% CI 0.52, 1.62, P = 0.76, I2 = 61%) between the two groups. Conclusion: Compared to Conventional EMR, Underwater EMR demonstrated better rates of en bloc resection and complete macroscopic resection with lower risks of piecemeal resection and residual/recurrent polyps. However, there was no difference in terms of complete histological resection and overall adverse events between the two approaches.Table 1Figure 1.: Flowchart.