Efficacy and safety of underwater endoscopic mucosal resection (UEMR) for non-pedunculated colorectal polyps: a prospective study IN Vietnam

INTRODUCTION: Colorectal cancer is a leading cause of global malignancy and mortality. While conventional endoscopic mucosal resection (CEMR) is the standard for removing premalignant lesions, it requires submucosal injection. Underwater EMR (UEMR) eliminates the need for injection by utilizing water immersion to achieve mucosal separation and lesion buoyancy. Prospective data from resource-limited healthcare settings like Vietnam remain scarce. METHODS: This prospective observational study was conducted at 115 People's Hospital, Ho Chi Minh City, from May to July 2025. We consecutively enrolled adults with non-pedunculated colorectal polyps measuring 10-25 mm. UEMR was performed via water immersion without routine submucosal lifting injection using an Endo Cut Q mode (ERBE VIO 200D). Primary outcomes were en bloc and R0 resection rates. Secondary outcomes included adverse events such as bleeding and perforation. RESULTS: The mean age of participants was 52.6 ± 14.2 years, with 66.7% being male. The average polyp size was 13.7 ± 5.1 mm. Most polyps were located in the rectum (35.9%) and sigmoid colon (25.6%). En bloc resection was achieved in 87.2% of cases, and histologic R0 resection in 84.6%. Immediate bleeding occurred in 5.1% (2/39) of cases, all managed successfully with endoscopic clipping. No delayed bleeding, perforation, or post-polypectomy syndrome was observed. CONCLUSIONS: UEMR is a highly effective and safe modality for resecting intermediate-sized non-pedunculated colorectal polyps in Vietnam. The high en bloc and R0 resection rates and low adverse event profile support its integration into routine practice, particularly in resource-constrained environments where cost-effectiveness and technical simplicity are essential.