Sessile serrated lesions (SSLs) are well-recognized precursors of colorectal carcinoma. Therefore, their complete removal is essential to reduce colorectal cancer incidence and mortality. Several endoscopic techniques have been employed for SSL resection. Among them, underwater endoscopic mucosal resection (UEMR) has been increasingly performed for nonpedunculated colorectal lesions (NPCLs). However, data regarding the efficacy and safety of UEMR specifically for SSLs remain limited. This systematic review and single-arm meta-analysis aimed to evaluate the pooled efficacy and safety of UEMR for SSLs.

PubMed, EMBASE, and Cochrane databases were searched through June 2025 for studies reporting UEMR outcomes in SSLs. The primary outcome was the complete resection rate. Secondary outcomes included en bloc resection, R0 resection, and adverse events (AEs). A random-effects model was used to pool proportions with 95% confidence intervals (CIs). Heterogeneity was assessed using the I² statistic, and sensitivity analyses were conducted using a leave-one-out approach.

Seven observational studies comprising 581 lesions were included. Median lesion size ranged from 12 to 24.6 mm across studies. The pooled complete resection rate was 90.5% (95% CI, 69.6–100). The pooled R0 resection rate was 72.5% (95% CI, 58.4–83.2), decreasing to 63.6% for lesions ≥10 mm. The en bloc resection rate was 80.4% (95% CI, 65.0–90.1). AEs were rare, with a pooled incidence of 0.56% (95% CI, 0–1.74), including six delayed bleeding at 1.03 % and five reported perforations. Recurrence was reported in three studies including 380 lesions. The pooled analysis showed a recurrence rate of 2.37% (95%CI 1.24-4.49; I²0%).

UEMR appears to be a safe and effective approach for SSLs, achieving high complete resection rates with a low incidence of AEs. The relatively favorable R0 and en bloc resection rates may contribute to low recurrence rates on surveillance. UEMR may therefore represent a suitable alternative for treating SSLs. Randomized comparative studies are needed to define the optimal endoscopic approach for these lesions.