Prophylactic clip closure after right-colon endoscopic mucosal resection in a matched cohort of 470 patients exhibits sub-site heterogeneity.

Background and study aims Clinically significant post-EMR bleeding (CSPEB) is the most common adverse event after endoscopic mucosal resection (EMR) of large non-pedunculated colorectal polyps (LNPCPs). Randomised trials of prophylactic through-the-scope clip (TTSC) closure have produced conflicting results, and it remains unclear whether the effect is uniform across right-colon sub-sites and whether complete apposition is required. We examined real-world outcomes of a universal right-colon clipping policy, with attention to sub-site heterogeneity and closure completeness. Methods Consecutive patients undergoing EMR of right-sided LNPCPs ≥20 mm (January 2020-October 2025) with prophylactic TTSC closure were identified from the prospectively maintained ACE registry, and matched 1:1 by propensity score to a no-clip comparator from the same registry (pre-2020). The primary endpoint was CSPEB within 14 days; sub-site heterogeneity and closure completeness were exploratory analyses. Results Propensity score matching yielded 235 matched pairs (n=470), well-balanced on all covariates. CSPEB occurred in 8/235 (3.4%) clipped versus 26/235 (11.1%) unclipped patients (RR 0.31, 95% CI 0.14-0.66; NNT 13; p=0.002). Exploratory sub-site analyses suggested benefit concentrated at the hepatic flexure (0% vs 17.2%; p=0.020) and ascending colon (2.0% vs 10.1%; p=0.033), with a non-significant difference at the cecum (8.2% vs 13.7%; p=0.428). Within the clipped cohort, CSPEB rates were similar with complete (5/143, 3.5%) and partial (3/92, 3.3%) closure (p=1.000). Conclusion In this single-centre analysis, TTSC closure was associated with lower CSPEB after right-colon EMR, concentrated at the hepatic flexure and ascending colon; partial apposition appeared as effective as complete closure. These hypothesis-generating observations warrant prospective evaluation.