Association Between the Ulcer Status and the Risk of Delayed Bleeding after the Endoscopic Mucosal Resection of Colon.

Background and Aim: Bleeding is the most common adverse event following colonoscopic endoscopic mucosal resection (EMR). We aimed to assess the clinical outcomes of a colon EMR according to the post-EMR ulcer status and determine the risk factors of delayed postpolypectomy bleeding (DPPB) based on the post-EMR ulcer status. Methods: The medical records and endoscopic images of patients who underwent EMR of colon polyps with diameters of >= 5 mm were retrospectively reviewed by us. If any exposed vessels were observed on the post-EMR ulcer, the types of exposed vessels were classified into cut and uncut vessels. The coagulation injuries on the post-EMR ulcer were categorized as grades 1, 2, or 3. Results: In total, 505 patients with 728 polyps were examined. Exposed vessels were present in 416 post-EMR ulcers, including cut vessels in 11 (1.5%) and uncut vessels in 405 (55.6%). With regard to coagulation injury, 113 (15.5%), 443 (60.9%), and 172 (23.6%) post-EMR ulcers had grades 1, 2, and 3 injuries, respectively. DPPB was observed in 20 lesions (2.7%). Multivariate analysis indicated that a polyp size > 10 mm (odds ratio [OR], 3.354; 95% confidence interval [CI], 1.229-9.154), cut vessels (OR, 18.913; 95% CI, 3.106-115.187), and grade 3 coagulation injury (OR, 16.796; 95% CI, 1.825154.556) were associated with DPPB. Conclusions: Cut vessels and severe coagulation injury on post-EMR ulcers, as well as larger polyp size, are risk factors for DPPB. Careful inspection of post-EMR ulcers and prophylactic hemostasis, if necessary, may improve the clinical outcomes of colonoscopic EMR.