To investigate the risk factors for delayed bleeding after endoscopic resection of colorectal tumors.

The literature on the risk factors of delayed bleeding after endoscopic resection of colorectal tumors was retrieved combined with manual retrieval from Pubmed, Cochrane, Embase, China National Knowledge Infrastructure (CNKI) and Wanfang Database published January 2012 to December 2018. Pooled odds ratio (OR) and 95% confidence intervals (95%CI) were calculated and the heterogeneity was also assessed.

A total of 17 published studies were included, with total of 6 689 cases, of which 364 cases developed delayed bleeding after endoscopic resection (ESD 193 cases, EMR 119 cases, EPMR 52 cases), Meta analysis showed that the tumor located in the proximal colon (OR: 1.83, 95% CI: 1.31~2.56; P=0.0004), history of antithrombotic drugs (OR: 1.61, 95%CI: 1.19~2.18; P=0.002), high grade intraepithelial neoplasia or early cancer (OR: 0.63, 95%CI: 0.45~0.89; P=0.009), resection method (OR: 2.71, 95% CI: 1.32~3.51; P=0.002), bleeding during operation (OR: 2.52, 95% CI: 1.56~4.10; P=0.0002), no clip placement (OR: 2.19, 95% CI: 1.20~3.99; P=0.01), and severe submucosal fibrosis (OR: 3.67, 95% CI: 2.02~6.65; P<0.0001) were the risk factors for delayed bleeding after endoscopic resection. Moreover, age, sex, lesion size, morphology, comorbidity were not associated with delayed bleeding.

Colorectal tumor located in the proximal colon, history of anti-thrombotic drug, high grade intraepithelial neoplasia or early cancer, piecemeal resection, intraoperative hemorrhage, no clip placement, severe submucosal fibrosis were the risk factors for delayed bleeding after endoscopic resection.