['For patients receiving endoscopic submucosal dissection (ESD), there is urgent need pertaining to the prevention of postoperative bleeding. We conducted a retrospective propensity score-matched study that evaluated whether pre-ESD gastric lavage prevents postoperative bleeding after ESD for gastric neoplasms.', 'From September 2002 to October 2015, the 760 consecutive patients receiving ESD for gastric neoplasm were enrolled and data regarding them were retrospectively analyzed. All patients received conventional preventive treatment against delayed bleeding after ESD, including the administration of proton pump inhibitor and preventive coagulation of visible vessels, at the end of the ESD procedure.', 'Pre-ESD risk factors for postoperative bleeding included tumor size and no gastric lavage. Using multivariate analysis tumor size >2.0 cm (HR 2.90, 95% CI 1.65-5.10, p = 0.0002) and no gastric lavage (HR 3.20, 95% CI 1.13-9.11, p = 0.029) were found to be independent risk factors. Next, we evaluated the effect of gastric lavage on the prevention of post-ESD bleeding using a propensity score-matching method. A total of 284 subjects (142 per group) were selected. Adjusted odds ratio of gastric lavage for post-ESD bleeding was 0.25 (95% CI 0.071-0.886, p = 0.032).'] Does pretreatment Gastric Lavage reduce Postoperative Bleeding after Endoscopic Submucosal Dissection for Gastric Neoplasms?