Short-term prophylactic biliary stenting after complete common bile duct stone removal to prevent post-ERCP cholangitis in Japan (STEP-ERCP study): study protocol for a confirmatory multicentre randomised controlled trial

Introduction: Endoscopic retrograde cholangiopancreatography (ERCP) is the standard treatment for common bile duct stones. Although complete stone removal can be achieved in most cases, post-ERCP cholangitis still occurs in a subset of patients, even in the absence of preprocedural cholangitis. Temporary prophylactic biliary stenting after complete stone extraction may reduce post-ERCP cholangitis by preventing transient biliary obstruction caused by papillary oedema, impaired bile drainage or residual biliary sludge. However, evidence supporting this strategy is currently limited to retrospective studies. The STEP-ERCP study is designed to test the hypothesis that short-term prophylactic biliary stenting after complete removal of common bile duct stones reduces the incidence of post-ERCP cholangitis compared with no biliary stenting.