This study is patient-control setting study. Firstly, from July 2007 through February 2014, all the patients who were performed ERCP will be enrolled. The inclusion criteria is the patients with common bile duct stone. The exclusion criteria is patients with biliary stenosis, PSC, retained GB stone, or who were lost to follow-up. The main outcome is the association between periampullary diverticulum, common bile duct angle, and recurrent CBD stone. This will be evaluated by univariate and multivariate analyses.