In the ERC group there were 36 successful and 12 failed initial ERCs, 13 repeat procedures (EUS or ERC) performed after failed or equiocal initial ERC, and two procedures during follow-up.

• 初级终点是与任意一个内镜程序（并发症）或结石的假阴性诊断相关的阴性结果患者的比率。