1. Department of Gastroenterology, The Chengdu Fifth People's Hospital, Chengdu, Sichuan 611130, P.R. China
2. Department of Gastroenterology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
3. Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China