1. Department of Hepatobiliary Surgery, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
2. Department of Hepatobiliary Surgery, Suining Central Hospital, Suining, Sichuan 629000, P.R. China
3. Department of General Surgery, Second People's Hospital of Yibin City, Yibin, Sichuan 644000, P.R. China
4. Department of Hepatobiliary Surgery, First Affiliated Hospital of Chongqing Medical University, Chongqing 400042, P.R. China