1. Department of Hepatobiliary Surgery, The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia 010050, P.R. China
2. Department of General Surgery, Erenhot Hospital, Erenhot, Inner Mongolia 011100, P.R. China
3. Department of Emergency Surgery, The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia 010050, P.R China