1 Department of Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China.
2 Department of General Surgery, Qijiang District People's Hospital, Chongqing, 401420, China.
3 Department of Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China. Electronic address: cyzhangwei@hotmail.com.