Jun Bu1,2, Xiaoting Wu3. 1. Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China. 2. Department of General Surgery, The Second People's Hospital of Chengdu, Chengdu, 610000, Sichuan Province, People's Republic of China. 3. Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China. bjxjoy@sina.com.