Ming Wang1, Shu Zhang1, Qin Yang2. 1. Department of General Surgery, The Third People's Hospital of Chengdu & the Affiliated Hospital of Southwest Jiaotong University & the Second Medical School of Chengdu Affiliated to Chongqing Medical University, 82 Qinglong Street, Chengdu, Sichuan, 610031, People's Republic of China. 2. Department of General Surgery, The Third People's Hospital of Chengdu & the Affiliated Hospital of Southwest Jiaotong University & the Second Medical School of Chengdu Affiliated to Chongqing Medical University, 82 Qinglong Street, Chengdu, Sichuan, 610031, People's Republic of China. yangqin_0813@hotmail.com.