F Li1, F Zhang1, D Tan1, J Ye1,2, W Tong3. 1. Department of General Surgery, Daping Hospital, Army Medical University, Chongqing, 400042, China. 2. Department of General Surgery, The People's Hospital of Shapingba District, Chongqing, China. 3. Department of General Surgery, Daping Hospital, Army Medical University, Chongqing, 400042, China. vdtong@163.com.