Tian-Hao Xie1, Yan Fu2, Xiang-Xiang Ren3, Jing Zhang3. 1. Department of General Surgery, Affiliated Hospital of Hebei University, Baoding, Hebei, 071000, China. Electronic address: squall_xth@163.com. 2. Baoding First Central Hospital, Baoding, Hebei, 071000, China. 3. Department of General Surgery, Affiliated Hospital of Hebei University, Baoding, Hebei, 071000, China.