1. Department of General Surgery, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou, Guangdong, P. R. China
2. Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Disease, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou, Guangdong, P. R. China
3. Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou, Guangdong, P. R. China
4. Department of Emergency, The Second Affiliated Hospital of Guangzhou Medical University , Guangzhou, Guangdong, P. R. China