1. Department of Gastrointestinal Endoscopy, Guangzhou, Guangdong, China
2. Department of Colorectal Surgery, Guangzhou, Guangdong, China
3. Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Guangdong Institute of Gastroenterology, Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China