1. Second Department of Gastrointestinal Surgery, The Affiliated Hospital of North Sichuan Medical College, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
2. Department of Dermatology, Xining First People's Hospital, Xining, Qinghai 810000, P.R. China
3. Department of General Surgery, Wangcang County People's Hospital, Guangyuan, Sichuan 628200, P.R. China
4. Anorectal Department of Integrated Traditional Chinese and Western Medicine, The Affiliated Hospital of North Sichuan Medical College, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China