1. The Second Department of Gastrointestinal Surgery, The Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
2. Nanchong Inspection Institute for Food and Drugs, The Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
3. Anorectal Department of Integrated Traditional Chinese and Western Medicine, The Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China