1. Department of Gastrointestinal Colorectal and Anal Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin, P.R. China
2. Endoscopic Center, The Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, Jilin, P.R. China
3. Department of Colorectal and Anal Surgery, The Second Hospital of Jilin University, Changchun, Jilin, P.R. China