1. Department of Anorectal, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
2. Department of Gynecology, Qingdao Hospital of Traditional Chinese Medicine, Qingdao, Shandong 266000, P.R. China
3. Center of Colon and Rectum, Qingdao Municipal Hospital, Qingdao, Shandong 266011, P.R. China