Jiang-Chun Qiao1, Zhi-Gang Chang1, Jun-Min Wei2, Yan-Nan Liu1, Hong-Yuan Cui1, Yi Zhang3. 1. Department of General Surgery, Beijing Hospital, Ministry of Health, Beijing 100730, China. 2. Department of General Surgery, Beijing Hospital, Ministry of Health, Beijing 100730, China. Email: weijunmin@263.net. 3. Department of Obstetrics and Gynecology, Beijing Hospital, Ministry of Health, Beijing 100730, China.