Qing-An-Zi Wang1, Yongxiu Yang2, Xiaolei Liang1. 1. Department of Obstetrics and Gynecology, Key Laboratory for Gynecologic Oncology Gansu Province, the First Hospital of Lanzhou University, Lanzhou City, Gansu Province, 730000, PR China. 2. Department of Obstetrics and Gynecology, Key Laboratory for Gynecologic Oncology Gansu Province, the First Hospital of Lanzhou University, Lanzhou City, Gansu Province, 730000, PR China. eh0147@163.com.