1. Department of Gynecology, The Second Hospital of Hebei Medical University, 215 Heping West Road, Shijiazhuang, Hebei 050011, China
2. Department of Gynecology III, Cangzhou Central Hospital, Cangzhou, Hebei 061000, China
3. Department of Gynecology and Obstetrics, Beijing Tsinghua Changgung Hospital, Beijing 102218, China
4. Department of Pain, Cangzhou Hospital of Integrated TCM-WM Hebei, Cangzhou, Hebei 061001, China