1. Department of Gynecology, Handan Central Hospital, Handan, Hebei 056001, P.R. China
2. Department of Gynecology, Renqiu People's Hospital, Cangzhou, Hebei 062550, P.R. China
3. School of Clinical Medicine, Graduate School of Hebei University, Baoding, Hebei 071002, P.R. China
4. Department of Surgery, Handan Central Hospital, Handan, Hebei 056001, P.R. China