1. Department of Obstetrics and Gynecology, Osaka Medical College, Takatsuki, Japan
2. Department of Obstetrics and Gynecology, First Towakai Hospital, Takatsuki, Japan
3. Department of Obstetrics and Radiology, Osaka Medical College, Takatsuki, Japan
4. Department of Obstetrics and Radiology, First Towakai Hospital, Takatsuki, Japan
5. Department of Obstetrics and Pathology, Osaka Medical College, Takatsuki, Japan