1. Department of Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, College of Medicine, Dankook University, Seoul, Korea.
2. Department of Obstetrics and Gynecology, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Obstetrics and Gynecology, CHA Gangnam Medical Center, CHA University, Seoul, Korea.
4. Department of Radiology, Cheil General Hospital and Women's Healthcare Center, College of Medicine, Dankook University, Seoul, Korea.
5. Department of Obstetrics and Gynecology, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea.
6. Department of Obstetrics and Gynecology, Konkuk University School of Medicine, Seoul, Korea.