1. Department of Obstetrics & Gynecology West China Second University Hospital, Sichuan University Chengdu China
2. Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education Chengdu China
3. Department of Ultrasound West China Second University Hospital, Sichuan University Chengdu China
4. Department of Radiology West China Second University Hospital, Sichuan University Chengdu China