1. Department of Obstetrics and Gynaecology, Malda Medical College, Malda, India;
2. Department of Obstetrics and Gynaecology, Chittaranjan Seva Sadan College of Obstetrics, Gynaecology and Child Health, Kolkata, India;
3. Department of Obstetrics and Gynaecology, ESI-PGIMSR and ESIC Medical College, Kolkata, India;
4. Department of Radiodiagnosis, Institute of Postgraduate Medical Education and Research, Kolkata, India