1. Department of Obstetrics and Gynecology, Blekinge Hospital, Lasarettsvägem 38, 37185 Karlskrona, Sweden
2. Department of Obstetrics and Gynecology, Women and Children’s Division, Kirkeveien 64 A, 0364 Oslo, Norway
3. Department of Radiology, Oslo University Hospital, Ullevaal, Kirkeveien 166, N-0407 Oslo, Norway