Ana Sofia Cerdeira1, Mariana Tome2, Niall Moore3, Lee Lim2. 1. Department of Obstetrics and Gynaecology, John Radcliffe Hospital, Oxford University Hospital, NHS Foundation Trust, Oxford, UK; Nuffield Department of Women's Health and Reproductive Health, University of Oxford, Women's Centre, John Radcliffe Hospital, Oxford, UK. Electronic address: sofia.cerdeira@wrh.ox.ac.uk. 2. Department of Obstetrics and Gynaecology, John Radcliffe Hospital, Oxford University Hospital, NHS Foundation Trust, Oxford, UK. 3. Department of Radiology, John Radcliffe Hospital, Oxford University Hospital, NHS Foundation Trust, Oxford, UK.