[1] Univ Hosp Coventry & Warwickshire, Dept Obstet & Gynaecol, Coventry CV2 2DX, W Midlands, England
[2] Univ Hosp Coventry & Warwickshire, Dept Anaesthesia, Coventry CV2 2DX, W Midlands, England
[3] Univ Hosp Coventry & Warwickshire, Dept Radiol, Coventry CV2 2DX, W Midlands, England