[1] Univ Manchester, Acad Unit Obstet & Gynaecol, Sch Canc & Imaging Sci, Manchester, Lancs, England
[2] Royal Free Hosp, Dept Gynaecol, London NW3 2QG, England
[3] NHS Canc Screening Programmes, Sheffield, S Yorkshire, England
[4] Univ Aberdeen, Dept Gynaecol, Aberdeen, Scotland
[5] Cent Manchester & Manchester Childrens Univ Hosp, Colposcopy Unit, Manchester, Lancs, England
[6] Royal Infirm, Dept Lab Sci, Specialist Virol Ctr, Edinburgh, Midlothian, Scotland