1. Department of Gynecology and Obstetrics, Florence-Nightingale-Hospital, Kreuzbergstraße 79, 40489 Düsseldorf, Germany
2. Department of Pathology, Evangelisches Krankenhaus Oberhausen, Virchowstraße 20, 46047 Oberhausen, Germany
3. Department of Obstetrics and Gynecology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany