1. Department of Gynecology and Obstetrics; University of Duisburg-Essen; Essen Germany
2. Department of Gynecology and Oncology and Gynecological Nursing; Ludwik Rydygier Collegium Medicum; Nicolaus Copernicus University; Bydgoszcz Poland
3. Institute for Medical Informatics; Biometry and Epidemiology (IMIBE); University of Duisburg-Essen; Essen Germany