1. Research Institute, Medical University Pleven, 5800 Pleven, Bulgaria
2. Department of Gynecology, Hospital “Saint Anna”, Medical University, 9002 Varna, Bulgaria
3. Department of Obstetrics and Gynecology, Helios Hospital Müllheim, 79379 Müllheim, Germany
4. Faculty Associate, Medical Center, University of Freiburg, 79106 Freiburg, Germany
5. Department of Gynecologic Oncology, Medical University Pleven, 5800 Pleven, Bulgaria