1. Urology Centre, Albertusstraße 17, 41061 Möchengladbach, Germany
2. Department of Urology and Pediatric Urology, Hospital Viersen, 41747 Viersen, Germany
3. Department of Urology, Hospital Siegen, 57076 Siegen, Germany
4. Department of Urology, University Hospital Essen, 45147 Essen, Germany
5. Department of Urology, Hospital Ibbenbüren, 49477 Ibbenbüren, Germany