1. Department of Surgery, Amsterdam University Medical Centre , Amsterdam , The Netherlands
2. Department of Surgery, Meander Medical Centre , Amersfoort , The Netherlands
3. Department of Surgery, University Medical Centre , Groningen , The Netherlands
4. Department of Surgery, Hospital Gelderse Vallei , Ede , The Netherlands
5. Department of Surgery, Amphia Hospital , Breda , The Netherlands
6. Department of Surgery, Tergooi Hospital , Hilversum , The Netherlands
7. Department of Surgery, Laurentius Hospital , Roermond , The Netherlands
8. Department of Surgery, Canisius Wilhelmina Hospital , Nijmegen , The Netherlands
9. Department of Surgery, Diakonessenhuis , Utrecht , The Netherlands
10. Department of Surgery, St. Antonius Hospital , Nieuwegein , The Netherlands
11. Department of Surgery, Jeroen Bosch Hospital , Den Bosch , The Netherlands