1. Department of Surgery, University Medical Centre Leiden, Leiden, The Netherlands
2. Department of Surgery, Academic Medical Centre Amsterdam, Amsterdam, The Netherlands
3. Department of Surgery, Albert Schweitzer Hospital, Dordrecht, The Netherlands
4. Department of Surgery, Gelre Hospital, Apeldoorn, The Netherlands
5. Department of Surgery, Tergooi Hospital, Hilversum, The Netherlands
6. Department of Surgery, Spaarne Gasthuis, Hoofddorp, The Netherlands
7. University Medical Centre Utrecht, Utrecht
8. Amstelland Hospital, Amstelveen
9. Bovenij Hospital, Amsterdam
10. Slotervaart Hospital, Amsterdam
11. Maxima Medical Centre, Veldhoven
12. Westfriesgasthuis, Hoorn