1. Department of Surgery, Amsterdam UMC, Location VUmc, Amsterdam, the Netherlands
2. Zuyderland Medical Centre, Sittard-Geleen and Heerlen, Dordrecht, the Netherlands
3. Gelderse Vallei Hospital, Ede, the Netherlands
4. Albert Schweitzer Hospital, Dordrecht, the Netherlands
5. Wilhelmina Hospital, Assen, the Netherlands
6. Zaans Medical Centre, Zaandam, the Netherlands
7. Rode Kruis Hospital, Beverwijk, the Netherlands
8. Noord West Hospital, Alkmaar, the Netherlands
9. Bravis Hospital, Roosendaal, the Netherlands
10. IJsselland Hospital, Cappelle aan den Ijssel, the Netherlands
11. Department of Abdominal Surgery, Jessa Hospital, Hasselt, Belgium
12. Spaarne Hospital, Hoofddorp, the Netherlands
13. Maxima Medical Centre, Veldhoven, the Netherlands
14. Dijklander Hospital, Hoorn, the Netherlands
15. Deventer Hospital, Deventer, the Netherlands
16. Isala Clinic, Zwolle, the Netherlands
17. Department of Surgery, Amsterdam UMC, Location AMC, Cancer Centre Amsterdam, Amsterdam, the Netherlands