1. Colorectal Unit, Department of Surgery, Hospital Universitari Vall d'Hebron, Barcelona
2. Colorectal Unit, Department of Surgery, Complejo Hospitalario de Navarra
3. Colorectal Unit, Department of Surgery, Hospital Universitari del Mar, Universitat Autònoma de Barcelona, Barcelona
4. Health Science Department, Public University of Navarra, Pamplona, Spain
5. Virgen Arrixaca University Hospital, Murcia
6. Bellvitge University Hospital, Barcelona
7. Complejo Hospitalario de Navarra Hospital, Panplona
8. Clínico University Hospital, Valencia
9. Josep Trueta University Hospital, Girona
10. Sagunto Hospital, Sagunto
11. Vall de Hebrón University Hospital, Barcelona
12. La Fe University Hospital, Valencia
13. Complejo Hospitalario Ourense, Ourense
14. Germans Trias i Pujol University Hospital, Barcelona
15. Lluis Alcanyis Hospital, Xativa
16. Complejo Asistencial Burgos Hospital, Burgos
17. del Mar University Hospital, Barcelona
18. Meixoeiro Hospital, Vigo
19. Complejo Asistencial Salamanca University Hospital, Salamanca
20. Gregorio Marañón University Hospital, Madrid
21. Torrecárdenas University Hospital, Almeria
22. Hospital General Universitario, Valencia
23. Txagorritxu Hospital, Vitoria
24. Donostia University Hospital, Donostia
25. Reina Sofía University Hospital, Cordoba
26. Juan Ramón Jiménez University Hospital, Huelva