1. Department of Surgery, Virgen de la Arrixaca University Hospital, Murcia, Spain
2. University and Clinic Hospital, Santiago de Compostela La Coruña, Spain
3. 12 de Octubre University Hospital, Madrid, Spain
4. University and Clinic Hospital, Barcelona, Spain
5. La Fe University Hospital, Valencia, Spain
6. University Hospital of Bellvitge, Barcelona
7. University Hospital Puerta de Hierro, Madrid
8. University Hospital Cruces, Bilbao
9. Central University Hospital of Asturias, Oviedo
10. Virgen de la Arrixaca University Hospital, Murcia