1. Department of Surgery, University Clinic Aachen, Aachen, Germany
2. Department of Surgery, Derriford Hospital, Plymouth, UK
3. Department of Surgery, Hopital Robert Bebre, Reims, France
4. University Medical Centre, Utrecht, The Netherlands
5. Department of Surgery, Park-Klinik Weissensee, Berlin, Germany
6. Department of General Surgery, Georg-August-University-Göttingen, Göttingen, Germany
7. Department of Surgery, Juliusspital, Würzburg, Germany
8. Department of Surgery, Royal Liverpool University Hospital, Liverpool, UK