1. Department of Surgery, Medical Centre Leeuwarden, Leeuwarden, The Netherlands
2. Department of Surgery, St Jansdal Hospital, Harderwijk, The Netherlands
3. Department of Surgery, Gelderse Vallei Hospital, The Netherlands
4. Postgraduate School of Medicine, University Medical Centre Groningen, Groningen, The Netherlands
5. Department of Surgery, Ikazia Hospital, Rotterdam, the Netherlands