1. Digestive Disease Center, Bispebjerg and Frederiksberg Hospital, University of Copenhagen , Copenhagen , Denmark
2. Department of Gastrointestinal and Hepatic Diseases, Surgical Division, Herlev and Gentofte Hospital, University of Copenhagen , Copenhagen , Denmark
3. Department of Surgery, Hvidovre Hospital, University of Copenhagen , Copenhagen , Denmark
4. Department of Surgery, Nordsjællands Hospital, University of Copenhagen , Hillerød , Denmark
5. Department of Surgery, Slagelse Hospital , Slagelse , Denmark
6. Department of Surgery, Sjælland University Hospital , Køge , Denmark