1. Department of Pediatric and Gastrointestinal Surgery, Oslo University Hospital, Ullevål , Oslo , Norway
2. Department of General, Visceral, Cancer and Transplantation Surgery, University of Cologne , Cologne , Germany
3. Division of Surgery and Oncology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet and Department of Upper Abdominal Diseases, Karolinska University Hospital , Stockholm , Sweden