1. Department of Internal Medicine, Division of Gastroenterology, Landspitali University Hospital, Reykjavik, Iceland;
2. Department of Surgery, Division of Abdominal Surgery, Landspitali University Hospital, Reykjavik, Iceland;
3. Faculty of Medicine, University of Iceland, Reykjavik, Iceland;
4. Department of Pathology, Landspitali University Hospital, Reykjavik, Iceland