1 Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway. Electronic address: ksoreide@mac.com.
2 Department of Neurosurgery, Stavanger University Hospital, Stavanger, Norway; Faculty of Health and Medicine, University of Stavanger, Stavanger, Norway.
3 Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway.