1. Intervention Centre; Oslo University Hospital - Rikshospitalet; Oslo Norway
2. Medical Faculty; Institute of Clinical Medicine; University of Oslo; Oslo Norway
3. Medical Faculty; Moscow State University of Medicine and Dentistry; Moscow Russia
4. Department of Gastrointestinal and Hepatobiliary Surgery; Oslo University Hospital - Rikshospitalet; Oslo Norway
5. Department of Gastrointestinal Surgery; Akershus University Hospital; Lørenskog Norway