Airazat M Kazaryan1,2,3, Eivind A Warberg4, Tom Mala5. 1. Department of Gastrointestinal Surgery, Østfold Hospital Trust, Grålum, Norway. kazaryan@gmail.com. 2. Chair of Faculty Surgery N2, I.M.Sechenov First Moscow State Medical University, Moscow, Russia. kazaryan@gmail.com. 3. Department of Surgery N1, Yerevan State Medical University after M. Heratsi, Yerevan, Armenia. kazaryan@gmail.com. 4. Department of Gastrointestinal Surgery, Østfold Hospital Trust, Grålum, Norway. 5. Department of Gastrointestinal Surgery, Oslo University Hospital - Ullevål, Oslo, Norway.