1. Department of Pediatric Surgery, Irkutsk Municipal Pediatric Clinical Hospital, Irkutsk, Russia.
2. Department of Pediatric Surgery, Irkutsk State Medical Academy of Continuing Education, Irkutsk, Russia.
3. Department of Pediatric Surgery, Irkutsk State Medical University, Irkutsk, Russia.
4. Department of Pediatric Surgery, Kemerovo Clinical Pediatric Hospital No5, Kemerovo, Russia.
5. Department of Endoscopy, The First Saint-Petersburg State Medical University Named of Acad. I.P. Pavlov, Saint Petersburg, Russia.