1. Section of Pediatric Surgery, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
2. Surgical Department A, Odense Universitetshospital, Odense, Denmark
3. Department of Pediatric Surgery, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden
4. Department of Pediatric Surgery, Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland