1. Center of Pediatric Surgery, Hannover Medical School and Bult Children's Hospital, Hannover, Germany
2. Department of Pediatric Surgery, Queen Silvia Children's Hospital, Gothenburg, Sweden
3. Department of Medical Psychology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
4. Department of Pediatrics, Institute of Clinical Sciences, Queen Silvia Children's Hospital, Gothenburg, Sweden