1. Department of Medical Psychology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Department of Pediatric Surgery, Drottning Silvias barn-och ungdomssjukhus i Goteborg, Goteborg, Sweden
3. Department of Pediatric Surgery, Hannover Medical School, Hannover, Niedersachsen, Germany
4. Department of Pediatric Surgery, Child Hospital “Auf der Bult,” Hannover, Germany