1. Department of Pediatric Surgery, Hospital Clinico Universitario de Valladolid, Valladolid, Castilla y León, Spain
2. Department of Interventional Radiology, Hospital Clinico Universitario de Valladolid, Valladolid, Castilla y León, Spain
3. Department of Pediatric Urology, Hospital Sant Joan de Deu, Barcelona, Catalunya, Spain
4. Department of Pediatric Gastroenterology, Hospital Clinico Universitario de Valladolid, Valladolid, Castilla y León, Spain