[1] Hosp Univ Mutua Terrassa, Secc Cirugia Pediat, Barcelona, Spain
[2] Consorci Sanitari Alt Penedes & Garraf, Barcelona, Spain
[3] Hosp Germans Tries & Pujol, Serv Cirugia Pediat, Barcelona, Spain
[4] Fundacio Docencia & Recerca Mutua Terrassa, Barcelona, Spain