[1] Odense Univ Hosp, Surg Dept A, Sdr Blvd 29, DK-5000 Odense C, Denmark
[2] Univ Helsinki, Childrens Hosp, Dept Pediat Surg, Helsinki, Finland
[3] Oslo Univ Hosp, Rikshosp, Dept Gastr & Pediat Surg, Oslo, Norway
[4] Oslo Univ Hosp, Ulleval, Dept Gastr & Pediat Surg, Oslo, Norway
[5] Karolinska Univ Hosp, Dept Pediat Surg, Stockholm, Sweden
[6] Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden
[7] Queen Silvia Childrens Hosp, Dept Pediat Surg, Gothenburg, Sweden
[8] Uppsala Univ, Childrens Hosp, Dept Pediat Surg, Uppsala, Sweden
[9] Uppsala Univ, Dept Womens & Childrens Hlth, Uppsala, Sweden
[10] Copenhagen Univ Hosp, Rigshosp, Dept Pediat Surg, Copenhagen, Denmark
[11] Trondhe Univ Hosp, St Olavs Hosp, Dept Pediat Surg, Trondheim, Norway
[12] Odense Univ Hosp, Hans Christian Andersen Childrens Hosp, Odense, Denmark
[13] Lund Univ, Childrens Hosp, Dept Pediat, Lund, Sweden
[14] Univ Hosp, Childrens Hosp, Reykjavik, Iceland
[15] Odense Univ Hosp, Odense Patient Data Explorat Network, OPEN, Odense, Denmark