[1] Univ Groningen, Div Pediat Surg, Dept Surg, Univ Med Ctr Groningen, Hanzepl 1,POB 30 001, NL-9700 RB Groningen, Netherlands
[2] Univ Groningen, Univ Med Ctr Groningen, Dept Surg, Anorectal Physiol Lab, Groningen, Netherlands
[3] Med Spectrum Twente, Dept Gastroenterol & Hepatol, Enschede, Netherlands
[4] Princess Maxima Ctr Pediat Oncol, Dept Pediat Surg, Utrecht, Netherlands
[5] Univ Maastricht, Univ Med Ctr Maastricht, Dept Pediat Surg, Maastricht, Netherlands
[6] Radboudumc, Dept Surg, Div Pediat Surg, Amalia Childrens Hosp, Nijmegen, Netherlands
[7] Univ Med Ctr Utrecht, Wilhelmina Childrens Hosp, Dept Pediat Surg, Utrecht, Netherlands
[8] Erasmus MC, Sophia Childrens Hosp, Dept Pediat Surg, Rotterdam, Netherlands
[9] Emma Childrens Hosp, Acad Med Ctr, Dept Pediat Surg, Amsterdam, Netherlands
[10] Vrije Univ Amsterdam Med Ctr, Amsterdam, Netherlands
[11] Univ Groningen, Univ Med Ctr Groningen, Dept Epidemiol, Groningen, Netherlands