Meconium ileus is due to obstruction of the terminal ileum with thick, viscid meconium.
It has an incidence of 1: 1,000 – 2,000 live births.
80 – 90% of neonates with meconium ileus will have cystic fibrosis (usually the first presentation), but only 15% of children with cystic fibrosis present with meconium ileus.
Reference: McHoney M, McNamara V, Wheeler R. ‘Surgery’ In: Beattie M, Champion M, editors. Essential Revision Notes in Paediatrics for the MRCPCH. 2nd ed. Pastest. (2006) Chapter 24, pg 946.