Incidence of meconium abnormalities in newborn infants with cystic fibrosis.

Review of the newborn nursery notes of 87 infants who had cystic fibrosis without meconium ileus (MI) indicated that 12 of them had clinical features consistent with the meconium plug syndrome (MPS). This high incidence of meconium abnormalities suggests that MI and the MPS probably represent different gradations of the same underlying pathologic abnormality. The findings further suggest that a quantitative pilocarpine iontophoresis sweat test be performed in every newborn infant with any type of meconium abnormality, including the spontaneous passage of meconium plugs.