Lung growth and development in anencephaly and hydranencephaly.

Significant qualitative and quantitative differences were observed in the lungs of 4 of 6 infants with anencephaly and hydranencephaly. In 3 of 4 of them, the findings were explicable on the basis of the presence of associated congenital anomalies, and in the fourth there was polyhydramnios. The infants with normal lungs did not have associated congenital abnormalities. The absence of the pituitary did not correlate with the degree of development of the lungs. Studies of lung growth in anencephaly and hydranencephaly must clearly note the presence of associated anomalies because anencephaly/hydranencephaly per se may not cause pulmonary hypoplasia in the majority of cases. The most satisfactory assessment in evaluation of lung growth and development was obtained by combining morphologic findings with more than one morphometric parameter. Radial count estimation alone was found to be a poor predictor of lung maturity (morphologic age) in hypoplastic lungs. Radial count and fixed lung volume together provide a better assessment of lung growth and development than does the ratio of lung weight to body weight, which is of use only if severely depressed. The terms immaturity and hypoplasia of the lungs are not necessarily synonymous.