The CT appearances of delayed amniotic fluid clearance from the lungs in an infant with absent pulmonary valve and congenital lobar emphysema.

Congenital lobar emphysema (CLE) is a cause of severe neonatal respiratory distress. Overexpansion of the affected pulmonary lobe in the fetus is due to narrowing of the airway, with a resultant 'ball-valve' effect. At birth, there may be delayed clearance of fetal lung fluid. Early chest radiographs show opacification of the hyperexpanded lobe. The CT findings in the immediate neonatal period have not been previously reported. We describe the imaging in a neonate with tetralogy of Fallot and absent pulmonary valve with secondary CLE. CT demonstrates the hyperexpanded lobe with initial thickening of the interlobular septa and alveolar ground glass attenuation, with subsequent clearing. This resorption of fetal lung fluid via the pulmonary interstitium should not be confused with interstitial lung disease.