Fetal lung hyperechogenicity: prenatal ultrasonographic diagnosis, natural history and neonatal outcome.

The ultrasonographic appearance of fetal lung hyperechogenicity is most commonly associated with congenital bronchopulmonary abnormalities, such as cystic adenomatoid malformation or pulmonary lobar sequestration. Spontaneous disappearance of echogenic lung lesions has rarely been reported, mainly due to in utero resolution of cystic adenomatoid malformation. We describe four fetuses with echogenic lungs detected prenatally, none of them having been proved to have adenomatoid malformation or pulmonary sequestration of the lungs. Color Doppler sonography was used prenatally in all cases to rule out pulmonary sequestration. Three of the four fetuses showed complete resolution of the lung lesions during gestation, with normal neonatal outcome, but in one where the lesion decreased in size, intrauterine demise occurred at 28 weeks' gestation before complete resolution, and pneumonia was found at autopsy. We suggest that fetal lung hyperechogenicity may result from in utero bronchial tree obstruction with retention of mucoid fluid distal to the obstruction. With advancing gestation, in some cases the relative obstruction may be relieved, and the sonographic appearance of the lungs may return to normal. A retention of mucus in the bronchial tree should be added to the differential diagnosis of hyperechogenic lung lesions detected by antenatal ultrasound examination.