The echogenic appearance of the lungs is can be operator dependant. Many pitfalls make impossible to standardize the fetal lungs changes during gestation. In our case the lungs appeared more echogenic than the liver, with a contrast of the shadows of the ribs. One publication tried to determine the fetal maturity by the comparison of the echogenicity of the lungs to the liver echogenicity (1).
The differential diagnosis of sonographic appearance of bilateral echogenic lungs includes:
Bilateral microcystic congenital adenomatoid malformation Stocker type III (2), Achiron type IV (3). It is usually associated with the fetal ascites and placentomegaly. The prognosis is poor (4).
Airway obstruction as prenatal tracheal obstruction caused by cartilaginous bar (5) or possibly associated with maternal pertussis infection (6).
Chicken pox during pregnancy may lead to the lung hyperechogenicity (7).
Fetal Candida infection due to retained intrauterine contraceptive device (8).
Congenital syphilis is an unusual cause of bilateral pulmonary spirochete"s abscesses (9), but no prenatal description was made.
In our case, the amniotic fluid was hyperechoic. Previous studies (10, 11, 12, 13), have shown that homogenous echogenic amniotic fluid does not necessarily signify meconium stained amniotic fluid. Sepulveda et al (10) have shown that this finding refers more often to a considerable amount of vernix caseosa, rather than meconium and is not necessarily associated with post maturity. In a prospective study of 19 twin pregnancies Petrowsky et al (13) have shown that meconium was found in 5% of echogenic amniotic fluid and in 21% of anechoic amniotic fluid.
We conclude that bilateral hyperechoic appearance of the fetal lungs associated with echogenic appearance of the amniotic fluid can be the sign of early fetal lung inflammation due to chorioamnionitis. Further observations are needed to confirm this hypothesis.
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