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Fetal pleural effusion is a rare finding of fluid collections in the fetal chest, outside of the lungs. There are two issues with fetal pleural effusions, namely the etiology of the effusion as well as the effect it has on the developing fetus.

Etiology of Fetal Pleural Effusion

The cause of pleural effusions is not well-understood, but pleural effusions may result from either disrupted reabsorption of lymph or overproduction of lymph. Pleural effusions are associated with chromosomal abnormalities, including Down Syndrome and Turner Syndrome, as well as other genetic syndromes. Furthermore, pleural effusions can be associated with congenital fetal infections, such as parvovirus, toxoplasmosis, and CMV. Pleural effusions may also be seen with other congenital structural malformations, such as congenital heart defects.

Evaluation of Fetal Pleural Effusion

For pregnant women with fetal pleural effusions, it is strongly recommended they undergo invasive testing (amniocentesis) for fetal karyotype, microarray, and infections. Additionally, a fetal echocardiogram should be performed to evaluate the structure of the fetal heart.

Prognosis of fetal pleural effusions strongly depends on the etiology. If the genetic, infectious, and anatomic workups are reassuring, the most likely etiology would be a lymphatic obstruction and the prognosis is more positive. In some cases, the effusions even resolve spontaneously. However, if one of the tests are abnormal, prognosis would be based on the particular condition found.

The Effect of Fetal Pleural Effusion

Regardless of the etiology, a pleural effusion can have a negative effect on the developing fetus. An enlarging effusion may compromise lung development and lead to pulmonary hypoplasia (underdeveloped lungs), which could lead to short and long-term respiratory complications in the newborn. An expanding effusion could also lead to heart compression and failure, causing fetal hydrops, which has a poor prognosis. Therefore, management of pleural effusion also involves serial monitoring for the size of the effusion and for early signs of hydrops. A fetal echocardiogram may also be helpful in identifying early signs of heart dysfunction.  In select cases, a shunt can be placed in the developing fetus to drain fluid from the lungs into the amniotic fluid.

Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!