fetal pleural effusion

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Fetal pleural effusions (FPE) refer to an accumulation of pleural fluid in utero. It can refer to either a fetal chylothorax or a fetal hydrothorax.

Pathology

A fetal pleural effusion can occur as part of hydrops fetalis, in association with other anomalies without hydrops or in isolation - primary pleural effusion/primary fetal hydrothorax (PFHT).

Causes

Any cause of hydrops fetalis is a potential etiological factor in a fetal pleural effusion.

Associations

In addition to hydrops fetalis, a pleural effusion can be associated with numerous other underlying anomalies:

congenital cardiac anomalies: ~ 5% of non hydropic pleural effusions
underlying congenital lung anomalies
- pulmonary lymphangiectasia
- congenital pulmonary airway malformation
- bronchopulmonary sequestration
- congenital diaphragmatic herniation
- chest wall hamartoma
- pulmonary venous atresia
chromosomal anomalies (can be present in ~ 50% with an additional sonographic abnormality and ~ 12% without an additional sonographic abnormality )
- Down syndrome: ~ 20% (range 5-33%) of non hydropic pleural effusions
- Turner syndrome: especially with a 1 trimester pleural effusion
- trisomy 18:
polydactyly: ~ 1% of non hydropic pleural effusions

Radiographic features

Antenatal ultrasound

Classically seen as anechoic fluid surrounding one or both the lungs (which are echogenic) - batwing appearance.

Ancillary sonographic features include:

may show other features of hydrops if it occurs in association
there maybe presence of polyhydramnios (if severe)

Treatment and prognosis

The clinical course is variable and dependent on etiology. The presence of a pleural effusion early in pregnancy (i.e. first trimester) is often associated with a poor fetal outcome .

Management options are also dependent on other underlying factors: