Fetal pericardial effusions (FPE) occur when there is an accumulation of pericardial fluid in utero. In order to be considered as abnormal, it is generally accepted that the pericardial fluid thickness should be greater than 2 mm.
The estimated incidence is at ~ 2% of pregnancies 8.
- a fetal pericardial effusion can occur as a component of hydrops fetalis: where it is usually one of the earliest findings in hydrops 9
- fetal arrhythmia(s):
- congenital cardiac anomalies: especially if large 5
- fetal cardiac tumours: e.g. fetal pericardial teratoma
- increased incidence of chromosomal anomalies 3,5:
A fetal pericardial effusion is typically seen as anechoic fluid component greater than 2 mm surrounding the heart (similar to adults). There is no colour flow with Doppler interrogation (c.f. congential cardiac diverticulum 6). If the volume is relatively small, it may present as a lenticular or ovoid collection whereas larger pericardial effusion may give a heart beating in a "bag of water" type appearance.
A careful search for other associations (inclusive of features of hydrops) is recommended.
In the absence of other sonographic abnormalities, an isolated fetal pericardial fluid collection up to 7 mm in thickness is not thought to be associated with an adverse outcome 1.
For a small atypical effusion consider
- congenital cardiac diverticulum: demonstrates colour flow within
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- 6. Perlitz Y, Mukary M, Lorber A et-al. Prenatal diagnosis of fetal cardiac right ventricular diverticulum disappearing at three months of age. A case report and literature review. Fetal. Diagn. Ther. 2009;25 (1): 44-6. doi:10.1159/000196815 - Pubmed citation
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- 9. Entezami M, Albig M, Knoll U et-al. Ultrasound Diagnosis of Fetal Anomalies. Thieme. (2003) ISBN:1588902129. Read it at Google Books - Find it at Amazon