Normal pericardial fluid in the fetus: color and spectral Doppler analysis

OBJECTIVES: To estimate the incidence of sonographic identification of pericardial fluid in normal fetuses and to evaluate the flow pattern of pericardial fluid by using color and spectral Doppler techniques. METHODS: We evaluated 27 normal fetuses for the presence of pericardial fluid by using gray-scale two-dimensional and M-mode ultrasound, and color and spectral Doppler techniques. RESULTS: Pericardial fluid was detected in 52% of cases by two-dimensional and M-mode ultrasound and in 81% of cases by color Doppler. The pericardial fluid moved towards the ventricles during systole and towards the atria during diastole. In 9 of 22 fetuses with pericardial fluid identified by color Doppler, spectral waveforms were obtained. The waveforms confirmed the bidirectional flow pattern identified at color Doppler. In six cases there was monophasic systolic and biphasic diastolic flow. In the remaining three cases, the flow was monophasic during both systole and diastole. CONCLUSIONS: Pericardial fluid can be identified with color Doppler in the majority of normal fetuses. It characteristically shows bidirectional flow as it moves with ventricular systole and diastole. Spectral waveforms can be obtained from the pericardial fluid. The presence of pericardial fluid per se should not be considered as abnormal. Color-coded pericardial fluid should not be mistaken for coronary artery blood flow.