[Fetal hemodynamics assessed by transvaginal color flow mapping during the first and early second trimesters]

The present study has been carried out to evaluate the usefulness of transvaginal color flow mapping in the assessment of fetal hemodynamics during the first and early second trimesters. Forty normal fetuses were examined by transvaginal color flow mapping from 12 to 20 weeks of gestation. Maximum velocity in the transmitral (MVmax), transtricuspid (TVmax), transaortic (AVmax), fetal descending aorta (Vmax) and fetal internal carotid artery (ICVmax) was assessed. The systolic/diastolic ratio and pulsatility index (PI) of umbilical artery was also assessed. The detection rates for the fetal and umbilical flow velocity waveforms were 42.5%-85.0%. In particular, intracardiac blood flow velocity was easy to detect by transvaginal color flow mapping. The Vmax, ICVmax, MVmax, TVmax and AVmax increased significantly with advancing gestation in the normal fetuses. The TVmax was lower than the MVmax during the first and early second trimesters. Transvaginal color flow mapping studies can improve the understanding of the characteristics of fetal blood flow during the first and second early trimesters. Thus it seems to be useful in making an accurate antenatal diagnosis of congenital heart disease earlier.