Simultaneous multigate spectral Doppler imaging of the umbilical artery and placental vessels: novel ultrasound technology

Objective To establish gestational age-specific nomograms of pulsatility indices in the umbilical artery and chorionic and intraplacental vessels, using novel ultrasound technology. Study design A prospective, cross-sectional study of 160 healthy singleton pregnancies between 18 and 33 weeks of gestation. Measurements Using simultaneous multigate spectral Doppler imaging specialized hardware and software, we measured the flow velocity waveforms of the umbilical artery, chorionic and intraplacental vessels. Computerized automatic mapping calculated the pulsatility indices in regions of interest. Results Data were adequately obtained for 160 fetuses. The pulsatility index values in the three sites measured decreased with advancing gestational age; the correlation coefficients r = -0.74, r = -0.67 and r = -0.68 for the umbilical artery, chorionic and intraplacental vessels, respectively, were found to be highly statistically significant (p < 0.0001). Conclusion Simultaneous multigate spectral Doppler imaging provides simultaneous measurements of the velocity waveforms in the umbilical artery, chorionic and intraplacental vessels, and is a feasible and reproducible method of obtaining these data. The normal data presented may facilitate early detection of flow disturbances in the fetoplacental circulation.