Intraplacental spectral Doppler scanning: fetal growth classification based on Doppler velocimetry.

The purpose of the study was to develop a Doppler modality for effective assessment of the fetoplacental circulation. Calculations based upon a theoretical model were employed to predict downstream pulsatility values in the fetoplacental circulation. The clinical study included 83 pregnancies between 32 and 36 weeks of gestation. Sixty-nine women were recruited from our low-risk clinic and had uncomplicated pregnancies. Fourteen patients had complications suspected to be associated with placental pathology. All 83 patients demonstrated UA Doppler indices within the normal limits for the gestational age. The study induced intraplacental and UA Doppler waveform analyses. The ratios between intraplacental and UA PI values (at the cord insertion to the placenta) were calculated. Nineteen patients with intraplacental to UA (placental cord insertion) PI ratios > 1 (abnormal) had adverse pregnancy outcome. The study demonstrates the importance of detailed scanning of the intraplacental pulsatile waveforms and the importance of using the ratio between the intraplacental and UA Doppler indices as an additional method for evaluation of the fetoplacental circulation. The method might be proven more effective mainly in the early stages of placental disease when a relatively small number of the placental terminal arterioles are affected with a negligible effect on the UA Doppler indices, and also in the evaluation of the large placenta. A fetal growth classification based on detailed intraplacental velocimetry and cord to intraplacental flow gradient is proposed.