The assessment of the feto-placental circulation with continuous wave Doppler ultrasound.

Continuous wave Doppler ultrasound was used together with B-mode real time ultrasound to study feto-placental blood flow in utero. The results of 887 examinations on 221 patients are presented. The fetal heart rate acceleration slope and pulsatility index (P.I.) of the audiofrequency ultrasound display were analysed. There was a significant reduction in fetal heart rate (P less than 0.001) and P.I. (P less than 0.001) with advancing gestational age in normal pregnancy. In contrast, in retarded intrauterine growth a significant increase in P.I. values was observed in 77% of patients.