[Doppler examination of the umbilical and cerebral arterial circulation of the fetus].

Umbilical circulation can be explored by Doppler ultrasound methods very easily. The umbilical arteries spectrum provides information on the placental circulation. The diastolic flow is directly related to the vascular resistances of the placenta (Rp). In cases of pathological pregnancies with hypertension the decrease in the diastolic flow and the increase in the resistance index Rp have been correlated with intra-uterine fetal growth retardation. The specificity of this index Rp is of 95% but the sensitivity much more lower (approximately 70%). For that reason Doppler assessment of the fetal circulation in other areas has been recently carried out. Fetal cerebral arteries have been explored during normal pregnancies. The index of cerebral resistances as defined by Pourcelot Rc = S-D divided by S (with S systolic amplitude and D diastolic amplitude) show similar variations to the placental index but later in the pregnancy. During the pregnancy the cerebral index is higher than the placental one and the cerebro placental ratio (CPR) superior to 1. During pathological pregnancy (hypertension) with fetal growth retardation one of the index Rc or Rp may be out of the normal range but the cerebro placental ratio CPR is always lower than 1. The follow up of both the umbilical and cerebral circulation increases notably the accuracy of the Doppler method for the detection of intra-uterine fetal growth retardation.