[Continuous-wave Doppler ultrasound in the 2d and 3d trimester of pregnancy--normal values].

Based on 427 patients with uneventful pregnancies and deliveries standard rates were established for the resistance index (RI) and the pulsatility index (PI) of the uterine, arcuate, and umbilical arteries. Percentiles, above all the 90th percentile, are more suitable localisation gauge than are standard deviations. In the observation period, i.e. from 18th to 42nd week of gestation, neither resistance nor pulsatility Index in the utero-placental compartment proved to be dependent on gestational age to any significant degree. By contrast, the umbilical artery showed a definite linear relation between the indices measured and gestational age. If the heart rates are in physiological ranges no clinically relevant effects of the heart rate on the measurement results were observed in either the maternal or the foetal compartment.