[Obstetric Doppler--justified i high-risk pregnancies]

Doppler ultrasound is a well established technique for evaluating impedance to blood flow. A review of current literature in the field yields convincing support for the use of obstetric Doppler ultrasonography in the management of high-risk pregnancies. By measuring the pulsatility index of Doppler blood flow velocity waveforms in the umbilical and uterine arteries, it is possible to obtain accurate information on the placental circulation. Meta-analysis of 12 randomised studies showed perinatal mortality to have been significantly reduced as a result of Doppler measurements of umbilical artery blood flow in high-risk pregnancies. However, every technique has its limitations, and it should be borne in mind that even if fetal hypoxia is often revealed by an abnormal Doppler ultrasound result before the cardiotocography pattern becomes abnormal, it is nonetheless a late sign. It is concluded in the article that Doppler ultrasonography needs to be combined with other methods, such as the measurement of biochemical markers, to ensure satisfactory fetal monitoring.