Doppler velocimetry in obstetrics.

Doppler ultrasound velocimetry offers a noninvasive method for assessing velocities in the various components of the fetal circulation including the cardiac, umbilical, cerebral, and aortic flows. As the volumetric flow measurement in these circumstances is prone to significant errors, the major approach has been to analyze the maximum frequency shift envelope of the Doppler waveform. Numerous studies have demonstrated not only the feasibility, but also the diagnostic efficacy of this approach. The latter is particularly true in relation to the Doppler evaluation of the umbilical circulation in various complications of pregnancy. Although these findings do not establish the role of Doppler technology as a standard of practice, they clearly demonstrate its immense potential as a fetal surveillance technique.