Duplex Doppler systems in obstetric ultrasound.

Doppler ultrasound applications in normal and complicated pregnancies are presented in this article. Anatomy and pathophysiology of fetal placental blood flow are described. Potential pitfalls in the evaluation of fetal placental blood flow are explored. Doppler flow velocity waveform analysis combined with other clinical and physiologic information is valuable in monitoring of the high-risk pregnancy. Duplex technology may also be useful in the first trimester.