DOPPLER ASSESSMENT OF THE FETAL CIRCULATION IN EARLY AND LATE FETAL DEVELOPMENT

With the advent of Doppler ultrasound, fetal cardiac performance has b een studied in isolation and in relation to the fetal circulation in g eneral both under physiological and pathophysiological circumstances. In this chapter the central theme is the changes in arterial downstrea m impedance which occur relative to normal and abnormal fetal developm ent and their association with cardiac and venous flow velocity wavefo rms. Changes in arterial downstream impedance as expressed by descendi ng aorta and umbilical artery pulsatility index are observed in: (i) n ormal embryonic/early fetal development; (ii) normal late fetal develo pment associated with behavioural states, and (iii) abnormal late feta l development, in particular fetal growth retardation.