Middle cerebral artery velocity waveforms in fetuses with absent umbilical artery end-diastolic flow.

Middle cerebral artery (MCA) velocity waveforms were analyzed in 21 fetuses with absent umbilical artery end-diastolic flow (AEDF). Resistance index (RI) was measured from MCA velocity waveforms when AEDF was observed for the first time and at consecutive examinations. Fetal distress defined by fetal heart rate monitoring was found in 19 cases (90%). The difference between MCA RI values of first and last examinations was statistically significant (p < 0.01). There was a positive correlation between MCA RI values at the first examination and the time passing to delivery (r = 0.52; p < 0.05). There was no significant correlation between MCA RI values and the incidence of an adverse perinatal outcome. Pregnancies with AEDF are of high risk for the development of fetal distress. MCA resistance index values decrease gradually in fetuses with AEDF suggesting continuous reduction of cerebral vascular resistance during chronic fetal hypoxia.