Middle cerebral artery peak systolic velocity: a new Doppler parameter in the assessment of growth-restricted fetuses.

OBJECTIVE: The aims of this study were to determine if there is a relationship between middle cerebral artery (MCA) peak systolic velocity (PSV) and perinatal mortality in preterm intrauterine growth-restricted (IUGR) fetuses, to compare the performance of MCA pulsatility index (PI), MCA-PSV and umbilical artery (UA) absent/reversed end-diastolic velocity (ARED) in predicting perinatal mortality, to determine the longitudinal changes that occur in MCA-PI and MCA-PSV in these fetuses, and to test the hypothesis that MCA-PSV can provide additional information on the prognosis of hypoxemic IUGR fetuses.

METHODS: This was a retrospective cross-sectional study of 30 IUGR fetuses (estimated fetal weight < 3(rd) percentile; UA-PI > 95% CI) in which the last MCA-PI, MCA-PSV and UA values were obtained within 8 days before delivery or fetal demise. Among the 30 fetuses, there were 10 in which at least three consecutive measurements were performed before delivery and these were used for a longitudinal study. MCA-PSV and MCA-PI values were plotted against normal reference ranges and were considered abnormal when they were above the MCA-PSV or below the MCA-PI reference ranges.

RESULTS: Gestational age at delivery ranged between 23 + 1 and 32 + 5 (median, 27 + 6) gestational weeks. Birth weight ranged from 282 to 1440 (median, 540) g. There were 11 perinatal deaths. Forward stepwise logistic regression indicated that MCA-PSV was the best parameter in the prediction of perinatal mortality (odds ratio, 14; 95% CI, 1.4-130; P < 0.05) (Nagerlke R(2) = 31). In the 10 fetuses studied longitudinally, an abnormal MCA-PI preceded the appearance of an abnormal MCA-PSV. In these fetuses, the MCA-PSV consistently showed an initial increase in velocity; before demise or the appearance of a non-reassuring test in seven fetuses, there was a decrease in blood velocity. The MCA-PI presented an inconsistent pattern.

CONCLUSIONS: In IUGR fetuses, the trends of the MCA-PI and MCA-PSV provide more clinical information than does one single measurement. A high MCA-PSV predicts perinatal mortality better than does a low MCA-PI. We propose that MCA-PSV might be valuable in the clinical assessment of IUGR fetuses that have abnormal UA Doppler.