Middle cerebral artery velocimetry: different clinical relevance depending on umbilical velocimetry

To evaluate the role of cerebral velocimetry as a predictor of perinatal outcome in high-risk pregnancies.

Middle cerebral artery pulsatility index was measured in 576 high-risk pregnancies undergoing umbilical velocimetry. The results of both tests were evaluated with respect to the birth of small for gestational age (SGA) infants and adverse perinatal outcome, defined as perinatal death, cesarean delivery for fetal distress, or low Apgar score.

Once umbilical velocimetry was taken into account, cerebral velocimetry did not improve the prediction of fetal growth restriction or adverse perinatal outcome. Neither test was able to predict adverse perinatal outcome in normally grown fetuses. As for SGA fetuses with adverse perinatal outcome, the simultaneous assessment of both umbilical and cerebral velocimetry did not improve diagnostic accuracy (kappa index 0.37 versus 0.41 for umbilical velocimetry only). However, within the group of high-risk pregnancies with abnormal umbilical velocimetry, the risk of being SGA and having an adverse perinatal outcome was doubled (relative risk 2.1, 95% confidence interval 1.1, 4.3) if cerebral velocimetry also was abnormal.

The routine use of cerebral velocimetry in high-risk pregnancies adds little information beyond that obtained from umbilical velocimetry; however, it is useful in predicting SGA infants with adverse perinatal outcome when umbilical velocimetry is abnormal.