Doppler evaluation of the posterior cerebral artery in normally grown and growth restricted fetuses.

OBJECTIVE

To evaluate Doppler parameters of the two segments of the posterior cerebral artery (PCA) in normally grown and growth restricted (IUGR) fetuses.

METHODS

Normal reference values of the pulsatility index (PI), peak systolic velocity, end-diastolic velocity, and time-averaged maximum velocity from the two segments of the PCA (segment one, PCA-S1; segment two, PCA-S2) were constructed in 350 pregnant women from 20 to 40 weeks of gestation. The association of the two PCA segments with the middle cerebral artery (MCA), and with the umbilical artery was evaluated in 50 IUGR fetuses.

RESULTS

In normal fetuses, Doppler parameters from PCA-S1 and PCA-S2 showed similar behavior throughout gestation. In IUGR fetuses, the PI of the two PCA segments was significantly reduced with no differences between them. PCA-S2 PI showed a higher correlation with the MCA-PI (r = 0.73) than PCA-S1 PI (r = 0.63; p = 0.001). IUGR fetuses showed vasodilatation in the PCA earlier than in the MCA disregarding the umbilical artery-PI value.

CONCLUSION

In IUGR fetuses, the two segments of the PCA show signs of vasodilatation earlier than the MCA. As IUGR fetuses deteriorate, the two segments of the PCA and the MCA behave similarly.