Doppler Velocimetry for Fetal Surveillance: Adverse Perinatal Outcome and Fetal Hypoxia

Summary

There is ample evidence that Doppler indices from the fetal circulation can reliably predict adverse perinatal outcome in an obstetric patient population with a high prevalence of complications, such as fetal growth restriction and hypertension. This efficacy is not evident, however, in populations with a low prevalence of pregnancy complications. It is also apparent that fetal Doppler indices are capable of reflecting fetal respiratory deficiency with varying degrees of efficiency. The umbilical arterial Doppler indices are more sensitive to asphyxia than to hypoxia, whereas cerebral Doppler indices demonstrate significant sensitivity to hypoxia. Compared to fetal heart rate monitoring and the biophysical profile, umbilical artery Doppler velocimetry shows mostly similar and often superior efficacy. Furthermore, progressive fetal deterioration manifests in sequential abnormalities of the various fetal assessment parameters, starting with middle cerebral artery vasodilation and eventual progression to disappearance of the fetal heart rate variability, late deceleration, and the absence or reversal of the end-diastolic velocity in the umbilical artery. Evidently, no single testing modality should be regarded as the exclusive choice for fetal surveillance, as these tests reveal different aspects of fetal pathophysiology, often in a complementary manner. Clearly, more work is needed to determine the optimal integration of the various surveillance methods for improving perinatal outcome in a cost-effective manner.