Fetal Growth Disturbances and Doppler

Abstract

Doppler velocimetry plays an important role in the prediction and monitoring of fetal growth restriction. In the preterm fetus at <34 weeks, presence of increased impedance to flow in the umbilical artery is the earliest and most consistent indicator of fetal growth restriction caused by placental dysfunction. The progressive increase in impedance to flow in the placental circulation associated with fetal growth restriction effects changes in the fetal circulation which can be monitored sequentially and non-invasively using Doppler velocimetry. Thus Doppler has become an invaluable tool in the monitoring of the progression of fetal compromise in preterm FGR. Doppler has the potential to optimally identify the occurrence of fetal decompensation which precedes in utero death, thus allowing prompt delivery and minimizing the occurrence of stillbirth. To understand whether prenatal Doppler will play a role in the prevention of neonatal morbidity for the very preterm growth-restricted infant (i.e., whether delivery should be prompted not by the evidence of impending death, but rather by cardiovascular compromise) further studies are required. Less clear is the benefit of Doppler when FGR occurs near term (i.e., at >34 weeks’ gestation), although preliminary evidence suggests that elevation in umbilical artery resistance indices may signal increased risk of neonatal morbidity.