The role of maternal & fetal doppler in pre-eclampsia

Pre-eclampsia is associated with significant maternal and fetal morbidity and mortality worldwide. Pregnancy complicated by preeclampsia and/or by fetal growth restriction are reported to have inadequate maternal vascular responses to placentation. This defective vascular response was due to the failure of second wave of endovascular trophoblast migration leading to both a reduced amount and depth of trophoblast invasion of myometrium followed by the development of placental hypoxia and ischemia that can be measured biophysically by means of Doppler Ultrasound. The role of Doppler in the screening and management of preeclampsia would be reviewed in here focusing on uterine artery, umbilicalartery (UA), middle cerebral artery (MCA) and ductus venosus (DV) waveforms. The commonly used flow velocity waveform (FVW) spectrum is used namely resistance index (RI), systolic/diastolic ratio (S/D) or pulsatility index (Pl). The presence or persistence of an early diastolic notch of uterine artery over 24 weeks of pregnancy is predictive of subsequent preeclampsia and or IUGR later on. Umbilical artery Pl falls with gestational age, although mean Pl is relatively stable after 30 weeks gestation. While elevated indices are predictive of adverse outcome, absent or reversed end-diastolic velocities (AREDV) are of particular significance for growth restriction. Mean MCA Pl increases to approximately 28weeks gestation and then falls to term. Progressive hypoxemia results in a reduction in MCA Pl and therefore values 5th centile are regarded as abnormal. The ratio of UA/MCA Pl has been widely used as an index of cerebral redistribution. The 9 51h centile for pulsatility index for vein (PIV) of ductus venosus FVW falls from 0.9 at 20 weeks to 0.7 at term, with values above this being regarded as abnormal. The absence or reversal of atrial systolic forward flow of DV FVW are of particular clinical significance. By using Doppler in the early detection of preeclampsia and its fetal complication namely growth restriction we can arrange the management decisions and monitoring strategy for preeclampsia.