Second trimester Doppler ultrasound screening of the uterine arteries differentiates between subsequent normal and poor outcomes of hypertensive pregnancy: two different pathophysiological entities?

The 'classical' concept that pregnancy-induced hypertension (PIH) and pre-eclampsia (PE) primarily originate from defective placentation in early pregnancy has been challenged recently. There is growing evidence that other factors, including maternal predisposing conditions, also play a significant role in the pathophysiology of PIH and PE. The aim of the present study was to test the hypothesis that PIH and PE with an early onset and poor pregnancy outcome is associated with defective placentation, e.g. inadequate spiral artery dilatation and subsequent reduced uteroplacental perfusion, whereas PIH and PE with normal pregnancy outcome is not. Using Doppler ultrasound, we measured the uterine artery pulsatility index (PI) in a population of 531 nulliparous women in the 22nd week of gestation. Uterine artery PI was used as an index of resistance to blood flow in the uteroplacental circulation. Outcome measures were PIH/PE with or without poor pregnancy outcome, preterm birth and intra-uterine growth restriction (IUGR). The results revealed a striking difference between PI values for PIH/PE with and without poor pregnancy outcome. Uterine artery PI in the 22nd week was increased significantly in pregnancies which developed early-onset (before 35 weeks) PIH/PE with a poor pregnancy outcome. in contrast, uterine artery PI values were normal in women who developed PIH/PE, but had a good pregnancy outcome. There was a significant correlation between 22nd week uterine artery PI and subsequent preterm birth or IUGR. Our results indicate that only PIH/PE with poor pregnancy outcome is associated with defective placentation, whereas PIH/PE with good outcome is not. These findings support the concept of heterogeneous causes of hypertensive disorders of pregnancy

Quantification of the diastolic notch in Doppler ultrasound screening of uterine arteries

Objective To investigate a new method of quantification of the diastolic notch of the flow velocity waveforms of uterine arteries in the prediction of hypertensive disorders of pregnancy. Methods Pulsed-wave Doppler was used to obtain flow velocity waveforms (FVWs) from the uterine arteries at 21-22 weeks of gestation from 531 nulliparous women and 94 multiparous women at high risk. From the FVWs, both the pulsatility index (PI) and the notch index (NI) were calculated and the predictive values for both indices were compared using logistic regression analysis for mild and severe early onset hypertensive pregnancy complications. Results Both the PI and the NI were poor predictors for mild gestational hypertension and pre-eclampsia; predictive values for severe early onset disease, however, were much better Logistic regression analysis showed the NI has no additional value compared with the Pf in the prediction of either mild or severe disease. Conclusions The NI offers the possibility to quantify the diastolic notch in uterine artery analysis. Compared to the PI, this does not lead to better predictive values for hypertensive disorders of pregnancy