Maternal and fetal artery Doppler findings in women with chronic hypertension who subsequently develop superimposed pre-eclampsia

Objective: To carry out a prospective study of Doppler velocimetry of the fetomaternal circulation in women with chronic hypertension, to evaluate whether the subsequent development of superimposed pre-eclampsia can be predicted. Study design: Serial Doppler studies of the maternal uterine and renal arteries, and fetal middle cerebral and umbilical arteries, were performed at 16-20 and at 28-32 weeks' gestation in 56 women with chronic hypertension. Pulsatility indices were compared using the Wilcoxon rank sum method. A p value of < 0.05 was considered significant. Results: Uterine artery impedance was significantly elevated as early as 16-20 and at 28-32 weeks' gestation, while the cerebroplacental ratio was lower at 28-32 weeks' gestation, in the 14 women who developed superimposed pre-eclampsia. The maternal renal artery impedance remained constant throughout gestation, regardless of the development of pre-eclampsia. Conclusions: Uterine artery Doppler velocimetry at 16-20 and at 28-32 weeks' gestation showing increased impedance is predictive for the development of superimposed pre-eclampsia in women with chronic hypertension. The cerebroplacental ratio suggested early fetal brain sparing at 28-32 weeks' gestation in these women.