Doppler ultrasonography in high-risk pregnancies: systematic review with meta-analysis

Our objective was to review all available (published and unpublished) randomized controlled trials of Doppler ultrasonography of the umbilical artery in high-risk pregnancies.

Only completed randomized controlled trials were included and reviewed according to the prespecified protocol. Data were sought for 24 prespecified perinatal outcomes. All meta-analyses were based on the "intention to treat." Primary outcome was defined as perinatal death (any death in utero or postnatally recorded during duration of individual randomized controlled trial). Reported perinatal outcomes that were not prespecified were meta-analyzed on a post hoc basis.

Twenty randomized controlled trials of Doppler ultrasonography were identified; 12 fulfilled the prespecified criteria. Meta-analysis shows a significant reduction in the number of antenatal admissions (44%, 95% confidence interval 28% to 57%), inductions of labor (20%, 95% confidence interval 10% to 28%), and cesarean sections for fetal distress (52%, 95% confidence interval 24% to 69%) in the Doppler group and that the clinical action guided by Doppler ultrasonography reduces the odds of perinatal death by 38% (95% confidence interval 15% to 55%). The reduction in perinatal deaths was also observed in five mortality subgroups (i.e., stillbirths, neonatal deaths, deaths of normally formed babies, normally formed stillbirths, and deaths of normally formed neonates). Post hoc analyses revealed a statistically significant reduction in elective delivery, intrapartum fetal distress, and hypoxic encephalopathy in the Doppler group.

There is now compelling evidence that women with high-risk pregnancies, including preeclampsia and suspected intrauterine growth retardation, should have access to Doppler ultrasonographic study of umbilical artery waveforms.