Fetal acidosis and Doppler velocimetry of the umbilical arteries in labor.

The objective of the study was to determine whether Doppler velocimetry indices of the fetal umbilical arteries change with the development of acidosis during labor. Repeated Doppler velocimetry was performed in selected patients with high-risk labors for the purpose of evaluating whether this might be a useful test of fetal well-being in labor. The study sample comprised 36 women with singleton pregnancies, complicated either by gestational proteinuric hypertension or by intrauterine growth retardation (or both) with a normal cardiotocographic tracing at the onset of labor. The acid-base status of the fetus was assessed after delivery by analyzing the umbilical artery blood. A total of 27 fetuses were followed through labor. Six were born with an umbilical artery base deficit of more than 10 mmol/l. No change in mean Pourcelot ratio (resistance index) was noted in both normal and acidotic fetuses. None of the acidotic fetuses showed a change in Pourcelot ratio of more than 0.03. We conclude that Doppler velocimetry of the umbilical arteries, as measured by the Pourcelot ratio, does not contribute to the diagnosis of fetal acidosis in labor.