Changes in fetal blood flow in hypoxemia during labor

Abstract

Objective: The aim of this study was evaluation of intrapartum Doppler velocimetry changes in fetuses with signs of fetal hypoxemia in fetal pulse oximetry (arterial hemoglobin saturation <30%).Study design: Examinations were performed on 44 women in labor with singleton pregnancies. The subject of analysis was Doppler blood flow velocimetry in umbilical cord, fetal brain and lung. In all cases the following examinations were performed: blood flow velocimetry in middle cerebral artery (MCA), umbilical artery (UA), and pulmonary vein (PV). Among fetuses with normal Doppler velocimetry at the time of admission, we selected those with cephalic presentation and non‐reassuring fetal heart rate pattern during labor. The fetuses were included to the group of fetal pulse oximetry monitoring. All cases with signs of fetal distress in ctg and intrapartum fetal arterial oxygen saturation <30% for at least 5 min were included to the study group. Fetuses with abnormal ctg and fetal oxygen saturation >30% constituted the control group.Results: Doppler indices (PI, RI) in MCA were significantly lower in the presence of reduced oxygen saturation. Pulsatility and resistance index in UA in the study group were higher, comparing to the control group. But, there was no statistically significant difference between both groups in analyzing parameters. There were no statistically significant changes in parameters describing blood flow in pulmonary veins in both studied groups.Comments: The combined intrapartum fetal monitoring, including pulse oximetry and Doppler blood flow velocimetry, proved that the reduction of fetal arterial oxygen saturation (<30%) is associated with changes in hemodynamics of fetal cerebral circulation. It has been not observed any changes in blood flow in umbilical artery and pulmonary vein in the presence of decreased fetal saturation.