Middle cerebral/umbilical artery resistance index ratio as sensitive parameter for fetal well-being and neonatal outcome in patients with preeclampsia: case-control study.

Aim: To evaluate the accuracy of middle cerebral/umbilical artery resistance index (C/U RI) ratio in predicting acidemia and low Apgar score at 5 minutes after birth in the infants of women with preeclampsia.

Methods: This prospective case-control study performed at Kasr El Aini University Hospital included 50 pregnant women with preeclampsia with or without intrauterine growth restriction (IUGR). Thirty women with uneventful pregnancies, matched for age, parity, and gestational age, served as controls. Ultrasound and Doppler studies were carried out to estimate fetal weight (EFW) and determine fetal biophysical profile and resistance indices of the middle cerebral and umbilical arteries. C/U RI <1.0 was considered abnormal. Apgar scores were assessed at 5 minutes after birth, and fetal cord blood sampling to determine blood pH was done immediately after delivery. Apgar score <6 at 5 minutes, neonatal acidemia (pH<7.2), and/or neonatal admission to neonatal intensive care unit (NICU) indicated neonatal morbidity.

Results: There were no significant differences in fetal biophysical profile, middle cerebral artery RI, or umbilical artery RI between the fetuses of women with preeclampsia and those in the control group. C/U RI <1.0 was found in significantly more fetuses of women with preeclampsia than in their controls (0.7-/+0.3 and 1.3-/+0.7, respectively; P<0.001). In the preeclampsia group, C/U RI was abnormal in 32 out of 38 fetuses with IUGR, and in only 5 out of 12 of fetuses without IUGR. Neonatal acidemia was found in 30 out of 38 newborns with IUGR and in 3 out of 12 of newborns without IUGR. Preeclampsia and C/U RI <1.0 carried a relative risk of 1.4 for neonatal morbidity (neonatal academia pH<7.2, 5-minute Apgar score <6, and/or admission to NICU). C/U RI had 64.1% sensitivity, 72.7% specificity, 89.2% positive predictive value, and 36.3% negative predictive value for neonatal morbidity.

Conclusion: There was a strong correlation between the C/U RI and neonatal outcome in women with preeclampsia. C/U RI <1.0 may be helpful in the identification of newborns at risk of morbidity, irrespective of whether they are small or appropriate for their gestational age.