Non-reassuring fetal heart rate patterns in association with umbilical artery acidosis

INTRODUCTION: The main purpose of the study was to evaluate the clinical outcomes of fetuses who had intrapartum non-reassuring fetal heart rate tracings.
METHODS: Patients who underwent cesarean section as an emergency operation due to non-reassuring fetal heart rate patterns were included in the study. All FHR paper traces were reevaluated by an expert obstetrician, blinded to the neonatal outcomes, based on the guidelines of the NICHD workshop. Patients were placed into five groups considering the variability and accompanying deceleration type. Clinical outcomes, Apgar scores, and umbilical artery blood parameters were evaluated.
RESULTS: The study consisted of 84 patients; Group 1, normal variability with late decelerations (n=32); Group 2, normal variability with variable decelerations (n=16); Group 3, decreased variability (n=10); Group 4, decreased variability with late decelerations (n=14); Group 5, decreased variability with variable decelerations (n=12). Groups with decreased variability and decelerations (groups 4 and 5) had higher rates of NICU admission than the groups with normal variability with decelerations (groups 1 and 2) (p<0.05). In the decreased variability with late decelerations group (Group 4), umbilical artery blood pH and ABE were significantly lower while lactate levels were higher than in groups 1, 2, and 3 (p<0.001). Among all patients, inverse correlations were shown between umbilical artery blood lactate and pH (r=-0.734, p<0.001), and also between lactate and ABE (r=-0.581, p<0.001). For the prediction of umbilical artery blood pH<7.1 and/or ABE<-12, the optimal umbilical artery blood lactate cut-off level is 7 mmol/L with a sensitivity of 88.9% and specificity of 89.3%.
DISCUSSION AND CONCLUSION: Decreased variability in non-reassuring intrapartum fetal heart rate patterns should be considered as important as decelerations. In the evaluation of intrapartum fetal asphyxia, lactate appears to be as good a marker as pH and ABE.