Characteristics of Category II Tracings During Last Hour of Second Stage Labor in Predicting Fetal Acidosis [37H

Abstract

INTRODUCTION: Intrapartum fetal heart rate (FHR) monitoring although sensitive, lacks specificity for predicting fetal acidosis. Category II tracings, within the last hour of labor, occur in >/=96% of uncomplicated, term, laboring patients. Most result in delivery of well oxygenated neonates. Neonatal acidosis occurs in <3% of term neonates and may result in neonatal encephalopathy. Currently, there is no standard approach to management of Category II tracings. METHODS: We retrospectively reviewed Category II tracings in singleton, uncomplicated, term patients, during the last hour prior to delivery, in women who delivered neonates with cord blood pH /=8 (Group 1) and pH ≥ 7.20, base excess. RESULTS: In Group 1 (n=414), 91% of tracings exhibited good/moderate variability, 17.5% demonstrated minimal/absent variability, 13% had accelerations (≥15 bpm, lasting ≥15 secs). In Group 2 (n = 913), 97% showed moderate/good variability, 9% minimal/absent variability, 92% demonstrated accelerations (P<0.05). Duration of second stage labor was comparable in both Groups, (Group 1 = 3.5 hours, Group 2 = 3.1 hours), as were rates of chorioamnionitis, Pitocin use. Apgar scores and rates of NICU interventions were also similar in the two Groups. CONCLUSION: Minimal/decreased variability and the absence of accelerations, in Category II tracings, reliably predict fetal acidosis. Thus, expedited delivery should be considered in this clinical setting.