Objective: The aim of this study was to evaluate the accuracy of intrapartum cardiotocography in identifying acidemia at birth by umbilical cord blood gasometry in high-risk pregnancies.
Methods: This was a retrospective cohort study of singleton high-risk parturients using intrapartum cardiotocography categories I, II, and III. The presence of fetal acidemia at birth was identified by the analysis of umbilical cord arterial blood pH (<7.1). Associations between variables were determined using the chi-square test and Kruskal-Wallis tests.
Results: We included 105 cases of cardiotocography category I, 20 cases of cardiotocography category II, and 10 cases of cardiotocography category III. cardiotocography category III had a higher prevalence of cesarean sections compared to cardiotocography category I (90.0 vs. 42.9%, p<0.006). Venous pH was higher in patients with cardiotocography category I compared to cardiotocography category III (7.32 vs. 7.23, p=0.036). Prevalence of neonatal intensive care unit (NICU) admission was lower in neonates of patients with cardiotocography category I compared to cardiotocography category III (3.8 vs. 30.0%, p=0.014). Prevalence of composite adverse outcomes was lower in neonates of patients with cardiotocography category I compared to cardiotocography category II (9.5 vs. 30.0%, p=0.022) and cardiotocography category III (9.5 vs. 60.0%, p=0.0004). cardiotocography categories II and III had low sensitivity (0.05 and 0.00, respectively) and high negative predictive value (NPV) (0.84 and 0.91, respectively) for identifying fetal acidemia at birth. The three categories of intrapartum cardiotocography showed high specificities (96.0, 99.0, and 99.0%, respectively).
Conclusion: All three categories of intrapartum cardiotocography showed low sensitivity and high specificity for identifying acidemia at birth.