Fetal electrocardiogram ST-segment analysis and prediction of neonatal acidosis

ObjectiveTo determine the diagnostic value of fetal ST-segment analysis (STAN) in predicting neonatal acidosis.MethodsThe STAN S21® was used to monitor singleton fetuses in labor with abnormal FHR. Physicians later reviewed tracings to identify any ST events dictating intervention. Outcome measures were umbilical artery pH ≤ 7.15 and pH ≤ 7.05 at birth. The sensitivity, specificity, PPV, and NPV of a significant ST event to predict both outcomes were calculated.ResultsAnalysis included 411 women. Sensitivity of a significant ST event for screening pH ≤ 7.15 (21.9%) was 38% (41/108), specificity 83% (252/303), PPV 45% (41/92) and NPV 79% (252/319), and for pH ≤ 7.05, it was (3.4%), 62.5% (10/16), 79% (313/395), 11% (10/92), and 98% (313/319), respectively.ConclusionIn a population with abnormal FHR in labor, STAN sensitivity is moderate (almost 40%) for predicting pH ≤ 7.15 and better (almost 60%) for more severe acidosis (pH ≤ 7.05).