ST Analysis of the Fetal Electrocardiogram in Intrapartum Fetal Monitoring

OBJECTIVE: To compare the effects of ST-waveform anal-ysis in combination with cardiotocography with conven-tional cardiotocography for intrapartum fetal monitoring.DATA SOURCES: We searched MEDLINE, Embase, andPubMed for randomized controlled trials (RCTs) evaluatingST-waveform analysis for intrapartum fetal monitoring.METHODS OF STUDY SELECTION: We identified RCTsthat compared ST-waveform analysis and conventionalcardiotocography for intrapartum fetal monitoring ofsingleton pregnancies in cephalic presentation beyond 34weeks of gestation and evaluating at least one of thefollowing: metabolic acidosis, umbilical cord pH less than7.15, umbilical cord pH less than 7.10, umbilical cord pHless than 7.05, umbilical cord pH less than 7.00, Apgarscores less than 7 at 5 minutes, admittance to theneonatal intensive care unit, need for intubation, pres-ence of hypoxic ischemic encephalopathy, perinataldeath, operative delivery, and number of fetal bloodsamplings.TABULATION, INTEGRATION, AND RESULTS: FiveRCTs, which included 15,352 patients, met the selectioncriteria. Random-effects models were used to estimatethe combined relative risks (RRs) of ST analysis comparedwith conventional cardiotocography. Compared withconventional cardiotocography, ST analysis showed anonsignificant reduction in metabolic acidosis (RR 0.72,95% confidence interval 0.43–1.19, number needed totreat [NNT] 357). ST analysis significantly reduced theincidence of additional fetal blood sampling (RR 0.59,95% confidence interval 0.44–0.79, NNT 11), operativevaginal deliveries (RR 0.88, 95% confidence interval 0.80–0.97, NNT 64), and total operative deliveries (RR 0.94,95% confidence interval 0.89–0.99, NNT 64). For otheroutcomes, no differences in effect were seen between STanalysis and conventional cardiotocography, or datawere not suitable for meta-analysis.CONCLUSION: The additional use of ST analysis forintrapartum monitoring reduced the incidence of opera-tive vaginal deliveries and the need for fetal bloodsampling but did not reduce the incidence of metabolicacidosis at birth.