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A Randomized Trial of Intrapartum Fetal ECG ST-Segment Analysis
Editor’s comment: Prof. Jim Thornton: Intrapartum fetal ecg monitoring ineffective
Previous trials had suggested that the fetal ecg ST-Segment Analysis (STAN) monitoring device reduced both intrapartum asphyxia and Caesarean section rates. Recently doubts arose because of allegations of scientific misconduct in the largest trial from Sweden which, although not upheld, did eventually lead to a revision of the published data. Now a group from the US report a trial more than twice as large as the Swedish one. The STAN device did not improve perinatal outcomes or decrease operative-delivery rates.
It is unclear whether using fetal electrocardiographic (ECG) ST-segment analysis as an adjunct to conventional intrapartum electronic fetal heart-rate monitoring modifies intrapartum and neonatal outcomes.
We performed a multicenter trial in which women with a singleton fetus who were attempting vaginal delivery at more than 36 weeks of gestation and who had cervical dilation of 2 to 7 cm were randomly assigned to “open” or “masked” monitoring with fetal ST-segment analysis. The masked system functioned as a normal fetal heart-rate monitor. The open system displayed additional information for use when uncertain fetal heart-rate patterns were detected. The primary outcome was a composite of intrapartum fetal death, neonatal death, an Apgar score of 3 or less at 5 minutes, neonatal seizure, an umbilical-artery blood pH of 7.05 or less with a base deficit of 12 mmol per liter or more, intubation for ventilation at delivery, or neonatal encephalopathy.
A total of 11,108 patients underwent randomization; 5532 were assigned to the open group, and 5576 to the masked group. The primary outcome occurred in 52 fetuses or neonates of women in the open group (0.9%) and 40 fetuses or neonates of women in the masked group (0.7%) (relative risk, 1.31; 95% confidence interval, 0.87 to 1.98; P=0.20). Among the individual components of the primary outcome, only the frequency of a 5-minute Apgar score of 3 or less differed significantly between neonates of women in the open group and those in the masked group (0.3% vs. 0.1%, P=0.02). There were no significant between-group differences in the rate of cesarean delivery (16.9% and 16.2%, respectively; P=0.30) or any operative delivery (22.8% and 22.0%, respectively; P=0.31). Adverse events were rare and occurred with similar frequency in the two groups.
Fetal ECG ST-segment analysis used as an adjunct to conventional intrapartum electronic fetal heart-rate monitoring did not improve perinatal outcomes or decrease operative-delivery rates. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and Neoventa Medical; ClinicalTrials.gov number, NCT01131260.)