New Scientific Publication: Meta-Analysis concludes benefits of ST Analysis
The objective of this meta-analysis, which includes five randomised trials (RCT) and 15,352 patients, was to compare the effects of adding ST Analysis to conventional intrapartum CTG. The included RCT’s evaluated singleton term pregnancies in cephalic presentation and the meta-analysis was performed on results for metabolic acidosis, fetal blood sampling, mode of delivery, Apgar score and neonatal care. For three of the studies, published corrected data were used and the meta-analysis could be performed on all data according to the intention-to-treat principle.
The random effects model* was used to estimate the combined relative risk. A relative risk less than 1 indicates an effect in favour for ST Analysis.
In previously reported meta-analysis’ in the Cochrane Database, fixed-effects analysis have been used. When this model was used for the five RCTs with converted data, the reduction in metabolic acidosis became significant.
The authors conclude that intrapartum monitoring with ST Analysis is a safe method and that its implementation can lead to a reduction in operative deliveries as well as the need for fetal blood sampling. The incidence of metabolic acidosis is reduced across a majority of the studies but reaches significance only when the fixed effects model is used. Due to the among-study differences on the effect of metabolic acidosis, the authors question if this is the right outcome to investigate, but other more specific perinatal outcomes are however very rare. They also conclude that since ST Analysis reduces both the intervention rate for suspect fetal distress and the total intervention rate, this indicates that ST Analysis has a true effect on the mode of delivery and lowers the risk of operative delivery.
*A random-effects model use estimates of the within study variances as well as estimates of the among study variances.
Abstract
Obstet Gynecol. 2012 Jan;119(1):145-154.
ST Analysis of the Fetal Electrocardiogram in Intrapartum Fetal Monitoring: A Meta-Analysis.
Becker JH, Bax L, Amer-Wåhlin I, Ojala K, Vayssière C, Westerhuis ME, Mol BW, Visser GH, Maršál K, Kwee A, Moons KG.
From the Departments of Obstetrics and Gynecology, University Medical Center Utrecht, Utrecht, the Netherlands, Oulu University Hospital, Oulu, Finland, University Medical Center, Toulouse, France, Amsterdam Medical Center, Amsterdam, the Netherlands, and Lund University, Lund, Sweden; the Julius Center for Health Sciences and Primary Care, University Medical Center, Utrecht, the Netherlands; Pharsight, A Certara Company, Sunnyvale, California; and the Department of Women and Child Health, Karolinska Institute, Stockholm, Sweden.
OBJECTIVE:
To compare the effects of ST-waveform analysis in combination with cardiotocography with conventional cardiotocography for intrapartum fetal monitoring.
DATA SOURCES:
We searched MEDLINE, Embase, and PubMed for randomized controlled trials (RCTs) evaluating ST-waveform analysis for intrapartum fetal monitoring.
METHODS OF STUDY SELECTION:
We identified RCTs that compared ST-waveform analysis and conventional cardiotocography for intrapartum fetal monitoring of singleton pregnancies in cephalic presentation beyond 34 weeks of gestation and evaluating at least one of the following: metabolic acidosis, umbilical cord pH less than 7.15, umbilical cord pH less than 7.10, umbilical cord pH less than 7.05, umbilical cord pH less than 7.00, Apgar scores less than 7 at 5 minutes, admittance to the neonatal intensive care unit, need for intubation, presence of hypoxic ischemic encephalopathy, perinatal death, operative delivery, and number of fetal blood samplings.
TABULATION, INTEGRATION, AND RESULTS:
Five RCTs, which included 15,352 patients, met the selection criteria. Random-effects models were used to estimate the combined relative risks (RRs) of ST analysis compared with conventional cardiotocography. Compared with conventional cardiotocography, ST analysis showed a nonsignificant reduction in metabolic acidosis (RR 0.72, 95% confidence interval 0.43-1.19, number needed to treat [NNT] 357). ST analysis significantly reduced the incidence of additional fetal blood sampling (RR 0.59, 95% confidence interval 0.44-0.79, NNT 11), operative vaginal 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 other outcomes, no differences in effect were seen between ST analysis and conventional cardiotocography, or data were not suitable for meta-analysis.
CONCLUSION:
The additional use of ST analysis for intrapartum monitoring reduced the incidence of operative vaginal deliveries and the need for fetal blood sampling but did not reduce the incidence of metabolic acidosis at birth.