Intrapartum fetal monitoring by ST-analysis of the fetal ECG

Objective Intrapartum fetal monitoring aims to identify fetuses at risk for neonatal and long-term injury due to asphyxia. To serve this purpose, cardiotocography (CTG) combined with ST-analysis of the fetal electrocardiogram (ECG), which is a relatively new method, may be used. The main aim of this thesis was to quantify the (cost) effectiveness of intrapartum fetal monitoring by ST-analysis of the fetal ECG in women with a singleton term pregnancy in cephalic position. Methods Several studies were performed to answer the research questions addressed in this thesis. The main study was a multicentre randomised clinical trial among labouring women, who were randomly assigned to monitoring by CTG combined with ST-analysis of the fetal ECG (index group) or CTG without ST-analysis of the fetal ECG (control group). There were strict conditions for performance of fetal blood sampling (FBS). Primary outcome was metabolic acidosis defined as umbilical cord-artery pH below 7.05 combined with a base deficit calculated in the extracellular fluid compartment above 12 mmol/L. Secondary outcomes were metabolic acidosis calculated in blood, number of low Apgar scores, total neonatal admissions, admissions to Neonatal Intensive Care Unit (NICU), number of newborns with moderate to severe hypoxic ischemic encephalopathy (HIE), operative deliveries, number of cases with FBS and costs. The analysis was performed according to intention-to-treat. Secondary analyses of the trial data were performed regarding all cases with adverse neonatal outcome and deliveries monitored by ST-analysis in which FBS had been performed. Results From January 2006 to July 2008, 5667 women were randomised in the clinical trial. 2827 women were assigned to the index and 2840 to the control group. The FBS rate was 10.6% in the index group versus 20.4% in the control group (RR 0.52; 95% CI 0.46 to 0.60). The incidence of the primary outcome was 0.7% in the index group versus 1.1% in the control group (RR 0.70; 95% CI 0.38 to 1.28). When metabolic acidosis was calculated in blood, these rates were 1.6% and 2.6%, respectively (RR 0.63; 95% CI 0.42 to 0.94). The number of operative deliveries, low Apgar scores, neonatal admissions and newborns with moderate or severe HIE was comparable in both groups. Per delivery, the mean costs per patient of CTG plus ST-analysis were €29 (95% CI: - € 9 to € 77) higher than of CTG only. The incremental costs of CTG plus ST-analysis to prevent one case of metabolic acidosis (primary outcome) were €7.250 and the number needed to treat (NNT) 250. Secondary analyses showed that monitoring by ST-analysis of the fetal ECG is more specific and comprehensive, regarding the aim to detect and deliver compromised fetuses, than monitoring by CTG only. Consequent adherence to the STAN clinical guidelines may further decrease the necessity for FBS in addition to ST-analysis of the fetal ECG. Conclusions Intrapartum fetal monitoring by ST-analysis of the fetal ECG appears to be a cost-effective, less-invasive en more specific strategy than monitoring by CTG only

Heart rate variability in hypertensive pregnancy disorders: a systematic review

BACKGROUND: Hypertensive pregnancy disorders (HPD) are associated with dysfunction of the autonomic nervous system. Cardiac autonomic functions can be assessed by heart rate variability (HRV) measurements. OBJECTIVE: To study whether HRV detects differences in the function of the autonomic nervous system between pregnant women with HPD compared to normotensive pregnant women and between women with a history of a pregnancy complicated by HPD compared to women with a history of an uncomplicated pregnancy. METHODS: A systematic search was performed in Medline, EMBASE, and CENTRAL to identify studies comparing HRV between pregnant women with HPD or women with a history of HPD to women with (a history of) normotensive pregnancies. RESULTS: The search identified 523 articles of which 24 were included in this review, including 850 women with (a history of) HPD and 1205 normotensive controls. The included studies showed a large heterogenicity. A decrease in overall HRV was found in preeclampsia (PE), compared to normotensive pregnant controls. A trend is seen towards increased low frequency/high frequency-ratio in women with PE compared to normotensive pregnant controls. CONCLUSION: Our systematic review supports the hypothesis a sympathetic overdrive is found in HPD which is associated with a parasympathetic withdrawal. However, the included studies in our review showed a large diversity in the methods applied and their results

A clinical prediction model to assess the risk of operative delivery

Objective To predict instrumental vaginal delivery or caesarean section for suspected fetal distress or failure to progress. Design Secondary analysis of a randomised trial. Setting Three academic and six non-academic teaching hospitals in the Netherlands. Population 5667 labouring women with a singleton term pregnancy in cephalic presentation. Methods We developed multinomial prediction models to assess the risk of operative delivery using both antepartum (model 1) and antepartum plus intrapartum characteristics (model 2). The models were validated by bootstrapping techniques and adjusted for overfitting. Predictive performance was assessed by calibration and discrimination (area under the receiver operating characteristic), and easy-to-use nomograms were developed. Main outcome measures Incidence of instrumental vaginal delivery or caesarean section for fetal distress or failure to progress with respect to a spontaneous vaginal delivery (reference). Results 375 (6.6%) and 212 (3.6%) women had an instrumental vaginal delivery or caesarean section due to fetal distress, and 433 (7.6%) and 571 (10.1%) due to failure to progress, respectively. Predictors were age, parity, previous caesarean section, diabetes, gestational age, gender, estimated birthweight (model 1) and induction of labour, oxytocin augmentation, intrapartum fever, prolonged rupture of membranes, meconium stained amniotic fluid, epidural anaesthesia, and use of ST-analysis (model 2). Both models showed excellent calibration and the receiver operating characteristics areas were 0.70–0.78 and 0.73–0.81, respectively. Conclusion In Dutch women with a singleton term pregnancy in cephalic presentation, antepartum and intrapartum characteristics can assist in the prediction of the need for an instrumental vaginal delivery or caesarean section for fetal distress or failure to progress

New possibilities for ST analysis - A post-hoc analysis on the Dutch STAN RCT

BACKGROUND: The diagnostic value of ST analysis of the fetal electrocardiogram (fECG) during labor is uncertain. False alarms (ST events) may be explained by physiological variation of the fetal electrical heart axis. Adjusted ST events, based on a relative rather than an absolute rise from baseline, correct for this variation and may improve the diagnostic accuracy of ST analysis. AIMS: Determine the optimal cut-off for relative ST events in fECG to detect fetal metabolic acidosis. STUDY DESIGN: Post-hoc analysis on fECG tracings from the Dutch STAN trial (STAN+CTG branch). SUBJECTS: 1328 term singleton fetuses with scalp ECG tracing during labor, including 10 cases of metabolic acidosis. OUTCOME MEASURES: Cut-off value for relative ST events at the point closest to (0,1) in the receiver operating characteristic (ROC) curve with corresponding sensitivity and specificity. RESULTS: Relative baseline ST events had an optimal cut-off at an increment of 85% from baseline. Relative ST events had a sensitivity of 90% and specificity of 80%. CONCLUSIONS: Adjusting the current definition of ST events may improve ST analysis, making it independent of CTG interpretation

Cost-effectiveness of cardiotocography plus ST analysis of the fetal electrocardiogram compared with cardiotocography only

OBJECTIVE. To assess the cost-effectiveness of addition of ST analysis of the fetal electrocardiogram (ECG; STAN®) to cardiotocography (CTG) for fetal surveillance during labor compared with CTG only. DESIGN. Cost-effectiveness analysis based on a randomized clinical trial on ST analysis of the fetal ECG. SETTING. Obstetric departments of three academic and six general hospitals in The Netherlands. POPULATION. Laboring women with a singleton high-risk pregnancy, a fetus in cephalic presentation, a gestational age > 36 weeks and an indication for internal electronic fetal monitoring. METHODS. A trial-based cost-effectiveness analysis was performed froma health-care provider perspective. MAIN OUTCOME MEASURES. Primary health outcome was the incidence of metabolic acidosis measured in the umbilical artery. Direct medical costswere estimated fromstart of labor to childbirth. Cost-effectiveness was expressed as costs to prevent one case of metabolic acidosis. RESULTS. The incidence of metabolic acidosis was 0.7% in the ST-analysis group and 1.0% in the CTG-only group (relative risk 0.70; 95% confidence interval 0.38–1.28). Per delivery, the mean costs per patient of CTG plus ST analysis (n = 2 827) were €1 345 vs. €1 316 for CTG only (n=2 840), with a mean difference of €29 (95% confidence interval −€9 to €77) until childbirth. The incremental costs of ST analysis to prevent one case of metabolic acidosis were €9 667. CONCLUSIONS. The additional costs of monitoring by ST analysis of the fetal ECG are very limited when compared with monitoring by CTG only and very low compared with the total costs of delivery.Sylvia M.C. Vijgen ... Ben Willem J. Mol ... et al

Identification of cases with adverse neonatal outcome monitored by cardiotocography versus ST analysis: secondary analysis of a randomized trial

OBJECTIVE: To evaluate whether correct adherence to clinical guidelines might have led to prevention of cases with adverse neonatal outcome. DESIGN: Secondary analysis of cases with adverse outcome in a multicenter randomized clinical trial. SETTING: Nine Dutch hospitals. POPULATION: Pregnant women with a term singleton fetus in cephalic position. METHODS: Data were obtained from a randomized trial that compared monitoring by STAN® (index group) with cardiotocography (control group). In both trial arms, three observers independently assessed the fetal surveillance results in all cases with adverse neonatal outcome, to determine whether an indication for intervention was present, based on current clinical guidelines. MAIN OUTCOME MEASURES: Adverse neonatal outcome cases fulfilled one or more of the following criteria: (i) metabolic acidosis in umbilical cord artery (pH 12 mmol/L); (ii) umbilical cord artery pH < 7.00; (iii) perinatal death; and/or (iv) signs of moderate or severe hypoxic ischemic encephalopathy. RESULTS: We studied 5681 women, of whom 61 (1.1%) had an adverse outcome (26 index; 35 control). In these women, the number of performed operative deliveries for fetal distress was 18 (69.2%) and 16 (45.7%), respectively. Reassessment of all 61 cases showed that there was a fetal indication to intervene in 23 (88.5%) and 19 (57.6%) cases, respectively. In 13 (50.0%) vs. 11 (33.3%) cases, respectively, this indication occurred more than 20 min before the time of delivery, meaning that these adverse outcomes could possibly have been prevented. CONCLUSIONS: In our trial, more strict adherence to clinical guidelines could have led to additional identification and prevention of adverse outcome.Michelle E.M.H. Westerhuis ... Ben Willem J. Mol ... et al

Prediction of neonatal metaboic acidos in women with a singleton term pregnancy in cephalic presentation

We sought to predict neonatal metabolic acidosis at birth using antepartum obstetric characteristics (model 1) and additional characteristics available during labor (model 2). In 5667 laboring women from a multicenter randomized trial that had a high-risk singleton pregnancy in cephalic presentation beyond 36 weeks of gestation, we predicted neonatal metabolic acidosis. Based on literature and clinical reasoning, we selected both antepartum characteristics and characteristics that became available during labor. After univariable analyses, the predictors of the multivariable models were identified by backward stepwise selection in a logistic regression analysis. Model performance was assessed by discrimination and calibration. To correct for potential overfitting, we (internally) validated the models with bootstrapping techniques. Of 5667 neonates born alive, 107 (1.9%) had metabolic acidosis. Antepartum predictors of metabolic acidosis were gestational age, nulliparity, previous cesarean delivery, and maternal diabetes. Additional intrapartum predictors were spontaneous onset of labor and meconium-stained amniotic fluid. Calibration and discrimination were acceptable for both models (c-statistic 0.64 and 0.66, respectively). In women with a high-risk singleton term pregnancy in cephalic presentation, we identified antepartum and intrapartum factors that predict neonatal metabolic acidosis at birth

Prediction of Neonatal Metabolic Acidosis in Women with a Singleton Term Pregnancy in Cephalic Presentation

Research into fetal development and medicin