A critical appraisal of the evidence for using cardiotocography plus ECG ST interval analysis for fetal surveillance in labor. Part II: the meta-analyses

ST waveform analysis vs cardiotocography alone for intrapartum fetal monitoring: An updated systematic review and meta-analysis of randomized trials

INTRODUCTION

ST waveform analysis (STAN) was introduced as an adjunct to cardiotocography (CTG) to improve neonatal and maternal outcomes. The aim of the present study was to quantify the efficacy of STAN vs CTG and assess the quality of the evidence using GRADE.

MATERIAL AND METHODS

We performed systematic literature searches to identify randomized controlled trials and assessed included studies for risk of bias. We performed meta-analyses, calculating pooled risk ratio (RR) or Peto odds ratio (OR). We also performed post hoc trial sequential analyses for selected outcomes to assess the risk of false-positive results and the need for additional studies.

RESULTS

Nine randomized controlled trials including 28 729 women were included in the meta-analysis. There were no differences between the groups in operative deliveries for fetal distress (10.9 vs 11.1%; RR 0.96; 95% confidence interval [CI] 0.82-1.11). STAN was associated with a significantly lower rate of metabolic acidosis (0.45% vs 0.68%; Peto OR 0.66; 95% CI 0.48-0.90). Accordingly, 441 women need to be monitored with STAN instead of CTG alone to prevent one case of metabolic acidosis. Women allocated to STAN had a reduced risk of fetal blood sampling compared with women allocated to conventional CTG monitoring (12.5% vs 19.6%; RR 0.62; 95% CI 0.49-0.80). The quality of the evidence was high to moderate.

CONCLUSIONS

Absolute effects of STAN were minor and the clinical significance of the observed reduction in metabolic acidosis is questioned. There is insufficient evidence to state that STAN as an adjunct to CTG leads to important clinical benefits compared with CTG alone.

Improving the interpretation of electronic fetal monitoring: the fetal reserve index

Electronic fetal monitoring, particularly in the form of cardiotocography, forms the centerpiece of labor management. Initially successfully designed for stillbirth prevention, there was hope to also include prediction and prevention of fetal acidosis and its sequelae. With the routine use of electronic fetal monitoring, the cesarean delivery rate increased from <5% in the 1970s to >30% at present. Most at-risk cases produced healthy babies, resulting in part from considerable confusion as to the differences between diagnostic and screening tests. Electronic fetal monitoring is clearly a screening test. Multiple attempts have aimed at enhancing its ability to accurately distinguish babies at risk of in utero injury from those who are not and to do this in a timely manner so that appropriate intervention can be performed. Even key electronic fetal monitoring opinion leaders admit that this goal has yet to be achieved. Our group has developed a modified approach called the "Fetal Reserve Index" that contextualizes the findings of electronic fetal monitoring by formally including the presence of maternal, fetal, and obstetrical risk factors and increased uterine contraction frequencies and breaking up the tracing into 4 quantifiable components (heart rate, variability, decelerations, and accelerations). The result is a quantitative 8-point metric, with each variable being weighted equally in version 1.0. In multiple previously published refereed papers, we have shown that in head-to-head studies comparing the fetal reserve index with the American College of Obstetricians and Gynecologists' fetal heart rate categories, the fetal reserve index more accurately identifies babies born with cerebral palsy and could also reduce the rates of emergency cesarean delivery and vaginal operative deliveries. We found that the fetal reserve index scores and fetal pH and base excess actually begin to fall earlier in the first stage of labor than was commonly appreciated, and the fetal reserve index provides a good surrogate for pH and base excess values. Finally, the last fetal reserve index score before delivery combined with early analysis of neonatal heart rate and acid/base balance shows that the period of risk for neonatal neurologic impairment can continue for the first 30 minutes of life and requires much closer neonatal observation than is currently being done.

Cardiotocography combined with ST analysis versus cardiotocography combined with fetal blood sampling in deliveries with abnormal CTG: a randomized trial

PURPOSE

The aim was to investigate if intrapartum monitoring with cardiotocography (CTG) in combination with ST analysis (STAN) results in an improved perinatal outcome.

METHODS

We performed a two-center randomized trial. 1013 women with term fetuses in cephalic presentation entered the trial. If a CTG showed intermediate or pathological abnormalities, they were offered fetal blood sampling (FBS) and inclusion if the pH value was above 7.25. They were randomized to either CTG + FBS or CTG + STAN. The primary outcome was neonatal metabolic acidosis, defined as umbilical cord arterial blood pH below 7.05, and base excess equal to or below -10. The secondary outcomes included operative vaginal delivery for fetal distress.

RESULTS

The rate of metabolic acidosis was 0.8% in the CTG + FBS group and 1.5% in women in the CTG + STAN (P = 0.338). More women in the CTG + STAN group delivered by operative vaginal delivery (25.6% vs 33.5%, P = 0.006). Significantly fewer women in the CTG + STAN group had three to five (28.8% vs 11.0%, P =  < 0.001) and six to ten fetal blood samples taken (3.4% vs 0.4%, P =  < 0.001).

CONCLUSION

CTG + STAN did not reduce the incidence of neonatal metabolic acidosis compared to CTG + FBS. CTG + STAN was, however, associated with an increased risk of operative vaginal delivery and a reduced use of FBS. If STAN is used for fetal surveillance, we recommend that it is combined with other methods, such as FBS, for confirmation of the need for operative delivery.

CLINICALTRIALS

gov ID: NCT01699646. Date of registration: October 4, 2012 (retrospectively registered). https://clinicaltrials.gov/ct2/show/NCT01699646?id=NCT01699646&draw=2&rank=1.

Changing Perspectives of Electronic Fetal Monitoring

The delivery of healthy babies is the primary goal of obstetric care. Many technologies have been developed to reduce both maternal and fetal risks for poor outcomes. For 50 years, electronic fetal monitoring (EFM) has been used extensively in labor attempting to prevent a large proportion of neonatal encephalopathy and cerebral palsy. However, even key opinion leaders admit that EFM has mostly failed to achieve this goal. We believe this situation emanates from a fundamental misunderstanding of differences between screening and diagnostic tests, considerable subjectivity and inter-observer variability in EFM interpretation, failure to address the pathophysiology of fetal compromise, and a tunnel vision focus. To address these suboptimal results, several iterations of increasingly sophisticated analyses have intended to improve the situation. We believe that part of the continuing problem is that the focus of EFM has been too narrow ignoring important contextual issues such as maternal, fetal, and obstetrical risk factors, and increased uterine contraction frequency. All of these can significantly impact the application of EFM to intrapartum care. We have recently developed a new clinical approach, the Fetal Reserve Index (FRI), contextualizing EFM interpretation. Our data suggest the FRI is capable of providing higher accuracy and earlier detection of emerging fetal compromise. Over time, artificial intelligence/machine learning approaches will likely improve measurements and interpretation of FHR characteristics and other relevant variables. Such future developments will allow us to develop more comprehensive models that increase the interpretability and utility of interfaces for clinical decision making during the intrapartum period.

Effectiveness of intrapartum fetal surveillance to improve maternal and neonatal outcomes: a systematic review and network meta-analysis

BACKGROUND:

Cesarean delivery is the most common surgical procedure worldwide. Intrapartum fetal surveillance is routinely offered to improve neonatal outcomes, but the effects of different methods on the risk of emergency cesarean deliveries remains uncertain. We conducted a systematic review and network meta-analysis to evaluate the effectiveness of different types of fetal surveillance.

METHODS:

We searched MEDLINE, Embase and CENTRAL until June 1, 2020, for randomized trials evaluating any intrapartum fetal surveillance method. We performed a network meta-analysis within a frequentist framework. We assessed the quality and network inconsistency of trials. We reported primarily on intrapartum emergency cesarean deliveries and other secondary maternal and neonatal outcomes using risk ratios (RRs) and 95% confidence intervals (CIs).

RESULTS:

We included 33 trials (118 863 patients) evaluating intermittent auscultation with Pinard stethoscope/handheld Doppler (IA), cardiotocography (CTG), computerized cardiotocography (cCTG), CTG with fetal scalp lactate (CTG-lactate), CTG with fetal scalp pH analysis (CTG-FBS), CTG with fetal pulse oximetry (FPO-CTG), CTG with fetal heart electrocardiogram (CTG-STAN) and their combinations. Intermittent auscultation reduced the risk of emergency cesarean deliveries compared with other types of surveillance (IA v. CTG: RR 0.83, 95% CI 0.72–0.97; IA v. CTG-FBS: RR 0.71, 95% CI 0.63–0.80; IA v.CTG-lactate: RR 0.77, 95% CI 0.64–0.92; IA v. FPO-CTG: RR 0.75, 95% CI 0.65–0.87; IA v.FPO-CTG-FBS: RR 0.81, 95% CI 0.67–0.99; cCTG-FBS v. IA: RR 1.21, 95% CI 1.04–1.42), except STAN-CTG-FBS (RR 1.17, 95% CI 0.98–1.40). There was a similar reduction observed for emergency cesarean deliveries for fetal distress. None of the evaluated methods was associated with a reduced risk of neonatal acidemia, neonatal unit admissions, Apgar scores or perinatal death.

INTERPRETATION:

Compared with other types of fetal surveillance, intermittent auscultation seems to reduce emergency cesarean deliveries in labour without increasing adverse neonatal and maternal outcomes.

Fetal electrocardiography ST-segment analysis for intrapartum monitoring: a critical appraisal of conflicting evidence and a way forward

BACKGROUND

In the past century, some areas of obstetric including intrapartum care have been slow to benefit from the dramatic advances in technology and medical care. Although fetal heart rate monitoring (cardiotocography) became available a half century ago, its interpretation often differs between institutions and countries, its diagnostic accuracy needs improvement, and a technology to help reduce the unnecessary obstetric interventions that have accompanied the cardiotocography is urgently needed.

STUDY DESIGN

During the second half of the 20th century, key findings in animal experiments captured the close relationship between myocardial glycogenolysis, myocardial workload, and ST changes, thus demonstrating that ST waveform analysis of the fetal electrocardiogram can provide information on oxygenation of the fetal myocardium and establishing the physiological basis for the use of electrocardiogram in intrapartum fetal surveillance.

RESULTS

Six randomized controlled trials, 10 meta-analyses, and more than 20 observational studies have evaluated the technology developed based on this principle. Nonetheless, despite this intensive assessment, differences in study protocols, inclusion criteria, enrollment rates, clinical guidelines, use of fetal blood sampling, and definitions of key outcome parameters, as well as inconsistencies in randomized controlled trial data handling and statistical methodology, have made this voluminous evidence difficult to interpret. Enormous resources spent on randomized controlled trials have failed to guarantee the generalizability of their results to other settings or their ability to reflect everyday clinical practice.

CONCLUSION

The latest meta-analysis used revised data from primary randomized controlled trials and data from the largest randomized controlled trials from the United States to demonstrate a significant reduction of metabolic acidosis rates by 36% (odds ratio, 0.64; 95% confidence interval, 0.46-0.88) and operative vaginal delivery rates by 8% (relative risk, 0.92; 95% confidence interval, 0.86-0.99), compared with cardiotocography alone.

Biases distorting priority setting

Modern health care faces an ever widening gap between technological possibilities and available resources. To handle this challenge we have constructed elaborate systems for health policy making and priority setting. Despite such systems many health care systems provide a wide range of documented low-value care while being unable to afford emerging high-value care. Accordingly, this article sets out asking why priority setting in health care has so poor outcomes while relevant systems are well developed and readily available. It starts to identify some rational and structural explanations for the discrepancy between theoretical efforts and practical outcomes in priority setting. However, even if these issues are addressed, practical priority setting may still not obtain its goals. This is because a wide range of irrational effects is hampering priority setting: biases. By using examples from the literature the article identifies and analyses a wide range of biases indicating how they can distort priority setting processes. Overuse, underuse, and overinvestment, as well as hampered disinvestment and undermined priority setting principles are but some of the identified implications. Moreover, while some biases are operating mainly on one level, many are active on the micro, meso and on the macro level. Identifying and analyzing biases affecting priority setting is the first, but crucial, step towards improving health policy making and priority setting in health care.

Significant reduction in umbilical artery metabolic acidosis after implementation of intrapartum ST waveform analysis of the fetal electrocardiogram

BACKGROUND

Although the evidence regarding the benefit of using ST waveform analysis of the fetal electrocardiogram is conflicting, ST waveform analysis is considered as adjunct to identify fetuses at risk for asphyxia in our center. Most randomized controlled trials and meta-analyses have not shown a significant decrease in umbilical metabolic acidosis, while some observational studies have shown a gradual decrease of this outcome over a longer period of time. Observational studies can give more insight into the effect of implementation of the ST technology in daily clinical practice.

OBJECTIVE

To evaluate the change in frequency of perinatal intervention and adverse neonatal outcome after the implementation of ST waveform analysis of the fetal electrocardiogram from 2000 to 2013.

STUDY DESIGN

This retrospective longitudinal study was conducted in a tertiary referral center. A total of 19,664 medium- and high-risk singleton pregnancies with fetuses in cephalic presentation, a gestational age of ≥36 weeks, and the intention to deliver vaginally were included. ST waveform analysis of the fetal electrocardiogram was implemented in the year 2000 and by 2010 all deliveries were monitored using this technology. Data were collected on the following perinatal outcomes: fetal blood sampling, mode of delivery, umbilical cord blood gases, Apgar scores, neonatal encephalopathy, and perinatal death. Longitudinal trend analysis was used to detect changes over time in all deliveries monitored by cardiotocography either alone or in adjunct to ST waveform analysis of the fetal electrocardiogram. Logistic regression was used to correct for possible confounders.

RESULTS

The umbilical artery metabolic acidosis rate declined from 2.5% (average rate of 2000 + 2001 + 2002) to 0.4% (average of 2011 + 2012 + 2013) (P < .001), which represents an 84% decrease. This decrease largely occurred between 2006 and 2008, during the Dutch randomized trial on fetal electrocardiogram ST waveform analysis. At this time, approximately 20% of deliveries were monitored using this method. Furthermore, there were significant reductions in fetal blood sampling rate (P < .001). Overall cesarean and vaginal instrumental deliveries decreased significantly (P < .001), but not for fetal distress. There were no changes in the Apgar scores. The incidence of neonatal encephalopathy was significantly lower in the second part of the study (odds ratio 0.39, 95% confidence interval 0.17-0.89).

CONCLUSION

There was an 84% decrease in the incidence of umbilical artery metabolic acidosis in all deliveries between 2000 and 2013. The neonatal encephalopathy rate, fetal blood sampling rate, and the total number of cesarean and vaginal instrumental deliveries also decreased.

Cardiotocography alone vs. cardiotocography with ST segment analysis for intrapartum fetal monitoring in women with late-term pregnancy. A randomized controlled trial

OBJECTIVES

Randomized studies have obtained conflicting results regarding the usefulness of fetal electrocardiographic (ECG) ST-segment analysis, possibly because these studies included non-homogeneous populations. We designed a study to determine whether this monitoring technique is potentially useful for populations at risk for fetal heart rate alterations during labor, i.e. groups of women who share late-term pregnancy as a risk factor.

STUDY DESIGN

This randomized clinical trial recruited women whose pregnancy had lasted more than 290 days. The participants were randomly assigned to continuous fetal cardiotocographic monitoring alone (CTG group) or with fetal ECG ST-segment analysis (ECG-F group). In the CTG group fetal heart rate was interpreted according to guidelines from the National Institute of Child Health and Human Development, whereas in the ECG-F group the tracings were interpreted according the original International Federation of Gynecology and Obstetrics (FIGO) guidelines. The primary outcome measure was neonatal outcome, evaluated as arterial blood pH in neonates after abdominal or vaginal operative delivery indicated because of nonreassuring fetal status.

RESULTS

A total of 237 women were randomized, of whom 200 were included in the final analysis (100 in each group). The rate of cesarean delivery was the same in both groups (26%), and the rate of operative delivery due to nonreassuring fetal status did not differ significantly (38% in the CTG group vs. 39% in the ECG-F group). Regarding neonatal outcomes, there was no significant difference between groups in neonatal pH (7.27 [7.23-7.29] and 7.25 [7.21-7.27]).

CONCLUSIONS

In a population comprising only late-term pregnancies, fetal ECG monitoring had no benefits for the mother or fetus. Additional studies are needed of protocols for using ST waveform analysis in selected population groups.

New FIGO and Swedish intrapartum cardiotocography classification systems incorporated in the fetal ECG ST analysis (STAN) interpretation algorithm: agreements and discrepancies in cardiotocography classification and evaluation of significant ST events

Introduction

The updated intrapartum cardiotocography (CTG) classification system by FIGO in 2015 (FIGO2015) and the FIGO2015‐approached classification by the Swedish Society of Obstetricians and Gynecologist in 2017 (SSOG2017) are not harmonized with the fetal ECG ST analysis (STAN) algorithm from 2007 (STAN2007). The study aimed to reveal homogeneity and agreement between the systems in classifying CTG and ST events, and relate them to maternal and perinatal outcomes.

Material and methods

Among CTG traces with ST events, 100 traces originally classified as normal, 100 as suspicious and 100 as pathological were randomly selected from a STAN database and classified by two experts in consensus. Homogeneity and agreement statistics between the CTG classifications were performed. Maternal and perinatal outcomes were evaluated in cases with clinically hidden ST data (n = 151). A two‐tailed p < 0.05 was regarded as significant.

Results

For CTG classes, the heterogeneity was significant between the old and new systems, and agreements were moderate to strong (proportion of agreement, kappa index 0.70–0.86). Between the new classifications, heterogeneity was significant and agreements strong (0.90, 0.92). For significant ST events, heterogeneities were significant and agreements moderate to almost perfect (STAN2007 vs. FIGO2015 0.86, 0.72; STAN2007 vs. SSOG2017 0.92, 0.84; FIGO2015 vs. SSOG2017 0.94, 0.87). Significant ST events occurred more often combined with STAN2007 than with FIGO2015 classification, but not with SSOG2017; correct identification of adverse outcomes was not significantly different between the systems.

Conclusion

There are discrepancies in the classification of CTG patterns and significant ST events between the old and new systems. The clinical relevance of the findings remains to be shown.

Acceptance of a new non-invasive fetal monitoring system and attitude for telemedicine approaches in obstetrics: a case-control study

PURPOSE

Reduction of maternal morbidity and mortality is a major worldwide objective anchored in the millennium goals of the United Nations. To improve fetal and maternal care, a constant attempt to discover groundbreaking technologies is ongoing. One approach is the enhancement of non-invasive fetal ECG devices. Most importantly, acceptance of new technologies by pregnant women is a prerequisite for successful implementation.

METHODS

This questionnaire-based study conducted at the University Hospital Heidelberg, Germany between May and June 2017 evaluates pregnant women's attitudes towards a new device for fetal ECG monitoring and its potential home usage. The study population was questioned after exposure to the Parides/Atlantis prototype (Nemo Healthcare, Veldhoven, The Netherlands), whereas the maternal and gestational age-matched control group was left to envision telemedical topics.

RESULTS

The prototype and its potential usage in a clinical and telemedical setting was highly accepted, and its comfort and appearance satisfied participants. Its use caused significantly improved telemedical understanding as envision increased (p = 0.0015). Implementation and integration of telemedical devices into antenatal care was significantly preferred by the study group (p = 0.0011), though participants desire more specific features for their personal use. Optional home-based self-monitoring to reduce scheduled doctoral visits (p = 0.0004) as well as self-assessment prior to self-initiated, unscheduled consultation (p < 0.0001) could be affected positively by such a device. Furthermore, it could reduce face-to-face interaction with the care provider (p = 0.0163).

CONCLUSIONS

The positive feedback on remote self-monitoring might open options for a more "patient as partners" oriented prenatal care in the future. Safety and reliability remain a major issue. More comprehensive studies with new technologies are needed to diligently ensure quality of care. Finally, results for new technologies must be communicated to pregnant women for their acceptance and usage of new devices.

Waveform analysis of the fetal ECG in labor in patients with intrahepatic cholestasis of pregnancy

AIM

Intrahepatic cholestasis of pregnancy (ICP) is reported to be associated with an increased risk of sudden fetal death. The possible mechanism is thought to be cardiac arrhythmia. Prolonged QT interval of the electrocardiogram (ECG) is associated with arrhytmogenic events. The aim of the study was to compare the fetal ECG QT interval during labor in pregnancies complicated with ICP to healthy controls.

METHODS

The fetal ECG and QT interval was reviewed retrospectively. The intrapartum QT interval was measured in 61 fetuses born to mothers with ICP and in a control group of similar size. The corrected QT interval (QTc) was calculated using Bazett's formula: QT/√RR. The occurrence of ST segment depression was also included in the analysis.

RESULTS

The groups were similar regarding to maternal age, parity, BMI, gestational age and smoking habits. The rate of labor induction was significantly higher in ICP patients (P < 0.001). The QTc at the beginning and the end of recording was analyzed and there were no significant differences in these values between the ICP patients and healthy controls (P = 0.467). Most ICP patients used ursodeoxycholic acid (UDCA) for mediation. We analyzed separately patients who had elevated liver enzymes before labor. No significant differences in the QTc were noted in these patients either. Nor were there any significant ST depressions in ICP patients.

CONCLUSIONS

The etiology of adverse perinatal outcome and even sudden fetal death in ICP is still controversial. No differences in QTc intervals and ST waveforms during labor were found in our study material.

Comparison of neonatal outcomes between category-1 and non-category-1 Primary Emergency Cesarean Section: A retrospective record review in a tertiary care hospital

OBJECTIVE

To compare neonatal outcomes between Category-1 and Non-Category-1 Primary Emergency Cesarean Section.

METHODS

This was a retrospective analysis, conducted at Aga Khan University Hospital Karachi from January 1st 2016 till December 31st 2016. Non-probability purposive sampling technique was used. A sample size of 375 patients who had primary Emergency Caesarean Section (Em-CS) was identified by keeping CS rate of 41.5% and 5% bond on error. Data was collected from labor ward, operating theatre and neonatal ward records by using structured questionnaire.

RESULTS

In the current study, out of 375 participants who underwent primary Em-CS; majority (89.3%) were booked cases. Two-hundred-eighty-two (75.2%) were primiparous women. Two hundred and thirty (61.3%) were at term and 145(38.7%) were preterm. The main indication among Category-1 CS was fetal distress (15.7%). For Non-Category-1 CS, non-progress of labour (45.1%) was the leading cause of abdominal delivery. Except for APGAR score at one minute (p value = 0.048), no other variables were statistically significant when neonatal outcomes were compared among Category-1 and Non-Category-1 CS.

CONCLUSION

In this study, fetal distress and non-progress of labor were the main indications for Category-1 and Non-Category-1 CS respectively. We did not find statistically significant association between indications of Em CS and neonatal outcomes. However further prospective studies are required to confirm this association.

The importance of the learning process in ST analysis interpretation and its impact in improving clinical and neonatal outcomes

BACKGROUND

Intrapartum fetal heart rate monitoring was introduced with the goal to reduce fetal hypoxia and deaths. However, continuous fetal heart rate monitoring has been shown to have a high sensitivity but also a high false-positive rate. To improve specificity, adjunctive technologies have been developed to identify fetuses at risk for intrapartum asphyxia. Intensive research on the value of ST-segment analysis of the fetal electrocardiogram as an adjunct to standard electronic fetal monitoring in lowering the rates of fetal metabolic acidosis and operative deliveries has been ongoing. The conflicting results in randomized and observational studies may partly be due to differences in study design.

OBJECTIVE

This study aims to determine the significance of the learning process for the introduction of ST analysis into clinical practice and its impact on initial and subsequent obstetric outcomes.

STUDY DESIGN

This was a prospective observational study with the primary objective to evaluate the importance of the learning period on the rates of metabolic acidosis and operative deliveries after the implementation of ST analysis. The study was conducted at the Turku University Hospital, Turku, Finland, with 3400-4200 annual deliveries. The whole study population consisted of all 42,146 deliveries during the study period 2001 through 2011. The ST analysis usage rate was 18%. The data were collected prospectively from labors monitored with ST analysis as an adjunct to conventional intrapartum fetal heart rate monitoring. Primary endpoints were the rates of metabolic acidosis (cord artery pH <7.05 and an extracellular fluid compartment base deficit >12.0 mmol/L), fetal scalp blood sampling, and operative deliveries. Comparisons of these outcomes were made between the initiation period (the first 2 years) and the subsequent usage period (the next 9 years).

RESULTS

In the whole study population the prevalence of cord pH <7.05 decreased from 1.5-0.81% (relative risk, 0.54; 95% confidence interval, 0.43-0.67), the rate of cesarean deliveries from 17.2-14.1% (relative risk, 0.82; 95% confidence interval, 0.89-0.97), and the rate of fetal scalp blood sampling from 1.75-0.82% (relative risk, 0.47; 95% confidence interval, 0.38-0.58) when the 2 study periods were compared. In the ST analysis group, the frequency of cord metabolic acidosis rate was reduced from 1.0-0.25% (relative risk, 0.33; 95% confidence interval, 0.15-0.72).

CONCLUSION

We provide evidence that the results improve over time and there is a learning curve in the introduction of the ST analysis method. This was demonstrated by the lower rates of metabolic acidosis and operative deliveries after the initial implementation period.

A pilot exploratory investigation on pregnant women's views regarding STan fetal monitoring technology

BACKGROUND

Women's views are critical for informing the planning and delivery of maternity care services. ST segment analysis (STan) is a promising method to more accurately detect when unborn babies are at risk of brain damage or death during labour that is being trialled for the first time in Australia. This is the first study to examine women's views about STan monitoring in this context.

METHODS

Semi-structured interviews were conducted with pregnant women recruited across a range of clinical locations at the study hospital. The interviews included hypothetical scenarios to assess women's prospective views about STan monitoring (as an adjunct to cardiotocography, (CTG)) compared to the existing fetal monitoring method of CTG alone. This article describes findings from an inductive and descriptive thematic analysis.

RESULTS

Most women preferred the existing fetal monitoring method compared to STan monitoring; women's decision-making was multifaceted. Analysis yielded four themes relating to women's views towards fetal monitoring in labour: a) risk and labour b) mobility in labour c) autonomy and choice in labour d) trust in maternity care providers.

CONCLUSIONS

Findings suggest that women's views towards CTG and STan monitoring are multifaceted, and appear to be influenced by individual labour preferences and the information being received and understood. This underlies the importance of clear communication between maternity care providers and women about technology use in intrapartum care. This research is now being used to inform the implementation of the first properly powered Australian randomised trial comparing STan and CTG monitoring.

Does ST analysis have a place in electronic fetal monitoring?

Intrapartum cardiotocography (CTG) has a high false-positive rate. This has contributed to the rapid increase in obstetric interventions without a strong improvement in perinatal outcomes. We explore the role of ST analysis (STAN®) as an adjunct to CTG in identifying fetal asphyxia during labor. We conclude that STAN® reduces the rate of fetal blood sampling and instrumental vaginal deliveries, and has the potential to reduce the number of Australian operative interventions without compromising neonatal outcome.

Electrocardiogram ST Analysis During Labor: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To compare the effectiveness of cardiotocography plus ST analysis with cardiotocography alone during labor.

DATA SOURCES

Randomized controlled trials were identified by searching electronic databases.

METHODS OF STUDY SELECTION

We included all randomized controlled trials comparing intrapartum fetal monitoring with cardiotocography plus ST analysis with cardiotocography alone. The primary outcome (ie, perinatal composite outcome) was a composite of intrapartum fetal death, neonatal death, Apgar score 3 or less at 5 minutes, neonatal seizure, metabolic acidosis (defined as umbilical arterial pH 7.05 or less, and extracellular fluid base deficit 12 mmol/L or greater), intubation for ventilation at delivery, or neonatal encephalopathy.

TABULATION, INTEGRATION, AND RESULTS

Six randomized controlled trials, which included 26,529 laboring singletons with cephalic presentation at term, were analyzed. Compared with women who were randomized to cardiotocography, those who were randomized to ST analysis and cardiotocography had a similar incidence of perinatal composite outcome (1.5% compared with 1.6%; relative risk [RR] 0.90, 95% confidence interval [CI] 0.74-1.10; five studies), neonatal metabolic acidosis (0.5% compared with 0.7%; RR 0.74, 95% CI 0.54-1.02; five studies), admission to the neonatal intensive care unit (5.4% compared with 5.5%; RR 0.99, 95% CI 0.90-1.10; six studies), perinatal death (0.1% compared with 0.1%; RR 1.71, 95% CI 0.67-4.33; six studies), neonatal encephalopathy (0.1% compared with 0.2%; RR 0.62, 95% CI 0.25-1.52; six studies), cesarean delivery (13.8% compared with 14.0%; RR 0.96, 95% CI 0.85-1.08; six studies), and operative delivery (either cesarean or operative vaginal delivery) (23.9% compared with 25.1%; RR 0.93, 95% CI 0.86-1.01; six studies).

CONCLUSION

The use of ST analysis during labor as an adjunct to the standard cardiotocography does not improve perinatal outcomes or decrease cesarean delivery.

Fetal electrocardiogram (ECG) for fetal monitoring during labour

BACKGROUND

Hypoxaemia during labour can alter the shape of the fetal electrocardiogram (ECG) waveform, notably the relation of the PR to RR intervals, and elevation or depression of the ST segment. Technical systems have therefore been developed to monitor the fetal ECG during labour as an adjunct to continuous electronic fetal heart rate monitoring with the aim of improving fetal outcome and minimising unnecessary obstetric interference.

OBJECTIVES

To compare the effects of analysis of fetal ECG waveforms during labour with alternative methods of fetal monitoring.

SEARCH METHODS

The Cochrane Pregnancy and Childbirth Group's Trials Register (latest search 23 September 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised trials comparing fetal ECG waveform analysis with alternative methods of fetal monitoring during labour.

DATA COLLECTION AND ANALYSIS

One review author independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. One review author assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

Seven trials (27,403 women) were included: six trials of ST waveform analysis (26,446 women) and one trial of PR interval analysis (957 women). The trials were generally at low risk of bias for most domains and the quality of evidence for ST waveform analysis trials was graded moderate to high. In comparison to continuous electronic fetal heart rate monitoring alone, the use of adjunctive ST waveform analysis made no obvious difference to primary outcomes: births by caesarean section (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.96 to 1.08; six trials, 26,446 women; high quality evidence); the number of babies with severe metabolic acidosis at birth (cord arterial pH less than 7.05 and base deficit greater than 12 mmol/L) (average RR 0.72, 95% CI 0.43 to 1.20; six trials, 25,682 babies; moderate quality evidence); or babies with neonatal encephalopathy (RR 0.61, 95% CI 0.30 to 1.22; six trials, 26,410 babies; high quality evidence). There were, however, on average fewer fetal scalp samples taken during labour (average RR 0.61, 95% CI 0.41 to 0.91; four trials, 9671 babies; high quality evidence) although the findings were heterogeneous and there were no data from the largest trial (from the USA). There were marginally fewer operative vaginal births (RR 0.92, 95% CI 0.86 to 0.99; six trials, 26,446 women); but no obvious difference in the number of babies with low Apgar scores at five minutes or babies requiring neonatal intubation, or babies requiring admission to the special care unit (RR 0.96, 95% CI 0.89 to 1.04, six trials, 26,410 babies; high quality evidence). There was little evidence that monitoring by PR interval analysis conveyed any benefit of any sort.

AUTHORS' CONCLUSIONS

The modest benefits of fewer fetal scalp samplings during labour (in settings in which this procedure is performed) and fewer instrumental vaginal births have to be considered against the disadvantages of needing to use an internal scalp electrode, after membrane rupture, for ECG waveform recordings. We found little strong evidence that ST waveform analysis had an effect on the primary outcome measures in this systematic review.There was a lack of evidence showing that PR interval analysis improved any outcomes; and a larger future trial may possibly demonstrate beneficial effects.There is little information about the value of fetal ECG waveform monitoring in preterm fetuses in labour. Information about long-term development of the babies included in the trials would be valuable.

Continuous cardiotocography during labour: Analysis, classification and management

The use of continuous intrapartum electronic fetal heart rate monitoring (EFM) using a cardiotocograph (CTG) was developed to enable obstetricians and midwives to analyse the changes of fetal heart rate during labour so as to institute timely intervention to avoid intrapartum hypoxic-ischaemic injury. Although CTG was initially developed as a screening tool to predict fetal hypoxia, its positive predictive value for intrapartum fetal hypoxia is approximately only 30%. Even though different international classifications have been developed with the aim of defining combinations of features that help predict intrapartum fetal hypoxia, the false-positive rate of the CTG is high (60%). Moreover, there has not been a demonstrable improvement in the rate of cerebral palsy or perinatal deaths since the introduction of CTG into clinical practice approximately 45 years ago. However, there has been a significant increase in intrapartum caesarean section and operative vaginal delivery rates. Unfortunately, existing guidelines employ the visual interpretation of CTG based on 'pattern recognition', which is fraught with inter- and intra-observer variability. Therefore, clinicians need to understand the physiology behind fetal heart rate changes and to respond to them accordingly, instead of purely relying on guidelines for management. It is very likely that such a 'physiology-based' approach would reduce unnecessary operative interventions and improve perinatal outcomes whilst reducing the need for 'additional tests' of fetal well-being.

A critical appraisal of the evidence for using cardiotocography plus ECG ST interval analysis for fetal surveillance in labor. Part I: the randomized controlled trials

We reappraised the five randomized controlled trials that compared cardiotocography plus ECG ST interval analysis (CTG+ST) vs. cardiotocography. The numbers enrolled ranged from 5681 (Dutch randomized controlled trial) to 799 (French randomized controlled trial). The Swedish randomized controlled trial (n = 5049) was the only trial adequately powered to show a difference in metabolic acidosis, and the Plymouth randomized controlled trial (n = 2434) was only powered to show a difference in operative delivery for fetal distress. There were considerable differences in study design: the French randomized controlled trial used different inclusion criteria, and the Finnish randomized controlled trial (n = 1483) used a different metabolic acidosis definition. In the CTG+ST study arms, the larger Plymouth, Swedish and Dutch trials showed lower operative delivery and metabolic acidosis rates, whereas the smaller Finnish and French trials showed minor differences in operative delivery and higher metabolic acidosis rates. We conclude that the differences in outcomes are likely due to the considerable differences in study design and size. This will enhance heterogeneity effects in any subsequent meta-analysis.