Cardiotocography and medicolegal issues

Non-Invasive Fetal Electrocardiogram Monitoring Techniques: Potential and Future Research Opportunities in Smart Textiles

During the pregnancy, fetal electrocardiogram (FECG) is deployed to analyze fetal heart rate (FHR) of the fetus to indicate the growth and health of the fetus to determine any abnormalities and prevent diseases. The fetal electrocardiogram monitoring can be carried out either invasively by placing the electrodes on the scalp of the fetus, involving the skin penetration and the risk of infection, or non-invasively by recording the fetal heart rate signal from the mother’s abdomen through a placement of electrodes deploying portable, wearable devices. Non-invasive fetal electrocardiogram (NIFECG) is an evolving technology in fetal surveillance because of the comfort to the pregnant women and being achieved remotely, specifically in the unprecedented circumstances such as pandemic or COVID-19. Textiles have been at the heart of human technological progress for thousands of years, with textile developments closely tied to key inventions that have shaped societies. The relatively recent invention of smart textiles is set to push boundaries again and has already opened the potential for garments relevant to medicine, and health monitoring. This paper aims to discuss the different technologies and methods used in non-invasive fetal electrocardiogram (NIFECG) monitoring as well as the potential and future research directions of NIFECG in the smart textiles area.

Threshold of metabolic acidosis associated with newborn cerebral palsy: medical legal implications

Obstetricians and gynecologists belong to 1 of the medical specialties with the highest rate of litigation claims. Among birth injury cases, those cases with cerebral palsy outcomes account for litigation settlements or judgments often in the millions of dollars. In cases of potential perinatal asphyxia, a threshold level of metabolic acidosis (base deficit ≥12 mmol/L) is necessary to attribute neonatal encephalopathy to an intrapartum hypoxic event. With increasing duration or severity of a hypoxic stress resulting in metabolic acidosis, newborn infant umbilical artery base deficit increases. It may be alleged that, as base deficit levels increase beyond 12 mmol/L, there is an increased likelihood and severity of cerebral palsy. As a corollary, it may be claimed that an earlier delivery (by minutes) would reduce the base deficit and prevent or reduce the severity of cerebral palsy. This issue is of relevance to obstetricians as defendants, because retrospective "expert" analysis of cases may suggest that optimal management decisions would have resulted in an earlier delivery. In addressing the association of metabolic acidosis and cerebral palsy, base deficit should be measured as the extracellular component (base deficit_{extracellular fluid}) rather than the commonly used base deficit_blood. Studies suggest that, beyond the base deficit threshold of 12 mmol/L, the incidence and severity of cerebral palsy does not significantly increase (until ≥20 mmol/L), although the risk of neonatal death rises markedly. Thus, among most infants with hypoxia-associated neonatal encephalopathy, the occurrence of cerebral palsy is unlikely to be impacted by delivery time variation of few minutes, and this argument should not serve as the basis for medical legal claims.

Comparative Effectiveness of ICA and PCA in Extraction of Fetal ECG From Abdominal Signals: Toward Non-invasive Fetal Monitoring

Non-adaptive signal processing methods have been successfully applied to extract fetal electrocardiograms (fECGs) from maternal abdominal electrocardiograms (aECGs); and initial tests to evaluate the efficacy of these methods have been carried out by using synthetic data. Nevertheless, performance evaluation of such methods using real data is a much more challenging task and has neither been fully undertaken nor reported in the literature. Therefore, in this investigation, we aimed to compare the effectiveness of two popular non-adaptive methods (the ICA and PCA) to explore the non-invasive (NI) extraction (separation) of fECGs, also known as NI-fECGs from aECGs. The performance of these well-known methods was enhanced by an adaptive algorithm, compensating amplitude difference and time shift between the estimated components. We used real signals compiled in 12 recordings (real01-real12). Five of the recordings were from the publicly available database (PhysioNet-Abdominal and Direct Fetal Electrocardiogram Database), which included data recorded by multiple abdominal electrodes. Seven more recordings were acquired by measurements performed at the Institute of Medical Technology and Equipment, Zabrze, Poland. Therefore, in total we used 60 min of data (i.e., around 88,000 R waves) for our experiments. This dataset covers different gestational ages, fetal positions, fetal positions, maternal body mass indices (BMI), etc. Such a unique heterogeneous dataset of sufficient length combining continuous Fetal Scalp Electrode (FSE) acquired and abdominal ECG recordings allows for robust testing of the applied ICA and PCA methods. The performance of these signal separation methods was then comprehensively evaluated by comparing the fetal Heart Rate (fHR) values determined from the extracted fECGs with those calculated from the fECG signals recorded directly by means of a reference FSE. Additionally, we tested the possibility of non-invasive ST analysis (NI-STAN) by determining the T/QRS ratio. Our results demonstrated that even though these advanced signal processing methods are suitable for the non-invasive estimation and monitoring of the fHR information from maternal aECG signals, their utility for further morphological analysis of the extracted fECG signals remains questionable and warrants further work.

The myths and physiology surrounding intrapartum decelerations: the critical role of the peripheral chemoreflex

A distinctive pattern of recurrent rapid falls in fetal heart rate, called decelerations, are commonly associated with uterine contractions during labour. These brief decelerations are mediated by vagal activation. The reflex triggering this vagal response has been variably attributed to a mechanoreceptor response to fetal head compression, to baroreflex activation following increased blood pressure during umbilical cord compression, and/or a Bezold-Jarisch reflex response to reduced venous return from the placenta. Although these complex explanations are still widespread today, there is no consistent evidence that they are common during labour. Instead, the only mechanism that has been systematically investigated, proven to be reliably active during labour and, crucially, capable of producing rapid decelerations is the peripheral chemoreflex. The peripheral chemoreflex is triggered by transient periods of asphyxia that are a normal phenomenon associated with all uterine contractions. This should not cause concern as the healthy fetus has a remarkable ability to adapt to these repeated but short periods of asphyxia. This means that the healthy fetus is typically not at risk of hypotension and injury during uncomplicated labour even during repeated brief decelerations. The physiologically incorrect theories surrounding decelerations that ignore the natural occurrence of repeated asphyxia probably gained widespread support to help explain why many babies are born healthy despite repeated decelerations during labour. We propose that a unified and physiological understanding of intrapartum decelerations that accepts the true nature of labour is critical to improve interpretation of intrapartum fetal heart rate patterns.

Intra- and interobserver agreement among obstetric experts in court regarding the review of abnormal fetal heart rate tracings and obstetrical management

OBJECTIVE

The objective of the study was to evaluate the intra- and interobserver agreement among obstetric experts in court regarding the retrospective review of abnormal fetal heart rate tracings and obstetrical management of patients with abnormal fetal heart rate during labor.

STUDY DESIGN

A total of 22 French obstetric experts in court reviewed 30 cases of term deliveries of singleton pregnancies diagnosed with at least 1 hour of abnormal fetal heart rate, including 10 cases with adverse neonatal outcome. The experts reviewed all cases twice within a 3-month interval, with the first review being blinded to neonatal outcome. For each case reviewed, the experts were provided with the obstetric data and copies of the complete fetal heart rate recording and the partogram. The experts were asked to classify the abnormal fetal heart rate tracing and to express whether they agreed with the obstetrical management performed. When they disagreed, the experts were asked whether they concluded that an error had been made and whether they considered the obstetrical management as the cause of cerebral palsy in children if any.

RESULTS

Compared with blinded review, the experts were significantly more likely to agree with the obstetric management performed (P < .001) and with the mode of delivery (P < .001) when informed about the neonatal outcome and were less likely to conclude that an error had been made (P < .001) or to establish a link with potential cerebral palsy (P = .003). The experts' intraobserver agreement for the review of abnormal fetal heart rate tracing and obstetrical management were both mediocre (kappa = 0.46-0.51 and kappa = 0.48-0.53, respectively). The interobserver agreement for the review of abnormal fetal heart rate tracing was low and was not improved by knowledge of the neonatal outcome (kappa = 0.11-0.18). The interobserver agreement for the interpretation of obstetrical management was also low (kappa = 0.08-0.19) but appeared to be improved by knowledge of the neonatal outcome (kappa = 0.15-0.32).

CONCLUSION

The intra- and interobserver agreement among obstetric experts in court for the review of abnormal fetal heart rate tracing and the appropriateness of obstetrical care is poor, suggesting a lack of objectivity of obstetrical expertise as currently performed in court.

Computer analysis of foetal monitoring signals

Five systems for computer analysis of foetal monitoring signals are currently available, incorporating the evaluation of cardiotocographic (CTG) or combined CTG with electrocardiographic ST data. All systems have been integrated with central monitoring stations, allowing the simultaneous monitoring of several tracings on the same computer screen in multiple hospital locations. Computer analysis elicits real-time visual and sound alerts for health care professionals when abnormal patterns are detected, with the aim of prompting a re-evaluation and subsequent clinical action, if considered necessary. Comparison between the CTG analyses provided by the computer and clinical experts has been carried out in all systems, and in three of them, the accuracy of computer alerts in predicting newborn outcomes was evaluated. Comparisons between these studies are hampered by the differences in selection criteria and outcomes. Two of these systems have just completed multicentre randomised clinical trials comparing them with conventional CTG monitoring, and their results are awaited shortly. For the time being, there is limited evidence regarding the impact of computer analysis of foetal monitoring signals on perinatal indicators and on health care professionals' behaviour.

Expert review--identification of intra-partum fetal compromise

Whilst most cases of cerebral palsy occur as a consequence of an ante-natal insult, a significant proportion, particularly in the term fetus, are attributable to intra-partum hypoxia. Intra-partum monitoring using continuous fetal heart rate assessment has led to an increased incidence of operative delivery without a concurrent reduction in the incidence of cerebral palsy. Despite this, birth asphyxia remains the strongest and most consistent risk factor for cerebral palsy in term infants. This review evaluates current intra-partum monitoring techniques as well as alternative approaches aimed at better identification of the fetus at risk of compromise in labour.

Being safe practitioners and safe mothers: a critical ethnography of continuity of care midwifery in Australia

OBJECTIVE

To examine how midwives and women within a continuity of care midwifery programme in Australia conceptualised childbirth risk and the influences of these conceptualisations on women's choices and midwives' practice.

DESIGN AND SETTING

A critical ethnography within a community-based continuity of midwifery care programme, including semi-structured interviews and the observation of sequential antenatal appointments.

PARTICIPANTS

Eight midwives, an obstetrician and 17 women.

FINDINGS

The midwives assumed a risk-negotiator role in order to mediate relationships between women and hospital-based maternity staff. The role of risk-negotiator relied profoundly on the trust engendered in their relationships with women. Trust within the mother-midwife relationship furthermore acted as a catalyst for complex processes of identity work which, in turn, allowed midwives to manipulate existing obstetric risk hierarchies and effectively re-order risk conceptualisations. In establishing and maintaining identities of 'safe practitioner' and 'safe mother', greater scope for the negotiation of normal within a context of obstetric risk was achieved.

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

The effects of obstetric risk practices can be mitigated when trust within the mother-midwife relationship acts as a catalyst for identity work and supports the midwife's role as a risk-negotiator. The achievement of mutual identity-work through the midwives' role as risk-negotiator can contribute to improved outcomes for women receiving continuity of care. However, midwives needed to perform the role of risk-negotiator while simultaneously negotiating their professional credibility in a setting that construed their practice as risky.

Impact of the introduction of fetal central monitoring on hospital expenses with cardiotocographic paper

Digital storage of cardiotocographic (CTG) tracings by fetal central monitoring systems (fCMS) obviates the need for printing, or alternatively, the tracings can be printed in regular paper instead of CTG thermal paper. We aimed at evaluating the impact of the introduction of the Omniview-SisPorto(®) system on CTG paper costs in a large university hospital. After introduction of the fCMS, there was an 87% reduction in median annual expenses with CTG paper in the labour ward (p = 0.011) and a 78% decrease in the prenatal clinic (p = 0.017), despite a more than 40% increase in the median number of observed women. Routine use of fCMS may provide an important reduction in hospital expenses associated with the use of thermal CTG paper, thus reducing the investment made in their acquisition and maintenance.

Monitoring uterine activity during labor: a comparison of 3 methods

OBJECTIVE

Tocodynamometry (Toco; strain gauge technology) provides contraction frequency and approximate duration of labor contractions but suffers frequent signal dropout, necessitating repositioning by a nurse, and may fail in obese patients. The alternative invasive intrauterine pressure catheter (IUPC) is more reliable and adds contraction pressure information but requires ruptured membranes and introduces small risks of infection and abruption. Electrohysterography (EHG) reports the electrical activity of the uterus through electrodes placed on the maternal abdomen. This study compared all 3 methods of contraction detection simultaneously in laboring women.

STUDY DESIGN

Upon consent, laboring women were monitored simultaneously with Toco, EHG, and IUPC. Contraction curves were generated in real-time for the EHG, and all 3 curves were stored electronically. A contraction detection algorithm was used to compare frequency and timing between methods. Seventy-three subjects were enrolled in the study; 14 were excluded due to hardware failure of 1 or more of the devices (n = 12) or inadequate data collection duration (n = 2).

RESULTS

In comparison with the gold-standard IUPC, EHG performed significantly better than Toco with regard to the Contractions Consistency Index (CCI). The mean CCI for EHG was 0.88 ± 0.17 compared with 0.69 ± 0.27 for Toco (P < .0001). In contrast to Toco, EHG was not significantly affected by obesity.

CONCLUSION

Toco does not correlate well with the gold-standard IUPC and fails more frequently in obese patients. EHG provides a reliable noninvasive alternative, regardless of body habitus.

Intrapartum fetal asphyxia: study of umbilical cord blood lactate in relation to fetal heart rate patterns

PURPOSES

To correlate between umbilical artery cord blood lactate and acid-base status with intrapartum fetal heart rate monitoring, and to measure the reliability of umbilical cord blood lactate for prediction of early neonatal outcome.

METHODS

Sixty-six participants with intrapartum abnormal fetal heart rate monitoring and 60 participants with normal intrapartum recordings were recruited. The abnormal recordings included late onset, atypical variable and simple variable decelerations. After delivery, the arterial cord blood lactate, pH, actual base excess (ABE), and Apgar score were measured in all participants.

RESULTS

There was significant inverse correlation between cord lactate and pH and ABE in all participants (correlation coefficient = -0.7, p < 0.0001). The cord lactate was significantly higher in the late onset and atypical variable decelerations groups compared to control (p < 0.0001). There was no significant correlation between the Apgar score and blood lactate in all groups; however, the sensitivity and specificity of cord lactate to predict low score at 5 min were higher in comparison to cord pH.

CONCLUSIONS

Umbilical cord blood lactate is a reliable marker for intrapartum fetal asphyxia compared to cord acid-base status with better prediction for newborns with low Apgar score.

[Cerebral palsy and perinatal asphyxia (II--Medicolegal implications and prevention)]

Obstetric litigation is a growing problem in developed countries and its escalating cost together with increasing medical insurance premiums is a major concern for maternity service providers, leading to obstetric practice cessation by many practitioners. Fifty-four to 74 % of claims are based on cardiotocographic (CTG) abnormalities and their interpretation followed by inappropriate or delayed reactions. A critical analysis is performed about the nine criteria identified by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics in their task force on Neonatal Encephalopathy and Cerebral Palsy: four essential criteria defining neonatal asphyxia and five other suggesting an acute intrapartum event sufficient to cause cerebral palsy in term newborns. The importance of placental histologic examination is emphasized in order to confirm sudden catastrophic events occurring before or during labor or to detect occult thrombotic processes affecting the fetal circulation, patterns of decreased placenta reserve and adaptative responses to chronic hypoxia. It may also exclude intrapartum hypoxia by revealing some histologic patterns typical of acute chorioamnionitis and fetal inflammatory response or compatible with metabolic diseases. Magnetic resonance imaging (MRI) of the infant's damaged brain is very contributive to elucidate the mechanism and timing of asphyxia in conjunction with the clinical picture, by locating cerebral injuries predominantly in white or grey matter. Intrapartum asphyxia is sometimes preventable by delivering weak fetuses by cesarean sections before birth, by avoiding some "sentinel" events, and essentially by responding appropriately to CTG anomalies and performing an efficient neonatal resuscitation. During litigation procedures, it is necessary to have access to a readable CTG, a well-documented partogram, a complete analysis of umbilical cord gases, a placental pathology and an extensive clinical work-up of the newborn infant including cerebral MRI. Malpractice litigation in obstetric care can be reduced by permanent CTG education, respect of national CTG guidelines, use of adjuncts such as fetal blood sampling for pH or lactates, regular review of adverse events in Clinical Risk Management (CRM) groups and periodic audits about low arterial cord pH in newborns, admission to neonatal unit, the need for assisted ventilation and the decision-to-delivery interval for emergency operative deliveries. Considering the fast occurrence of fetal cerebral hypoxic injuries, and thus despite an adequate management, many intrapartum asphyxias will not be preventable. Conversely, well-documented hypoxic-ischemic brain insults during the antenatal period do not automatically exclude intrapartum suboptimal obstetric care.

Do expert patients get better treatment than others? Agency discrimination and statistical discrimination in obstetrics

We address models that can explain why expert patients (obstetricians, midwives and doctors) are treated better than non-experts (mainly non-medical training). Models of statistical discrimination show that benevolent doctors treat expert patients better, since experts are better at communicating with the doctor. Agency theory suggests that doctors have an incentive to limit hospital costs by distorting information to non-expert patients, but not to expert patients. The hypotheses were tested on a large set of data, which contained information about the highest education of the parents, and detailed medical information about all births in Norway during the period 1967-2005 (Medical Birth Registry). The empirical analyses show that expert parents have a higher rate of Caesarean section than non-expert parents. The educational disparities were considerable 40 years ago, but have become markedly less over time. The analyses provide support for statistical discrimination theory, though agency theory cannot be totally excluded.

The quality of intrapartum uterine activity monitoring

AIMS

To determine the quality of intrapartum uterine activity (UA) monitoring in daily practice during the first and second stage of labor. The total duration of inadequate UA monitoring is quantified in relation to the technique applied: external or internal.

METHODS

One hundred and ninety-two UA recordings, collected from 1 April 2006 untill 1 October 2006 from consecutive deliveries at the Vrije Universiteit Medical Center in Amsterdam, were analyzed. Included recordings were from singleton, spontaneous, vaginal deliveries. The last two hours of the first stage and the complete second stage had to be monitored. Internal and external UA recordings were judged by their quality: adequate, a recognizable and reliable UA pattern during the complete registration, or inadequate. Recordings labeled as inadequate were divided into two groups: absence of UA recording (non recognizable) or inadequate calibration (unreliable). Statistical analyses were performed with the Mann-Whitney U-test and the Wilcoxon signed ranks test.

RESULTS

The percentages of adequate UA recordings in the first stage of labor were much higher for the internal than the external mode. Only 2% of the external recordings were of good quality vs. 40% of the internal recordings. In the second stage, percentages of adequate UA recordings were nearly equal, approximately 30%. Inadequate external registrations were characterized by almost 30% of the time absent UA monitoring, whereas with inadequate internal registrations the primary problem was correct calibration.

CONCLUSION

Intrapartum UA monitoring in daily practice via the direct mode provides a more recognizable UA trace.

Medical legal issues in fetal monitoring

Despite almost universal fetal monitoring during labor, debates over its role and benefits persist in the medical community and in obstetric negligence lawsuits. Irrespective, there is widespread agreement that improvement in perinatal outcome is possible and that the events of labor contribute significantly to perinatal hazards. Timely application and proper interpretation of the fetal heart rate pattern in concert with evaluations of the maternal condition and the feasibility of safe vaginal delivery permit an evaluation of the quality of care and the preventability of fetal injury whether in peer review or in malpractice cases.

Prevention of birth asphyxia: responding appropriately to cardiotocograph (CTG) traces

Birth asphyxia is a broad term that refers to intrapartum asphyxia sufficient to cause neurological damage in some newborns and, rarely, intrapartum or neonatal death. Cerebral palsy and long-term neurological complications such as learning difficulties and motor impairments may be due to causes other than birth asphyxia. Several intrapartum events may cause asphyxia (i.e. hypoxia and metabolic acidosis) leading to the likelihood of neurological injury. The cardiotocograph (CTG) is a screening tool that is used to assess fetal well-being during labour and to identify the possibility of asphyxia. Abnormality of the CTG, sometimes severe enough to be described as a pathological trace, is commonly termed 'fetal distress', although many fetuses with such traces may not have hypoxia and metabolic acidosis. In current practice, the events are appropriately termed 'pathological CTG trace' or 'acidotic pH' rather than 'fetal distress'. Accurate interpretation of CTG is essential, and it is important to recognize a fetus that shows a pathological CTG in labour that may imply possible hypoxia and birth asphyxia. Considering the wider clinical picture in interpreting the CTG, and taking timely and appropriate action based on the findings, may help prevent birth asphyxia.

Norwegian midwives’ perception of the labour admission test

OBJECTIVE

To explore what information and knowledge the labour admission test is perceived to provide and what meaning the test carries in the daily work of practising midwives.

DESIGN

In-depth interviews transcribed verbatim and analysed using the grounded theory technique.

SETTING

Four different labour wards in Norway.

PARTICIPANTS

A theoretical sample of 12 practising midwives.

FINDINGS

The core category "experiencing contradictions" was identified during the analyses, indicating that the midwives found conflicting interests within themselves, or between themselves and others when using the labour admission test. They experienced contradictions between professional identity and the increasing use of technology, between feeling safe and feeling unsafe and between having power and being powerless.

KEY CONCLUSIONS

The labour admission traces could be difficult to interpret, especially for newly qualified midwives. Some midwives thought that a labour admission trace could protect them in case of litigation. The hierarchy of power in the labour ward influences the use and interpretation of the labour admission test. Some midwives felt their professional identity threatened and that midwives in general are losing their traditional skills because of the increasing use of obstetric technology.

IMPLICATIONS FOR PRACTICE

The findings of the present study should be taken into consideration when changing practice to not routinely perform the labour admission test. There is also a need for further research on what effect the increasing use of obstetric technology has on traditional midwifery skills.

Fetal source extraction from magnetocardiographic recordings by dependent component analysis

Fetal magnetocardiography (fMCG) has been extensively reported in the literature as a non-invasive, prenatal technique that can be used to monitor various functions of the fetal heart. However, fMCG signals often have low signal-to-noise ratio (SNR) and are contaminated by strong interference from the mother's magnetocardiogram signal. A promising, efficient tool for extracting signals, even under low SNR conditions, is blind source separation (BSS), or independent component analysis (ICA). Herein we propose an algorithm based on a variation of ICA, where the signal of interest is extracted using a time delay obtained from an autocorrelation analysis. We model the system using autoregression, and identify the signal component of interest from the poles of the autocorrelation function. We show that the method is effective in removing the maternal signal, and is computationally efficient. We also compare our results to more established ICA methods, such as FastICA.