Misidentification of maternal for fetal heart rate patterns after delivery of the first twin

Technical Update No. 429: Maternal Heart Rate Artefact During Intrapartum Fetal Health Surveillance

OBJECTIVE

To improve perinatal outcomes and minimize provider error by increasing awareness of strategies to detect intrapartum maternal heart rate artefact and to respond when such artefact is suspected.

TARGET POPULATION

All pregnant patients during labour.

OPTIONS

Maternal heart rate artefact may be detected based on clinical features or through technology. Suspected maternal heart rate artefact may be assessed by applying a fetal scalp electrode (preferred) or through external fetal monitoring, augmented by point-of-care sonography (alternative).

OUTCOMES

Unrecognized intrapartum maternal heart rate artefact increases the risk that abnormal/atypical fetal heart rate patterns will go undetected and, hence, the risk of adverse perinatal outcomes.

BENEFITS, HARMS, AND COSTS

Unrecognized maternal heart rate artefact can lead to adverse perinatal outcomes (hypoxic-ischemic encephalopathy, fetal death, and neonatal death) and adverse maternal outcomes (unnecessary cesarean delivery or operative vaginal delivery). Timely recognition of such artefact may avoid these adverse outcomes. The costs of early recognition of maternal heart rate artefact are relatively small: increased use of fetal scalp electrodes and point-of-care sonography, as well as additional assessments by the health care provider. The cost savings are significant, as a result of lower risk of adverse perinatal outcomes. Potential harms are false-positive diagnoses of maternal heart rate artefact, expediting delivery unnecessarily when the fetal status cannot be reliably determined but is normal, and the rare complications associated with increased use of fetal scalp electrodes.

EVIDENCE

Two PubMed searches were completed. The first was for articles published between January 1, 1970, and November 25, 2021, using the medical subject headings (MeSH) "fetal monitoring" and "artifacts" (38 articles). The second was for articles published during the same period using the MeSH "fetal monitoring" and "maternal heart rate" (841 articles).

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

All health care providers involved in obstetrical care.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Mise à jour technique no 429 : Artéfact de la fréquence cardiaque maternelle pendant la surveillance du bien-être fœtal per partum

OBJECTIF

Améliorer les issues périnatales et réduire au minimum le risque d'erreurs chez les fournisseurs en améliorant leurs connaissances sur les stratégies de détection des artéfacts de la fréquence cardiaque maternelle per partum et sur les modes d'intervention lorsque de tels artéfacts sont soupçonnés.

POPULATION CIBLE

Toutes les parturientes.

OPTIONS

L'artéfact de la fréquence cardiaque maternelle peut être détecté à l'aide de caractéristiques cliniques ou de la technologie. On peut évaluer l'artéfact de la fréquence cardiaque maternelle soupçonné en posant une électrode de cuir chevelu fœtal (option à privilégier) ou en recourant à la surveillance fœtale externe optimisée par l'échographie au chevet (solution de rechange). RéSULTATS: Les artéfacts de la fréquence cardiaque maternelle per partum non détectés augmentent le risque que des rythmes anormaux ou atypiques de la fréquence cardiaque fœtale passent inaperçus, ce qui augmente le risque d'issues périnatales défavorables. BéNéFICES, RISQUES ET COûTS: L'artéfact de la fréquence cardiaque maternelle non détecté peut entraîner de graves issues périnatales défavorables (encéphalopathie hypoxo-ischémique, mort fœtale et mort néonatale) et des issues maternelles défavorables (césarienne injustifiée ou accouchement assisté). Ces issues peuvent être évitées par la détection rapide d'un tel artéfact. Le coût de la détection précoce des artéfacts de fréquence cardiaque maternelle est relativement faible (utilisation accrue des électrodes de cuir chevelu fœtal et de l'échographie au chevet avec évaluations supplémentaires par le fournisseur de soins). La réduction des événements périnataux défavorables engendre des économies considérables. Les risques sont : faux positifs d'artéfact de la fréquence cardiaque maternelle; accélération inutile de l'accouchement lorsque l'état du fœtus est normal, mais qu'on ne peut le déterminer de façon fiable; et les rares complications associées à l'utilisation accrue des électrodes de cuir chevelu fœtal. DONNéES PROBANTES: Deux recherches ont été effectuées dans PubMed. La première a été réalisée pour répertorier les articles publiés entre le 1^er janvier 1970 et le 25 novembre 2021 à partir des termes MeSH fetal monitoring et artifacts (38 articles); la deuxième, pour répertorier les articles publiés au cours de la même période à partir des termes MeSH fetal monitoring et maternal heart rate (841 articles). MéTHODES DE VALIDATION: Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Tous les fournisseurs de soins obstétricaux. DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Characteristics of fetal and maternal heart rate tracings during labor: A prospective observational study

BACKGROUND

Fetal well-being is assured during labor and delivery with the employment of electronic fetal heart monitoring (EFHM). In uncommon instances, maternal heart rate (MHR) instead of fetal heart rate (FHR) can be the source of signals on monitors (signal ambiguity) leading to erroneous interpretation and management. Information about MHR characteristics are comparatively inadequate. We aim to analyze and compare MHR and FHR characteristics during the first and second stages of labor.

METHODS

A prospective cohort study was conducted in a single tertiary care center during a one year period. Fifty one healthy full term women with singleton pregnancies during labor were enrolled. Uterine contractions, MHR and FHR were recorded simultaneously during both stages of labor by monitors designed for twin gestation.

RESULTS

When compared to FHR, MHR had significantly lower baseline rate during 1st and 2nd stages (p < 0.0001). It demonstrated also more marked beat-to-beat variability during both stages (p < 0.0001). MHR showed significantly more accelerations (p = 0.03 and p = 0.008) and less decelerations (p < 0.0001 and p = 0.021) during 1st and 2nd stages respectively.

CONCLUSIONS

All characteristic parameters and patterns produced by FHR could be mimicked by MHR as well, though, at different frequencies. Understanding EFHM patterns suspected to be MHR artefacts and the employment of modern monitors that simultaneously obtain and display FHR and MHR can unmask ambiguity and avert related misinterpretation problems. Similar studies should be conducted in high-risk groups where the potential for fetal hypoxia/acidosis is increased.

The effect of perceptual decision-making on the interpretation of twin fetal heart rate tracings

Objective: Decision-making is an integrative process during which multiple sources of available evidence are combined into a singular response. Importantly, subconscious processes occur in perceptual decisions that may influence interpretations of visually displayed data such as fetal heart rate tracings (FHRT), which are typically presented together for twins. To examine the potential impact of subconscious perceptual influences on fetal well-being, differences in assessments of FHRTs for twin gestations presented singly or paired were evaluated for baseline fetal heart rate, variability, accelerations, decelerations, and overall concern.Study design: Obstetrical nurses (N = 27) assessed FHRTs from 20 twin gestations (each of which had at least one live birth with a 5-min Apgar <7) presented either on the same tracing or as singletons on separate tracings. Nurses were naïve to the fact that the fetal heart rate tracings presented in the unpaired condition were the same as those presented in the paired condition. Assessments were then compared between the two conditions.Results: Each nurse participant completed ratings on five metrics for each of 20 twin gestations across two conditions (80 FHRT assessments, 400 metrics total per participant). The intraobserver impact of visual context was calculated as the frequency of changed opinions regarding an individual metric (e.g. variability) between the paired and unpaired contexts for each individual fetal heart rate. Assessments of variability (average Kappa = 0.59), decelerations (average Kappa = 0.34), and overall level of concern (average Kappa = 0.33) were moderately to heavily impacted by viewing condition (unpaired vs. paired FHRT). Analysis of interobserver agreement using intraclass correlations (two-way random effect, absolute agreement) indicates poor agreement on unpaired assessments for both accelerations (ICC = 0.01, 95% CI -0.01-0.04) and decelerations (ICC = 0.22, 95% CI 0.15-0.33). These results are mirrored in poor agreement on paired assessments for both accelerations (ICC = 0.00, 95% CI -0.01-0.03) and decelerations (ICC = 0.27, 95% CI 0.19-0.39). There was moderate agreement on overall level of concern for unpaired assessments (ICC = 0.55, 95% CI 0.44-0.67) and near moderate agreement for the paired condition (ICC = 0.45, 95% CI 0.34-0.58).Conclusions: The simultaneous presentation of fetal heart rate tracings in twin gestations introduces both intraobserver and interobserver variances in the interpretation of variability, accelerations, and decelerations, likely due to the influence of subconscious perceptual decision-making. This may theoretically affect outcomes in cases in which visual information is nuanced. More research is necessary to determine whether the standard protocol of simultaneous assessment of FHRT in twins is subliminally affected by perceptual decision-making.

Maternal heart rate patterns under resting conditions in late pregnancy

Objectives:

To describe maternal heart rate patterns observed during antenatal monitoring under resting conditions between the gestational ages of 34 to 38 weeks and to demonstrate its associations with uterine activity.

Methods:

Each participant had five high quality ECG electrodes attached to her anterior abdominal wall which were connected to the Monica AN24 device to collect raw electrical signals from the maternal and fetal ECG and signals of uterine activity. Proprietary software was then used to download the raw data and extract the maternal and fetal heart rate patterns and uterine activity.

Results:

Several distinct maternal heart rate patterns were observed. These included unusually high or low levels of variability, tachycardia, bradycardia, regular and irregular periodic changes and sporadic changes where the heart rate suddenly decreased or increased. Some of the fluctuations, especially decelerations of maternal heart rate, seemed to be associated with uterine activity.

Conclusion:

The clinical implications of these different patterns, for both the mother and fetus, needs to be explored further. There is a need for computerized analyses of the different maternal patterns during different gestational ages to determine its relevance.

Synopsis

Various maternal heart rate patterns under resting conditions in late pregnancy are described.

Improvements in fetal heart rate analysis by the removal of maternal-fetal heart rate ambiguities

Background

Misinterpretation of the maternal heart rate (MHR) as fetal may lead to significant errors in fetal heart rate (FHR) interpretation. In this study we hypothesized that the removal of these MHR-FHR ambiguities would improve FHR analysis during the final hour of labor.

Methods

Sixty-one MHR and FHR recordings were simultaneously acquired in the final hour of labor. Removal of MHR-FHR ambiguities was performed by subtracting MHR signals from their FHR counterparts when the absolute difference between the two was less or equal to 5 beats per minute. Major MHR-FHR ambiguities were defined when they exceeded 1 % of the tracing. Maternal, fetal and neonatal characteristics were evaluated in cases where major MHR-FHR ambiguities occurred and computer analysis of FHR recordings was compared, before and after removal of the ambiguities.

Results

Seventy-two percent of tracings (44/61) exhibited episodes of major MHR-FHR ambiguities, which were not significantly associated with any maternal, fetal or neonatal characteristics, but were associated with MHR accelerations, FHR signal loss and decelerations. Removal of MHR-FHR ambiguities resulted in a significant decrease in FHR decelerations, and improvement in FHR tracing classification.

Conclusions

FHR interpretation during the final hour of labor can be significantly improved by the removal of MHR-FHR ambiguities.

Effect of maternal position and uterine activity on periodic maternal heart rate changes before elective cesarean section at term

INTRODUCTION

Because little is known about the effects of maternal position on periodic changes in the maternal heart rate (MHR) in late pregnancy, a prospective observational study was done at Tygerberg Academic Hospital in Cape Town. Pregnant women admitted for elective cesarean section were studied to determine the effect of changes in position on the maternal and fetal heart rates (FHR) and maternal blood pressure.

MATERIAL AND METHODS

Continuous transabdominal non-invasive recording of MHR, FHR patterns and uterine activity was done for 1 h in 119 women, using the AN24 device from Monica Health Care. Maternal position was changed every 15 min from lateral to supine, then to the other lateral position and finally supine again. Blood pressure was measured in the left arm and left lower leg three times during each 15-min period.

RESULTS

MHRs were four beats per minute slower in the left lateral position than in the right lateral position. Periodic MHR changes were seen in 13 (10.9%) women. Most of these (84.6%) were associated with uterine activity and not with maternal position. No changes in FHR patterns were observed after position changes.

CONCLUSIONS

In a subgroup of pregnant women at term, uterine activity was associated with periodic decelerations of the MHR. In low risk pregnancies there seems to be no effect on the FHR pattern. Implications for the compromised fetus have not yet been investigated.

[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.