Abstract
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
- 1.If maternal heart rate artefact is unrecognized and a concerning fetal heart rate is masked by a maternal heart rate tracing that mimics a normal/atypical fetal heart rate tracing, there is an increased risk of intrapartum fetal death, neonatal death, neonatal acidemia at birth, and hypoxic-ischemic encephalopathy (low).
- 2.If maternal heart rate artefact is unrecognized and a normal fetal heart rate is masked by a maternal heart rate tracing that mimics an atypical/abnormal fetal heart rate tracing, there is an increased risk of unnecessary intervention, including cesarean delivery or operative vaginal delivery (low).
- 3.In late-first and second stage of labour, fetal and maternal heart rates are frequently within the same range. As a result, the risk of maternal heart rate artefact is greatest and the artefact is most difficult to detect, often involving a subtle switch between the 2 signals, with no discernable change in baseline rate (moderate).
- 4.Maternal heart rate artefact is common during external fetal heart rate monitoring (moderate) and intermittent auscultation (low). It also occurs, but less frequently, with internal fetal monitoring (low).
RECOMMENDATIONS
- 1.Clinicians should be aware that modern fetal monitors may seamlessly transition from capturing the fetal heart rate to capturing the maternal heart rate with no apparent break in the tracing (strong, low).
- 2.Clinicians should consider the possibility of maternal heart rate artefact when monitoring the fetal heart rate. A high index of suspicion is indicated when the presumed fetal heart rate is similar to the maternal heart rate; abruptly improves from a previously atypical/abnormal pattern without an explanation; shows accelerations during contractions and/or maternal pushing; demonstrates wide variations, changes in baseline heart rate, or an abrupt change in variability; demonstrates halving or doubling in the baseline heart rate; and/or is difficult to interpret (strong, low).
- 3.We recommend that the obstetrical care team be aware of technology to detect maternal heart rate and understand how to use it (strong, low). When maternal heart rate detection technology is available, we suggest using it whenever performing fetal heart rate monitoring (conditional, low) and we recommend using it in the following circumstances: when the maternal heart rate is elevated to within the fetal range, when artefact is suspected on the basis of clinical features (see Recommendation 2), and during the active second stage of labour (strong, low).
- 4.Health care providers performing intermittent auscultation should assess the maternal pulse and initiate continuous electronic fetal monitoring if the maternal heart rate is similar to the fetal heart rate (strong, low).
- 5.When maternal heart rate artefact is suspected on the basis of clinical features during electronic fetal monitoring and/or on the basis of coincidence alarms, we recommend taking the following steps in an escalating fashion until artefact is ruled out: (1) optimize position of the fetal heart rate transducer and initiate continuous monitoring of the maternal heart rate with a pulse oximeter if not already started; (2) perform point-of-care sonography, if available, to confirm the fetal heart rate, and position the external fetal heart rate transducer under direct vision; and (3) apply a fetal scalp electrode if there are no contraindications (preferred) and/or augment continuous external fetal monitoring with continuous or repeated point-of-care sonographic assessments (if available) of the fetal heart rate (alternative, less preferred because of its limitations) (strong, low).
- 6.If there is ongoing suspicion of maternal heart rate artefact and uncertainty about whether the fetal heart rate tracing is accurate despite attempts at optimization, we recommend expediting delivery, depending on the overall clinical context (strong, low).
- 7.We advise vigilance concerning intrapartum maternal heart rate artefact at the initiation of fetal heart rate monitoring (conditional, low). Health care providers should be aware of reported cases of undiagnosed intrauterine fetal death, in which the maternal heart rate was interpreted as the fetal heart rate and an emergency cesarean delivery was performed. If this clinical scenario is suspected, we suggest point-of-care sonography to directly visualize the fetal heart rate before cesarean delivery, provided this technology is available and visualization can be performed within an acceptable timeframe, given the overall clinical context (conditional, low).
- 8.When maternal heart rate detection technologies are unavailable, we suggest that the maternal heart rate be continuously monitored with a pulse oximeter during intrapartum fetal heart rate monitoring (conditional, low) and recommend vigilance concerning the clinical features of maternal heart rate artefact (strong, low).
- 9.We recommend following the same principles in the previous recommendations during delivery for multiple gestation. However, these deliveries are more complex and require additional vigilance because maternal heart rate artefact may occur with one or more of the fetuses. As well, health care providers should be vigilant concerning the possibility of multiple gestation heart rate artefact, which occurs when 2 or more fetal heart rate signals are confused and/or 2 fetal heart rate transducers are inadvertently monitoring the same fetus (strong, low).
Keywords
Abbreviations:
FHR (fetal heart rate), MHR (maternal heart rate), MHRA (maternal heart rate artefact)To read this article in full you will need to make a payment
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References
- Signal ambiguity resulting in unexpected outcome with external fetal heart rate monitoring.Am J Obstet Gynecol. 2008; 198: 717-724
- The incidence of maternal artefact during intrapartum fetal heart rate monitoring.J Obstet Gynaecol Can. 2014; 36: 962-968
- Fetal heart rate monitoring.4th ed. Lippincott Williams & Wilkins, Philadelphia, PA2012
- Munro Kerr's operative obstetrics.Elsevier, 2014
- Handbook of CTG interpretation: from patterns to physiology.Cambridge University Press, Cambridge, UK2017
- Maternal or fetal heart rate? Avoiding intrapartum misidentification.J Obstet Gynecol Neonatal Nurs. 2004; 33: 93-104
- Unrecognized maternal heart rate artefact in cases of perinatal mortality reported to the United States Food and Drug Administration from 2009 to 2019: a critical patient safety issue.BMC Pregnancy Childbirth. 2019; 19: 501
- Medical legal issues in fetal monitoring.Clin Perinatol. 2007; 34 (, vii): 329-343
- Improvements in fetal heart rate analysis by the removal of maternal-fetal heart rate ambiguities.BMC Pregnancy Childbirth. 2015; 15: 301
- Intrapartum heart rate ambiguity: a comparison of cardiotocogram and abdominal fetal electrocardiogram with maternal electrocardiogram.Gynecol Obstet Invest. 2013; 75: 101-108
- Limitations of autocorrelation in fetal heart rate monitoring.Am J Obstet Gynecol. 1985; 153: 685-692
- Autocorrelation techniques in fetal monitoring.Am J Obstet Gynecol. 1985; 151: 2-6
- Advances in electronic fetal monitors--real or imaginary.J Perinat Med. 1986; 14: 405-410
- Cardiotocography and beyond: a review of one-dimensional Doppler ultrasound application in fetal monitoring.Physiol Meas. 2018; 39: 08tr1
- National clinical guideline for intrapartum FHR monitoring: Ireland 2019.(Available at:)
- Maternal heart rate in labour and the potential for confusion with fetal heart rate [20L].Obstet Gynecol. 2020; 135: 129S
- Incidence of maternal tachycardia during the second stage of labour: a prospective observational cohort study.J Matern Fetal Neonatal Med. 2019; 32: 1615-1619
- Five years of cerebral palsy claims: a thematic review of NHS resolution data.(Available at:)https://resolution.nhs.uk/wp-content/uploads/2017/09/Five-years-of-cerebral-palsy-claims_A-thematic-review-of-NHS-Resolution-data.pdfDate: September 2017Date accessed: February 3, 2022
Ontario Maternal and Perinatal Death Review Committee: 2019 annual report [Case N-11]. Available at: https://www.ontario.ca/document/maternal-and-perinatal-death-review-committee-2019-annual-report/appendix-summary-cases-examined-2019. Accessed on February 3, 2022.
- Class 2 device recall Philips Avalon fetal monitor 2009.(Available at:)https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfres/res.cfm?id=86827Date accessed: February 2, 2022
- Recalls and safety alerts. Avalon fetal monitors.(Available at:)http://www.healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2009/26845r-eng.phpDate: 2009Date accessed: February 2, 2022
- New safety reviews. Safety reviews started between 2018-06-01 and 2018-06-30. Avalon fetal monitor (FM20, FM30, FM40, FM50) (medical device) 2018.(Available at:)https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-canada/safety-reviews/new.htmlDate accessed: February 2, 2022
- The National Archives. Philips Healthcare. Urgent – medical device recall. Philips Avalon fetal monitors FM20, FM30, FM40, FM50 (30 November 2009).(Available at:)
- The National Archives. Philips Healthcare – addendum. Additional information regarding ultrasound fetal monitoring (Nov 2009).(Available at:)
- The National Archives. Philips Healthcare. Important device safety alert (20 September 2009).(Available at:)
- Fetal monitor/cardiotocograph (CTG) - adverse outcomes still reported 2014.(Available at:)https://www.gov.uk/drug-device-alerts/medical-device-alert-fetal-monitor-cardiotocograph-ctg-adverse-outcomes-still-reportedDate accessed: February 2, 2022
- When signals become crossed: maternal-fetal signal ambiguity.J Perinat Neonatal Nurs. 2019; 33: 105-107
- Accuracy and reliability of fetal heart rate monitoring using maternal abdominal surface electrodes.Acta Obstet Gynecol Scand. 2012; 91: 1306-1313
- Misidentification of maternal heart rate as fetal on cardiotocography during the second stage of labour: the role of the fetal electrocardiograph.Acta Obstet Gynecol Scand. 2012; 91: 1428-1432
- False interpretation of fetal heart role monitoring in cases of intra-uterine death.S Afr Med J. 1976; 50 (1963–5)
- Documentation of recent fetal demise with simultaneous maternal and fetal heart rate monitoring.Obstet Gynecol. 1980; 55: 28s-30s
- Maternal ECG recorded by internal monitoring closely mimicking fetal heart rate in a recent fetal death.Int J Gynaecol Obstet. 1990; 33: 269-271
- Misinterpretation of fetal heart rate monitoring in case of intrauterine death.Clin Exp Obstet Gynecol. 1984; 11: 126-129
- Artifactual fetal electrocardiographic detection using internal monitoring following intrapartum fetal demise during VBAC trial.J Matern Fetal Med. 2000; 9: 360-361
- Characteristics of maternal heart rate patterns during labour and delivery.Obstet Gynecol. 2002; 99: 542-547
- Characteristics of fetal and maternal heart rate tracings during labour: a prospective observational study.J Neonatal Perinatal Med. 2019; 12: 405-410
- Maternal heart rate patterns in the first and second stages of labour.Acta Obstet Gynecol Scand. 2012; 91: 598-604
- Common documentation library, clinical systems. User manuals for: Corometrics 170 series, Corometrics 250 series, Corometrics 250CX Series.(Available at:)http://apps.gehealthcare.com/servlet/ClientServlet?REQ=Enter%2bDocumentation%2bLibraryDate accessed: February 2, 2022
- Instructions for use. Avalon fetal monitor. FM20/30, FM 40/50, Avalon CL. Release J.3 with software revision J.3x.xx.(Available at:)http://incenter.medical.philips.com/Default.aspx?tabid=4793(InCenter Access Form required)Date accessed: February 3, 2022
- FM20/30/40/50 & CL Avalon fetal monitor rel. J.3 training guide 4535 644 94131 (ENG).(Available at:)http://incenter.medical.philips.com/Default.aspx?tabid=4793(In Center Access Form required)Date accessed: February 3, 2022
- FIGO consensus guidelines on intrapartum fetal monitoring: cardiotocography.Int J Gynaecol Obstet. 2015; 131: 13-24
- Technical characteristics of current cardiotocographic monitors.Best Pract Res Clin Obstet Gynaecol. 2016; 30: 22-32
- No. 396-fetal health surveillance: intrapartum consensus guideline.J Obstet Gynaecol Can. 2020; 42: 316-348.e9
- Computer analysis of maternal-fetal heart rate recordings during labour in relation with maternal-fetal attachment and prediction of newborn acidemia.J Matern Fetal Neonatal Med. 2016; 29: 1440-1444
- Risk management in intrapartum fetal monitoring: accidental recording of the maternal heart rate.J Perinat Neonatal Nurs. 2010; 24: 7-9
- Figshare. 3 cases involving third party central fetal surveillance systems (from the review of all cases of adverse events related to fetal heart rate monitoring devices reported to Health Canada, Oct 2011 to August 6, 2018).(Available at:)
- Misidentification of maternal for fetal heart rate patterns after delivery of the first twin.J Perinat Med. 2009; 37: 177-179
Article info
Publication history
No. 429, September 2022
Footnotes
This document reflects emerging clinical and scientific advances as of the publication date and is subject to change. The information is not meant to dictate an exclusive course of treatment or procedure. Institutions are free to amend the recommendations. The SOGC suggests, however, that they adequately document any such amendments.
Informed consent: Patients have the right and responsibility to make informed decisions about their care in partnership with their health care provider. In order to facilitate informed choice, patients should be provided with information and support that is evidence-based, culturally appropriate, and personalized. The values, beliefs and individual needs of each patient in the context of their personal circumstances should be considered and the final decision about care and treatment options chosen by the patient should be respected.
Language and inclusivity: The SOGC recognizes the importance to be fully inclusive and when context is appropriate, gender-neutral language will be used. In other circumstances, we continue to use gendered language because of our mission to advance women’s health. The SOGC recognizes and respects the rights of all people for whom the information in this document may apply, including but not limited to transgender, non-binary, and intersex people. The SOGC encourages health care providers to engage in respectful conversation with their patients about their gender identity and preferred gender pronouns and to apply these guidelines in a way that is sensitive to each person’s needs.
Identification
Copyright
© 2022 The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada. Published by Elsevier Inc. All rights reserved.
