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

      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)
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      References

        • Neilson Jr., D.R.
        • Freeman R.K.
        • Mangan S.
        Signal ambiguity resulting in unexpected outcome with external fetal heart rate monitoring.
        Am J Obstet Gynecol. 2008; 198: 717-724
        • Paquette S.
        • Moretti F.
        • O'Reilly K.
        • et al.
        The incidence of maternal artefact during intrapartum fetal heart rate monitoring.
        J Obstet Gynaecol Can. 2014; 36: 962-968
        • Freeman R.K.
        • Garite T.J.
        • Nageotte M.P.
        • et al.
        Fetal heart rate monitoring.
        4th ed. Lippincott Williams & Wilkins, Philadelphia, PA2012
        • Baskett T.F.
        • Calder A.A.
        • Arulkumaran S.
        Munro Kerr's operative obstetrics.
        Elsevier, 2014
        • Chandraharan E.
        Handbook of CTG interpretation: from patterns to physiology.
        Cambridge University Press, Cambridge, UK2017
        • Murray M.L.
        Maternal or fetal heart rate? Avoiding intrapartum misidentification.
        J Obstet Gynecol Neonatal Nurs. 2004; 33: 93-104
        • Kiely D.J.
        • Oppenheimer L.W.
        • Dornan J.C.
        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
        • Schifrin B.S.
        • Cohen W.R.
        Medical legal issues in fetal monitoring.
        Clin Perinatol. 2007; 34 (, vii): 329-343
        • Pinto P.
        • Costa-Santos C.
        • Gonçalves H.
        • et al.
        Improvements in fetal heart rate analysis by the removal of maternal-fetal heart rate ambiguities.
        BMC Pregnancy Childbirth. 2015; 15: 301
        • Reinhard J.
        • Hayes-Gill B.R.
        • Schiermeier S.
        • et al.
        Intrapartum heart rate ambiguity: a comparison of cardiotocogram and abdominal fetal electrocardiogram with maternal electrocardiogram.
        Gynecol Obstet Invest. 2013; 75: 101-108
        • Fukushima T.
        • Flores C.A.
        • Hon E.H.
        • et al.
        Limitations of autocorrelation in fetal heart rate monitoring.
        Am J Obstet Gynecol. 1985; 153: 685-692
        • Divon M.Y.
        • Torres F.P.
        • Yeh S.Y.
        • et al.
        Autocorrelation techniques in fetal monitoring.
        Am J Obstet Gynecol. 1985; 151: 2-6
        • Carter M.C.
        Advances in electronic fetal monitors--real or imaginary.
        J Perinat Med. 1986; 14: 405-410
        • Marzbanrad F.
        • Stroux L.
        • Clifford G.D.
        Cardiotocography and beyond: a review of one-dimensional Doppler ultrasound application in fetal monitoring.
        Physiol Meas. 2018; 39: 08tr1
        • McKenna P.
        • Dunne A.
        • McGrane K.
        • et al.
        National clinical guideline for intrapartum FHR monitoring: Ireland 2019.
        (Available at:)
        • Oppenheimer L.W.
        • Faught E.
        Maternal heart rate in labour and the potential for confusion with fetal heart rate [20L].
        Obstet Gynecol. 2020; 135: 129S
        • Towers C.V.
        • Trussell J.
        • Heidel R.E.
        • et al.
        Incidence of maternal tachycardia during the second stage of labour: a prospective observational cohort study.
        J Matern Fetal Neonatal Med. 2019; 32: 1615-1619
        • Magro M.
        Five years of cerebral palsy claims: a thematic review of NHS resolution data.
        (Available at:)
      1. 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.

        • US Food and Drug Administration
        Class 2 device recall Philips Avalon fetal monitor 2009.
        (Available at:)
        • Government of Canada
        Recalls and safety alerts. Avalon fetal monitors.
        (Available at:)
        • Government of Canada HC
        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:)
      2. The National Archives. Philips Healthcare. Urgent – medical device recall. Philips Avalon fetal monitors FM20, FM30, FM40, FM50 (30 November 2009).
        (Available at:)
      3. The National Archives. Philips Healthcare – addendum. Additional information regarding ultrasound fetal monitoring (Nov 2009).
        (Available at:)
      4. The National Archives. Philips Healthcare. Important device safety alert (20 September 2009).
        (Available at:)
        • Medicines and Healthcare Products Regulatory Agency
        Fetal monitor/cardiotocograph (CTG) - adverse outcomes still reported 2014.
        (Available at:)
        • Cypher R.L.
        When signals become crossed: maternal-fetal signal ambiguity.
        J Perinat Neonatal Nurs. 2019; 33: 105-107
        • Cohen W.R.
        • Ommani S.
        • Hassan S.
        • et al.
        Accuracy and reliability of fetal heart rate monitoring using maternal abdominal surface electrodes.
        Acta Obstet Gynecol Scand. 2012; 91: 1306-1313
        • Nurani R.
        • Chandraharan E.
        • Lowe V.
        • et al.
        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
        • Odendaal H.J.
        False interpretation of fetal heart role monitoring in cases of intra-uterine death.
        S Afr Med J. 1976; 50 (1963–5)
        • Barrett J.M.
        • Boehm F.H.
        Documentation of recent fetal demise with simultaneous maternal and fetal heart rate monitoring.
        Obstet Gynecol. 1980; 55: 28s-30s
        • Herman A.
        • Ron-El R.
        • Arieli S.
        • et al.
        Maternal ECG recorded by internal monitoring closely mimicking fetal heart rate in a recent fetal death.
        Int J Gynaecol Obstet. 1990; 33: 269-271
        • Achiron R.
        • Zakut H.
        Misinterpretation of fetal heart rate monitoring in case of intrauterine death.
        Clin Exp Obstet Gynecol. 1984; 11: 126-129
        • Ramsey P.S.
        • Johnston B.W.
        • Welter V.E.
        • et al.
        Artifactual fetal electrocardiographic detection using internal monitoring following intrapartum fetal demise during VBAC trial.
        J Matern Fetal Med. 2000; 9: 360-361
        • Sherman D.J.
        • Frenkel E.
        • Kurzweil Y.
        • et al.
        Characteristics of maternal heart rate patterns during labour and delivery.
        Obstet Gynecol. 2002; 99: 542-547
        • Ramadan M.K.
        • Fasih R.
        • Itani S.
        • et al.
        Characteristics of fetal and maternal heart rate tracings during labour: a prospective observational study.
        J Neonatal Perinatal Med. 2019; 12: 405-410
        • Van Veen T.R.
        • Belfort M.A.
        • Kofford S.
        Maternal heart rate patterns in the first and second stages of labour.
        Acta Obstet Gynecol Scand. 2012; 91: 598-604
        • General Electric Healthcare
        Common documentation library, clinical systems. User manuals for: Corometrics 170 series, Corometrics 250 series, Corometrics 250CX Series.
        (Available at:)
        • Philips Healthcare
        Instructions for use. Avalon fetal monitor. FM20/30, FM 40/50, Avalon CL. Release J.3 with software revision J.3x.xx.
        (Available at:) (InCenter Access Form required)
        • Philips Healthcare
        FM20/30/40/50 & CL Avalon fetal monitor rel. J.3 training guide 4535 644 94131 (ENG).
        (Available at:) (In Center Access Form required)
        • Ayres-de-Campos D.
        • Spong C.Y.
        • Chandraharan E.
        FIGO consensus guidelines on intrapartum fetal monitoring: cardiotocography.
        Int J Gynaecol Obstet. 2015; 131: 13-24
        • Ayres-de-Campos D.
        • Nogueira-Reis Z.
        Technical characteristics of current cardiotocographic monitors.
        Best Pract Res Clin Obstet Gynaecol. 2016; 30: 22-32
        • Dore S.
        • Ehman W.
        No. 396-fetal health surveillance: intrapartum consensus guideline.
        J Obstet Gynaecol Can. 2020; 42: 316-348.e9
        • Pinto P.
        • Costa-Santos C.
        • Ayres-de-Campos D.
        • et al.
        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
        • Hanson L.
        Risk management in intrapartum fetal monitoring: accidental recording of the maternal heart rate.
        J Perinat Neonatal Nurs. 2010; 24: 7-9
        • Kiely D.J.
        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:)
        • Muñoz Brands R.M.
        • Bakker P.C.
        • Bolte A.C.
        • et al.
        Misidentification of maternal for fetal heart rate patterns after delivery of the first twin.
        J Perinat Med. 2009; 37: 177-179