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Continuous Electronic Fetal Monitoring (Cardiotocography) in Labor: Should It Be Routine?

September 3rd, 2013 by avatar

Regular Science & Sensibility contributor and author Henci Goer takes a look at the recent Cochrane review “Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour” to determine if the researchers found any new information on the benefits or risks of CTG for normal, low risk labors.  Read on to see if things might have changed and are the hospitals in your area conforming with recommendations of ACOG, SCOG and RCOG?  Are these recommendations based on the evidence?  - Sharon Muza, Community Manager, Science & Sensibility

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http://flic.kr/p/o43Lw

Almost all women laboring in U.S. hospitals undergo continuous electronic fetal monitoring (EFM) (Declercq 2006), but should they? A new iteration of the Cochrane systematic review of randomized controlled trials of EFM versus intermittent auscultation (listening) can answer that question (Alfirevic 2013).

The rationale behind continuous EFM was that insufficient oxygen (hypoxia) in labor was a major cause of intrapartum fetal death and permanent brain injury. It was thought that enhanced ability to pick up changes in fetal heart rate (FHR) patterns signaling distress would enable doctors to rescue the fetus in time to prevent perinatal death and cerebral palsy. Does that theory hold up in practice?

According to the Cochrane review, not so much—nor, I might add, is this news since all prior versions have reported the same results. Continuous EFM fails to decrease perinatal mortality, whether in women overall (11 trials, 33,513 participants) or in the subgroups of high-risk women (5 trials, 1974 participants), mixed-risk/risk not specified populations (3 trials, 15,490 participants), or low-risk women (3 trials, 16,049 participants). Neither does it reduce incidence of cerebral palsy whether in women overall (2 trials, 13,252 women) or in high-risk women (1 trial, 173 participants) or in a mixed-risk/risk not specified population (1 trial, 13,079). (No trial reported comparative cerebral palsy rates in low-risk women.) In fact, cerebral palsy rates were increased more than two-fold (risk ratio: 2.54) in the EFM group in the sole high-risk trial reporting this outcome, although with only 173 women and one trial, it is unclear what, if anything, should be made of this. The authors, noting that the delay between diagnosis and taking action was longer in the EFM group, speculated that EFM may have been providing a false sense of feeling in control of the situation (Shy 1990). So it turns out more information isn’t necessarily better information.

Continuous EFM isn’t a total washout. It reduces the incidence of neonatal seizure, which is of some benefit since neonatal seizure can indicate permanent brain injury, the likelihood of which depends on the severity of seizure and whether it is accompanied by other symptoms. Among women overall (9 trials, 32,386 participants), it halved seizure rates (risk ratio: 0.50). In high-risk populations (5 trials, 4805 participants), it reduced seizure rates (risk ratio: 0.67), but the difference failed to achieve statistical significance while in low-risk populations (3 trials, 25,175 participants), the reduction was by nearly two-thirds (risk ratio: 0.36), and in mixed-risk/risk not specified populations (2 trials, 2406 participants), the reduction approached 80% (risk ratio: 0.18). The reviewers calculate that with a baseline seizure risk of 3.0 per 1000 labors among women overall in the intermittent auscultation group, 667 women  would have to have continuous EFM in order to prevent 1 neonatal seizure. In low-risk women, in whom the baseline risk was 1.2 per 1000 labors with intermittent auscultation, my calculation raised that to 833 women.

Although continuous EFM fails in achieving its original goal of preventing perinatal death and cerebral palsy, the reduction in incidence of neonatal seizure would seem to argue for universal continuous EFM, were it not that this benefit comes at a price: continuous EFM increases the likelihood of cesarean surgery, and to a lesser degree, instrumental vaginal delivery, which increased among women overall by 15% (risk ratio: 1.15). Among women overall (11 trials, 18,861 participants), continuous EFM increased likelihood of cesarean by nearly two-thirds (risk ratio: 1.63); among high-risk women (6 trials, 2069 women), it doubled the risk (risk ratio: 1.91); it did the same (risk ratio: 2.06) among low-risk women (2 trials, 1431 participants) while among mixed-risk/risk not specified populations (3 trials, 15,361 participants), the rate was increased (risk ratio: 1.14), but the difference wasn’t statistically significant. The reviewers calculate that assuming a 15% cesarean rate with intermittent auscultation, one additional cesarean would be performed for every 11 women monitored, and 61 additional cesareans would be performed to prevent 1 seizure. In low-risk women, my calculation found that 1 additional cesarean would be performed for every 6 women monitored, and 76 additional cesareans would be performed to prevent 1 seizure.

The Cochrane reviewers conclude that women should be informed that EFM neither reduces perinatal mortality nor cerebral palsy and that while it reduces incidence of neonatal seizures, it does so at the cost of increased cesarean and instrumental vaginal deliveries. Cesarean and instrumental deliveries, I hardly need point out, have their own associated harms, some of them quite serious, and these must be set against the reduction in seizures (Childbirth Connection 2012; Goer 2012). The reviewers write:

Given the perceived conflict between the risk for the mother . . . and benefit for the baby . . . , it is difficult to make quality judgments as to which effect is more important. . . . The real challenge is how best to convey this uncertainty to women and help them to make an informed choice without compromising the normality of labour.

That gives us our marching orders, but how best might we carry them out? One reasonable course would be to see what obstetric guidelines advise.

http://flic.kr/p/98pfNc

The least decisive recommendation comes from the American Congress of Obstetricians and Gynecologists (2009), whose guidelines state: “Given that the available data do not show a clear benefit for the use of EFM over intermittent auscultation, either option is acceptable in a patient without complications” (p. 196). This suggests equivalency between the two, but, of course, they aren’t equivalent because continuous EFM increases likelihood of cesarean and instrumental vaginal delivery. ACOG further recommends that “the labor of women with high-risk conditions (eg, suspected fetal growth restriction, preeclampsia, and type 1 diabetes) should be monitored with continuous FHR monitoring” (p. 196), although they later acknowledge that this recommendation is based on “Level C” evidence, “expert opinion.”

The U.K. Royal College of Obstetricians and Gynaecologists takes a stronger stance: “Intermittent auscultation of the FHR is recommended for low-risk women in established labour in any birth setting” (p.155) (National Collaborating Center for Women’s and Children’s Health 2007). The Royal College advises switching to continuous EFM in low-risk women for these reasons:

  • significant meconium, with consideration for making the switch with light meconium
  • abnormal FHR is detected by intermittent auscultation
  • maternal fever
  • fresh bleeding developing in labor
  • oxytocin use for augmentation [I would assume this would also cover oxytocin induction.]
  • the woman’s request

The Canadian Society of Obstetricians and Gynaecologists provides the most detailed advice of all (Liston 2007). SOGC guidelines state: “Intermittent auscultation . . . is the recommended method of fetal surveillance [in healthy term women in spontaneous term labor who are free of risk factors for adverse perinatal outcome]” (p. S6). In women with risk factors for adverse perinatal outcome, the SOGC, like ACOG, recommends continuous EFM while acknowledging that “little scientific evidence” (p. S33) supports it. However, SOGC guidelines additionally state: “When a normal tracing is identified, it may be appropriate to interrupt the electronic fetal monitoring tracing for up to 30 minutes to facilitate periods of ambulation, bathing, or position change, providing that (1) the maternal-fetal condition is stable and (2) if oxytocin is being administered, the infusion rate is not increased” (p. S6).

The consistent recommendation that intermittent auscultation is preferable (in the case of RCOG and SOGC), or at least acceptable (in the case of ACOG), in low-risk women in spontaneous labor answers the question posed in the title. No, continuous EFM should not be routine, and we are on solid ground sharing this information and its sources with pregnant women.

Unfortunately, this doesn’t help most low-risk women laboring in U.S. hospitals because they will have either an epidural, be receiving oxytocin, or both. The SOGC guidelines can serve us here. With epidural analgesia, the guidelines state: “Intermittent auscultation may be used to monitor the fetus when epidural analgesia is used during labour, provided that a protocol is in place for frequent intermittent auscultation assessment (e.g., every 5 minutes for 30 minutes after epidural initiation and after bolus top-ups as long as maternal vital signs are normal)” (p. S6), and the SOGC guidelines treat induction and augmentation the same as women with risk factors, that is, with continuous EFM but permitting breaks if mother, baby, and oxytocin dose are stable. Suggesting that women in these categories request that their caregivers follow SOGC guidelines seems a pragmatic approach to achieving any benefits continuous EFM may provide while potentially reducing harms.

I could end here, but I can’t help asking: Why stop with search and rescue of hypoxic babies? Why not look at prevention? Among the 10,053 low-risk women at the Dublin Maternity Hospital, the neonatal seizure rates were 10 times (14 per 10,000 continuous EFM vs. 38 per 10,000 intermittent auscultation) those in the 14,618 women in the Dallas trial (1 per 10,000 continuous EFM vs. 4 per 10,000 intermittent auscultation) (Alfirevic 2013). I doubt that it’s coincidental that the Dublin Maternity Hospital is the home of Active Management of Labor, which prescribes routine early rupture of membranes and high doses of oxytocin with a short interval between dose increases for any woman not progressing at a minimum 1 cm dilation per hour. Early rupture of membranes, induction, and high-dose/short interval oxytocin regimens all increase stress on the fetus (Goer 2012). I think educators and doulas have a role to play here too. We can point women to Lamaze’s Healthy Birth Practices #1 and #4 to help them start a conversation with their care providers about labor induction and artificial rupture of membranes. And while women aren’t in a position to dictate oxytocin regimen, nurses and other hospital insiders can lobby for uniformly instituting the more physiologic oxytocin protocol found in Pitocin packaging if their hospital doesn’t mandate it already. An ounce of prevention is worth a pound of cure not the least because prevention has no adverse effects.

References

ACOG. (2009). Intrapartum fetal heart rate monitoring: nomenclature, interpretation, and general management principles. ACOG Practice Bulletin No. 106. http://www.ncbi.nlm.nih.gov/pubmed/19546798

Alfirevic, Z., Devane, D., & Gyte, G. M. (2013). Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database Syst Rev, 5, CD006066. doi: 10.1002/14651858.CD006066.pub2 http://www.ncbi.nlm.nih.gov/pubmed/23728657

Childbirth Connection. (2012). Vaginal or Cesarean Birth: What Is at Stake for Women and Babies? New York. http://transform.childbirthconnection.org/reports/cesarean/

Declercq, E., Sakala, C., Corry, M. P., & Applebaum, S. (2006). Listening to Mothers II:  Report of the Second National U.S. Survey of Women’s Childbearing Experiences. New York: Childbirth Connection. http://childbirthconnection.org/pdfs/LTMII_report.pdf

Goer, H., & Romano, Amy. (2012). Optimal Care in Childbirth: The Case for a Physiologic Approach. Seattle: Classic Day Publishing.

Liston, R., Sawchuck, D., & Young, D. (2007). Fetal health surveillance: antepartum and intrapartum consensus guideline. J Obstet Gynaecol Can, 29(9 Suppl 4), S3-56. http://www.sogc.org/guidelines/documents/gui197CPG0709r.pdf

National Collaborating Centre for Women’s and Children’s Health. (2007). Intrapartum care. Care of healthy women and their babies during childbirth. London: NICE. http://www.nice.org.uk/nicemedia/live/11837/36275/36275.pdf

Shy, K. K., Luthy, D. A., Bennett, F. C., Whitfield, M., Larson, E. B., van Belle, G., . . . Stenchever, M. A. (1990). Effects of electronic fetal-heart-rate monitoring, as compared with periodic auscultation, on the neurologic development of premature infants. N Engl J Med, 322(9), 588-593. http://www.ncbi.nlm.nih.gov/pubmed/2406602?dopt=Citation

 

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  1. September 3rd, 2013 at 16:19 | #1

    Thank you for this article, Lamaze International and Henci. I hope you will consider a separate article specific to the “admission strip,” which a Cochrane Review also does not support. Women in our area don’t seem to have much trouble negotiating intermittent auscultation for most of labor, but that admission strip seems to be all but unavoidable, despite the evidence of lack of benefit and potential harm.

  2. avatar
    mrsculpepper
    September 3rd, 2013 at 20:28 | #2

    I wish they had addressed the “admission strip” that’s done pretty much routinely, even where continuous monitoring isn’t practiced.

  3. September 4th, 2013 at 00:26 | #3

    Thanks for this article. I think the trouble is a numbers and technology dominated society which puts more faith in the output of a machine printout than it does in observations recorded by a human being (a midwife). In the UK it seems to be the lawyers and the Clinical Negligence Scheme for Trusts who want unassailable documentary evidence of the progress of labour. It is truly ironic that tethering a woman to bed for monitoring has such an adverse effect on the quality of contractions and the progress of the fetus through the pelvis. Why cannot all those so in favour of technology make use of remote wireless monitoring? There must be enough money in it for some company to make a killing – but apparently such monitors are vastly more expensive than the 1970s machines. Please can someone with a techie minded friend please invent a piece of kit to convert a wired fetal monitor to wireless?

  4. September 4th, 2013 at 08:31 | #4

    I just e-mailed Sharon Muza, who is responsible for S&S, and she gave me the go-ahead to do a post on admission strips. It’ll be a few weeks, though, because I’ve got a couple of projects that have deadlines coming ahead of it. Thanks to both of you for the suggestion.

    @Jessica: Where are you? I’m pleased but stunned to read that women in your area don’t have trouble negotiating intermittent auscultation in your area.

  5. September 7th, 2013 at 09:27 | #5

    @Margaret
    The ironic thing about the use of electronic fetal monitoring as a protection against malpractice suits is that it has the opposite effect. Commenting on malpractice suits arising from brain injury, a Lancet editorialist wrote in 1989: “In light of the evidence . . . , the continued willingness of doctors to reinforce the fable that intrapartum care is an important determinant of cerebral palsy can only be regarded as shooting the specialty of obstetrics in the foot” (p. 1252 http://www.ncbi.nlm.nih.gov/pubmed/2573762?dopt=Citation), and a U.S. reviewer in 1990 observed that a tracing “leaves a permanent record for hindsight interpretation by expert witnesses” (p. 1131 http://www.ncbi.nlm.nih.gov/pubmed/2234724?dopt=Citation) who will claim that mild deviations indicate fetal distress.

  6. December 23rd, 2013 at 11:30 | #6

    Thank you for a very good summary of the evidence which seems to go against some of the logic “detect intrapartum hypoxia early enough and with appropriate action reduce the long term damage”.
    Another explanation for the CTG being ineffective is that there is another routine factor which is fogging the issue. One common feature of an abnormal CTG is bradycardia. Bradycardia is both a sign of fetal hypoxia and a cause of reduced cerebral fetal/neonatal circulation. What happens if the cerebral circulation falls below a critical level in a child or adult ? They lose consciousness, lose all muscle tone and response and look quite pale. Does this sound like a baby with an Apgar of 2 to 4 ? But this baby may not have had any significant intrapartum hypoxia and its low Apgar may be entirely iatrogenic from early cord clamping. This was shown nicely in neonates by Brady et al in 1962 and more recently confirmed by Bhatt et al in the Journal of Physiology from work carried out in lambs in Stuart Hooper’s lab in Melbourne. Before we realised all the babies in Dawsons’s series had early cord clamping, we thought the bradycardia at birth was normal, acceptable and physiological. This bradycardia does not occur in babies with a physiological transition.

    A vasovagal attack occurs when there a failure of preload of the heart, either due to pooling of blood in the leg venous system or from hypovolaemia and consciousness may be lost. Therefore if the bradycardia and hypoovolaemia is severe enough, some of these babies will lose consciousness and become limp, unresponsive and pale, together with a slow heart rate. All the features of a “flat” baby from hypoxia in labour. These babies will need ventilatory assistance (resuscitation) to recover. This insult of bradycardia and hypovolaemia will be a further insult to those babies who have had intrapartum hypoxia. The failure of a reduction in cerebral palsy and perinatal mortality may therefore be largely a result of the unnecessary and iatrogenic intervention of early cord clamping which is known to result in a variable degree of hypovolaemia and bradycardia. Ventilation of a neonate is perfectly possible with the cord and placental circulation intact right by the mother.
    http://journals.cambridge.org/repo_A9011OtS
    Not only is there the loss of blood volume there is the loss of stem cells which may be critical to effect early repair to brain tissue. Autologous cord blood stem cells are being used experimentally to try to treat HIE, a common precurser of cerebral palsy.

    References
    Brady JP, James LS. Heart rate changes in the fetus and newborn infant during labor, delivery, and the immediate neonatal period. Am J Obstet Gynecol 1962;84:1–12

    Bhatt S, Alison BJ,Wallace EM, Crossley KJ, Gill AW, Kluckow M, et al. Delaying cord clamping until ventilation onset improves cardiovascular function at birth in preterm lambs. J Physiol 2013 591(Pt8): 2113–26.

    Dawson JA, Kamlin COF, Wong C, te Pas AB, Vento M, Cole TJ, et al. Changes in heart rate in the
    first minutes after birth. Arch Dis Child Fetal Neonatal Ed 2010 95: F177–81.

    Hutchon DJR. Cutting the Cord: an International Conference INFANT; 2013 9(5): 162.

  7. December 25th, 2013 at 09:52 | #7

    Thank you for your commentary. I am aware of the problems with early cord clamping that you summarize here. Amy Romano and I cover them in the chapter on newborn transition in *Optimal Care in Childbirth: The Case for a Physiologic Approach*. Your review, which I downloaded, will make a nice addition when we come to update the book.

    There is another fundamental problem with fetal monitoring as well. For it to work, there must be tight links between abnormal fetal heart rate patterns and hypoxic symptoms at birth such as low Apgar score or low blood pH and between hypoxic symptoms and permanent brain injury or death, but studies show no more than weak connections. If the link between nonreassuring fetal heart rate patterns and acidemia or low Apgar score is weak, and the link between those symptoms and brain injury is weak, then the connection between nonreassuring fetal heart rate patterns and long-term outcome is nearly nonexistent. And so it has proved, as we document in our book as well.

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