Is continuous electronic fetal monitoring useful for all women in labour?
BMJ 2017; 359 doi: https://doi.org/10.1136/bmj.j5423 (Published 05 December 2017) Cite this as: BMJ 2017;359:j5423
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As we approach the third decade of the 21st century the debate goes on; to detect hypoxia in labour, should a baby’s well-being still be monitored with a monoaural stethoscope designed in the 19th century, measuring one variable, the heart rate, for 4 minutes in every hour? The evidence suggests it should if the pregnancy is classed as low risk (1). Evidence from the late 20th century showed that using Intermittent Auscultation (IA) in labour, there was no difference in the rate of asphyxia, and caesarean section rates were lower, compared to continuous Electronic Fetal Monitoring (cEFM). This evidence has justified the continued use of IA in low risk patients (1). This strategy reduces the risk of avoidable harm and unnecessary intervention in a physiological process. Has this practice made birth safer?
Maternity services have never been safer (2). However, in 2016/2017 in the NHS, obstetrics had the third highest numbers of claims for compensation, behind orthopaedics and A&E. The value of compensation claims for obstetrics alone was equal to the value of claims for all the other specialities in the NHS combined (3). This might be expected as babies born with poor outcomes require lifelong care. However, in 2015 the Each Baby Counts programme, run by the Royal College of Obstetricians and Gynaecologists, found that 76% of term, normally formed babies that suffered intrapartum stillbirths, early neonatal deaths and severe brain injury would have had a different outcome with different care (4). The 2017 MBRRACE-UK Perinatal Confidential Enquiry Term, singleton, intrapartum stillbirth and intrapartum-related neonatal death showed that in 80% of intrapartum stillbirths, different care might have prevented the death (5). A recent review of claims for cerebral palsy by NHS Resolution in 2017 concluded very little had changed in the last 20 to 25 years (3). The same mistakes were being made and lessons had not been learned as most cases were avoidable. An earlier review of maternity claims from 2000 to 2010 by the NHS Litigation Authority made the same observation (6). The Each Baby Counts review showed errors with risk assessment in pregnancy and labour was common. Finally, the 2015 Morecambe Bay Review showed mothers and babies were harmed because of a desire to reduce intervention and increase normal births (7). With these unjustifiable levels of avoidable harm, it is hard to justify IA on the grounds it reduces the risk of unnecessary harm. Much greater harm is caused now by too little intervention, applied too late.
The RCOG Each Baby Counts programme set an aspiration to ensure no normally formed baby at term suffers intra-partum stillbirth, early neonatal death or severe brain injury at birth. Is this feasible? The high chance of a safe birth outcome after a poor outcome in the previous birth shows we know how to make birth safe in the 21st century when we choose to. In a baby classed as high risk, safety is given top priority. The baby will be monitored with cEFM. The healthcare professionals looking after the baby will more likely detect hypoxia early using cEFM. This is despite the evidence that cEFM is poor at detecting hypoxia. cEFM is a screening tool, but used properly can help achieve a hypoxia-free birth. The NHS Resolution Cerebral Palsy review showed healthcare professionals made the same known predictable, avoidable and repeatable mistakes with CTG interpretation (3). To ensure the baby is born safely, all the carers must do is avoid making those same predictable and avoidable mistakes. The primary aim of care in labour is to achieve a hypoxia-free birth which is possible in the 21st century.
Some would defend maintaining the status quo until there is new evidence that changing current practice would make birth safer (1). Unfortunately, the current evidence leaves out the views and expectations of the most critical group in any birth: the parents. Parents in the 21st century are better informed, expect a safe birth and have a much lower level of tolerance for things to go wrong. They are less likely to accept poor outcomes without question or without accountability. The recent seismic changes in the safety agenda in obstetrics in the United Kingdom has largely been driven by parents whose babies have suffered avoidable harm (8). In 2018, the days when healthcare professionals can hide behind evidence, bureaucratic systems and the law to avoid transparency or accountability and rationalise avoidable harm are numbered. The stories on the Each Baby Counts website show why we cannot go on causing avoidable harm in birth (9). Joshua’s Story by James Titcombe (10) is essential reading for evidence of the human cost of losing a baby from avoidable harm and the systemic obstacles parents face in search of the truth. With a system that causes up to 80% avoidable and predictable harm during birth, doing more of the same is clinically, ethically and morally indefensible.
So, should low risk mothers be monitored with cEFM? When discussing labour, do carers inform mothers a reliable accurate risk assessment cannot be guaranteed? Or that their baby will be monitored for one minute every 15 minutes? Or that antenatal fetal risk assessment is based on symphysio-fundal height measurement which is no better than abdominal palpation. Symphysio-fundal height measurement has a low sensitivity for detecting fetal growth restriction, a major predictor of poor fetal outcome (11). This means some high risk babies will be not be monitored with cEFM when they should, possibly resulting in a poor birth outcome. With such uncertainty and variation in care, should the choice of fetal monitoring still be made just by healthcare professionals? In the age of personalised care, mothers’ autonomy and choice, should we not ask mothers after an unbiased discussion, irrespective of their risk status, how they would like their babies monitored? If the mother chooses to have her baby monitored with cEFM, and her carers competently utilise cEFM avoiding predictable and avoidable errors, she can be reassured of the best outcome for her baby: a baby born without hypoxia. In the 21st century, is there any excuse to monitor any baby any other way?
1. Is continuous electronic fetal monitoring useful for all women in labour? BMJ 2017;359:j5423
2. Saving Babies’ Lives: A care bundle for reducing stillbirth, NHS England 2016.
3. Five years of cerebral palsy claims: A thematic review of NHSR data. M Magro 2017
4. Each Baby Counts 2015 Full Report. RCOG 2017.
5. MBRRACE-UK Perinatal Confidential Enquiry Term, singleton, intrapartum stillbirth and intrapartum-related neonatal death 2017
6. Ten Years of Maternity Claims: An Analysis of NHS Litigation Authority Data. NHS Litigation Authority 2012
7. The Report of the Morecambe Bay Investigation March 2015. B Kirkup 2015.
8. Maternity Safety Strategy. House of Commons Hansard. Vol 632. 28 November 2017.
9. www.rcog.org.uk/en/guidelines-research-services/audit-quality-improvemen...
10. Joshua’s Story - Uncovering the Morecambe Bay NHS Scandal. James Titcombe 2015.
11. The Investigation and Management of the Small–for–Gestational–Age Fetus. Green–top Guideline No. 31 2013
Competing interests: No competing interests
Trying to make sense of whether continuous intrapartum monitoring of fetal heart rate and uterine contractions confers net benefit to the infant-to-be is nothing new, as the other responses make clear. One of the problems is that fetal monitoring generally does more to the mother-fetus unit than simply extracting data. The machinery itself changes the dynamics of what goes on in the room. For a variety of reasons, both physical and psychological, being attached to a bed-side machine, encourages the mother to take to the bed. This undoubtedly has anatomical and physiological consequences such as reduction of maternal venous return due to IVC compression. What is in doubt is the extent and significance of these effects in comparison to the benefits attributable to the monitoring itself.
In 1983 we reported on a non-invasive fetal monitoring system that used radio-telemetry to free the mother from being attached to anything more than a small box that she could carry in a pocket. The technology was crude by today’s standards and we found that signal quality was highly dependent on maternal physical build. These limitations should be quite amenable to modern technology. Perhaps it is time to revisit this idea.
Albert, D.J. and Terry, H.J., 1983. Non-invasive fetal monitoring using radiotelemetry. Clinical Physics and Physiological Measurement, 4(3), p.291.
Buchan, P.C., Tyndale-Biscoe, S., Albert, D.J., Terry, H.J. and Bromham, D.R., 1987. Two non-invasive telemetry fetal monitoring systems. The effect of maternal build on trace quality. Journal of Obstetrics and Gynaecology, 8(1), pp.9-11.
Competing interests: The project described here was part funded by the Medical Research Council and the NHS.
It has been said that "science is (much) cognition, not (just) empiricism" [1]. Any experiments/clinical trials need to be preceded and followed by critical thinking.
"INFANT" trial and its limitations:
It would be incorrect to consider the results of INFANT trial to suggest a failure of cardiotocography (CTG) itself [2]. It did not test CTG versus intermittent auscultation (IA) or no auscultation. The INFANT trial had a major flaw of “learning in the control group” [3] which makes its conclusions unreliable. The main counterargument offered by Brocklehurst et al is that this major flaw was compensated by a key part of their hypothesis that some individuals have “intrinsic pattern-recognition inability” not improved by training [1,3]. This is at best questionable because any intrinsic "pattern-recognition inability” would not be applicable to the large majority of clinicians or to computerised support. Most importantly, the INFANT trial shows that the lack of improvement in perinatal outcomes was not due to failure to identify fetal heart rate (FHR) abnormalities on CTG; but was due to failure to take appropriate management decisions once the CTG abnormalities were recognised. The key question seems why the “system” (current CTG interpretation) fails even though it does identify abnormal CTGs? Does it create a lot of background noise (excessive false positives leading to confusion or false alarm fatigue) making it very difficult to separate wheat from the chaff and intervene appropriately in time? Hence, it becomes very important to critically examine the elements of CTG interpretation framework itself rather than assuming that there are no significant improvements are possible.
The enigma of evidence for cardiotocography:
The previous studies on CTG are dominated by flaws like variations in design, differences in CTG interpretation frameworks, great rarity of important outcomes further distorted by “intervention effect” and different interpretations of FHR parameters most crucially the FHR decelerations [4]. Thus CTG comes very close to the category of problems that can’t be entirely solved by statistics alone because the noise/confounding is so large or the signal is very small or the question is fundamentally unanswerable with statistics [5]. The Cochrane review is a testament to this and states that most studies were low or very low-quality evidence and downgraded for limitations in design, inconsistency and imprecision of results [6]. In contrast, the obstetricians and midwives regularly come across CTG saving lives and preventing neonatal morbidity in their day to day practice – the so called “Interocular Trauma Test (IOT)” where the observations / conclusions hit you in the middle of your eyes. The CTG does make a contribution (relatively small) to the overall rise in caesarean section rate; but most clinicians and patients seem to place this harm in a different context/ balance while weighing effects of serious birth asphyxia. Effective alternatives to CTG are unlikely in foreseeable future. Not only these technologies have to be minimally invasive, economical and suitable for mass application; but they will have to be proven to be effective (compared against of course CTG). In addition, these will suffer the very similar problems that bedevil attempts to "prove" the benefits of CTG by mainly quantitative approach. This seems the main reason why computerised CTG interpretation has not caught on despite exponential increase in computer power in last two decades.
Is the current CTG pattern-recognition wrong?
The disillusionment with CTG has reached a crisis point on both sides of Atlantic with misguided calls to abandon it. Remarkably, looking back there was hardly any crisis in the traditional British system of CTG interpretation from 1970s to 2007 with no discordance or clamour for change. The crisis seems to have been imported by a radical change in categorisation of FHR decelerations in 2007 [4]. Thomas Kuhn revolutionised the understanding of scientific progress by claiming that the scientific fields undergo periodic "paradigm shifts" rather than solely progressing in a slow linear and continuous way. In 2007 the British system of CTG interpretation seems to have made a key paradigm shift (but in the wrong direction, probably for the first time in science) by adopting a fundamentally flawed concept that the vast majority of FHR decelerations are because of cord-compression and hence must be called "variable"; and that "early" decelerations due to head-compression are extremely rare [4]. Many maternity units immediately observed a great increase in CTGs categorised as suspicious/pathological, midwives calling obstetricians with greatly increased frequency and paradoxically at the same time some increase in babies born with birth asphyxia. Over the last decade, an inertia and helplessness has set in as clinicians come to terms with this new mistaken norm. No wonder many senior obstetric consultants admit to continue to use in their heads the old pre-2007 pattern-recognition of FHR decelerations, a dispensation not afforded to midwives and junior obstetricians. The new generation of obstetricians and midwives are growing up knowing only the wrong pattern-recognition and hence they will not acquire the so called "art" of CTG interpretation which most in the older generation were fortunate to acquire.
Interestingly, the concept that vast majority of FHR decelerations are due to cord-compression came from empiricism divorced with critical analysis (cognition). Experiments involving clamping of umbilical cord in sheep fetuses produced "rapid" decelerations; hence all rapid decelerations were claimed to be because of cord-compression and must be called "variable" even if consistently early in timing. after more than a decade of such insistence some of these scientists have now come around to accept that this was indeed unscientific and a misconception [7]. Surprisingly, there is still a customary excuse that even if fetal head compression also causes rapid decelerations, these must now be called variable "by definition"; or it does not matter what label we give to FHR decelerations! Aren't we are talking of the most important pattern-recognition in CTG interpretation as FHR decelerations are centre-stage [4]? Even more importantly, if a theory is disproven (falsified) then it is a scientific imperative to cast it away (Sir Karl Popper). It seems precisely the unscientific pattern-recognition of FHR decelerations which creates a lot of background noise (false positives leading to confusion or false alarm fatigue) making it very difficult for clinicians to take decision of timely intervention. Thomas Kuhn made another important observation that "The route from hypothesis (theory) to law (system / framework) to measurement (studies/trials) can almost never be travelled backwards". Thus, any number of clinical trials are not going to prove or correct the fundamental fallacies in pattern-definitions of FHR decelerations.
As discussed earlier, electronic fetal monitoring or CTG is a hard (but not impossible) nut to crack with conventional EBM. A good solution seems not to ignore the gradual evolution of a CTG interpretation system underpinned by scientific hypotheses subjected to clinical practice over many years but take it as a default system. The British experience had evolved from 1970s to categorise the FHR decelerations confined to contractions (majority) as “early” based on observations of pioneers like Hon and the group of Caldeyro-Barcia (Type I, II and III). Most importantly, the primarily “timing-based” classification of FHR decelerations has a major advantage that it distinguishes between benign early decelerations and pathological late decelerations from increasing hypoxaemia of whatever aetiology viz drop in uteroplacental perfusion, cord-compression or purported (unproven) cerebral ischemia [4].
Conclusion
Science is (much) cognition and not (just) empiricism. CTG is likely to remain a widely practiced technique in developed countries against which all other technologies will be judged. FHR decelerations are the most important clue to fetal acidaemia and the theory that the vast majority of FHR decelerations are due to cord-compression has been disproven and should be cast away [4].
Declaration of interest: The author has no conflict of interest to declare. The views expressed are opinion only.
Dr Shashikant L Sholapurkar, MD, DNB, MRCOG
Obstetrician and Gynaecologist, Royal United Hospital, Bath, UK
s.sholapurkar@nhs.net
References
1. Bookstein FL. “Numbers and reasons” —core elements of numerical inference techniques today, with implications for the rhetoric of LASR presentations. https://www1.maths.leeds.ac.uk/statistics/workshop/lasr2010/proceedings/...
2. INFANT Collaborative Group. Computerised interpretation of fetal heart rate during labour (INFANT): a randomised controlled trial. Lancet 2017; 389:1719–1729. doi: 10.1016/S0140-6736(17)30568-8.
3. Brocklehurst P, Field DJ, Juszczak E, Kenyon S, Linsell L, Newburn M et al. The INFANT trial. Lancet 2017;390:28.
4. Sholapurkar SL. Critical Imperative for the Reform of British Interpretation of Fetal Heart Rate Decelerations: Analysis of FIGO and NICE Guidelines, Post-Truth Foundations, Cognitive Fallacies, Myths and Occam’s Razor. J Clin Med Res. 2017; 9: 253-65.
5. Simmering J. Inter-ocular trauma test. http://jacobsimmering.com/2016/11/17/uhTickets/
6. Alfirevic Z, Devane D, Gyte GML, Cuthbert A. Continuous cardiotocography (CTG) as a form of electronic fetalmonitoring (EFM) for fetal assessment during labour. Cochrane Database of Systematic Reviews 2017, Issue 2. Art. No.: CD006066. DOI: 10.1002/14651858.CD006066.pub3.
7. Lear CA, Galinsky R, Wassink G, Yamaguchi K, Davidson JO, Westgate JA, Bennet L & Gunn AJ. The myths and physiology surrounding intrapartum decelerations: the critical role of the peripheral chemoreflex. J Physiol 2016; 594: 4711-25.
Competing interests: No competing interests
Every now and again someone reviews the randomised trials comparing continuous electronic fetal monitoring (cEFM) with intermittent auscultation (IA) and concludes that the former does little or no good, probably increases Caesareans, so should be dropped.
But neither cEFM nor IA ever saved a baby or harmed a mother directly; both are tests. What saves (or harms) the baby or mother is expedited delivery by Caesarean or instrument, tocolysis, intravenous fluids, oxygen, or one of the other therapies in the obstetricians’ armamentarium.
This is why the trials of cEFM v IA, even the beautifully conducted Dublin trial (Macdonald et al. 1985) led by the late Adrian Grant, are difficult to interpret. None of the trial protocols specified how obstetricians and midwives were supposed to respond to the various heart rate patterns in the cEFM group. It was just assumed that they knew what to do. Even today there is debate about the cEFM criteria for intervention; in the last four years NICE alone has produced three different sets of guidelines for intra-partum fetal monitoring (NICE 2007, 2014, 2017). The criteria for expediting delivery after IA have not been defined to this day.
In the absence of a trial of “cEFM following 2017 NICE guidelines for delivery” versus “IA following an agreed set of IA guidelines for delivery”, those of us who actually look after women in labour have to decide what to do on the basis of non-randomised trial evidence. There is a fair bit of it.
Babies die in labour. The day you are born is by a factor of many hundreds the most dangerous day of your life until you reach old age (Walker et al. 2014). Even in well-organised developed countries today, about 1 in 2,000 babies die in labour. Without any modern care the rate might be as high as 50 per thousand (Kaunitz et al. 1984). The cause is usually gradually increasing hypoxia due to poor fetal glycaemic reserves at the start of labour, a long labour, over active contractions, or a combination of all three. Prior to death in such circumstances the fetal heart rate changes follow well-described patterns; a rising baseline rate, loss of accelerations in response to contractions and movement, reduced baseline variability, decelerations of various sorts, and finally a terminal bradycardia. These were observed in animal models of intrauterine fetal hypoxaemia many years ago (Dawes et al. 1964, 1968, and 1969, Boddy et al 1974) and surely apply to human births.
Unfortunately human studies of how different fetal heart rate patterns predict hypoxia, death or brain damage are difficult to interpret. Experimental induction of hypoxia is obviously unethical, and observational studies are confused by the interventions mandated by detection of significant abnormality. The recent NICE guideline’s many hundreds of pages of appendices, supposedly showing poor likelihood ratios for various heart rate features predicting these outcomes, are misleading. In most cases the doctors delivered the baby, administered tocolysis, or stopped oxytocin in response to the heart rate abnormality and prevented the very event it was predicting.
There are also secular trends, before and after studies, and non-randomised contemporaneous comparative ones. Over the forty years or so since cEFM was introduced, intra-partum death rates fell steadily. When my colleagues and I reviewed the non-randomised evidence (Hornbuckle et al. 2000) we found that 12/13 studies comparing periods before and after either introduction or expansion of cEFM, showed a reduction in intra-partum deaths, and 9/9 contemporaneous non-randomised studies comparing cEFM with IA monitored births, showed lower intra-partum deaths with the former. Cerebral palsy rates did not fall with the first 30 years or so of cEFM, perhaps because relatively few cases are caused by intra-partum hypoxaemia. But over the last 10 years or so, as formal training in interpretation of cEFM has become widespread, even cerebral palsy rates have begun to fall (Reid et al 2016). Correlation does not prove causation, and observational studies may be biased in all sorts of ways, but in light of what we know about physiology, the evidence, at least for intra-partum death, is supportive.
No-one seriously contends that we should not monitor the fetal heart rate in labour. The issue is should we monitor it continuously with an ultrasound device that gives a clear and permanent record of the baseline rate, variability, accelerations and decelerations, or ask the midwife to use a plastic trumpet every 15 minutes or so, to measure the average rate only. Anyone who has tried doing the latter in late labour, the period when the baby is most at risk, in a woman without an epidural, knows how difficult it is. In high risk pregnancies it should be as unthinkable to rely on intermittent auscultation as it would be for adult intensive care units to go back to intermittent palpation of the pulse.
Among low risk pregnancies some people argue that the chance of the baby dying intra-partum is relatively low, and Professor Brocklehurst is surely correct that cEFM results in more Caesarean births, many of which with hindsight will turn out to have been unnecessary. Some parents may decide that in that situation IA is sufficient for them. That is their choice.
Jim Thornton. Nottingham. 7 December 2017
References
Macdonald D, Grant A, Sheridan-Pereira M, Boylan P, Chalmers I. The Dublin randomized controlled trial of intrapartum fetal heart rate monitoring. American Journal of Obstetrics and Gynecology 1985;152(5):524-39.
National Institute for Clinical Excellence (2007) Intrapartum care: Care of healthy women and their babies during childbirth Clinical guideline [CG55]
National Institute for Clinical Excellence (2014) Intrapartum care for healthy women and babies Clinical guideline [CG190]
National Institute for Clinical Excellence (2017) Fetal monitoring during labour. Update to Clinical guideline [CG190]
Walker KF, Cohen AL, Walker SH, Allen KM, Baines DL, Thornton JG. The dangers of the day of birth. BJOG 2014; DOI:10.1111/1471-0528.12544.
Kaunitz AM, Spence C, Danielson TS, Rochat RW, Grimes DA. Perinatal and maternal mortality in a religious group avoiding obstetric care. Am J Obstet Gynecol. 1984 Dec 1;150(7):826-31.
Dawes GS, Duncan S, Lewis BV, Merlet C, Owen-Thomas J, Reeves JT. Aortic chemoreceptor function in foetal lambs. J Physiol. 1968 Sep;198(2):109
Dawes GS, Mott JC. Changes in O2 distribution and consumption in foetal lambs with variations in umbilical blood flow. J Physiol. 1964 Apr;170:524-40
Dawes GS, Duncan SL, Lewis BV, Merlet CL, Owen-Thomas JB, Reeves JT. Hypoxaemia and aortic chemoreceptor function in foetal lambs. J Physiol. 1969 Mar;201(1):105-16.
Boddy K, Dawes GS, Fisher R, Pinter S, Robinson JS. Foetal respiratory movements, electrocortical and cardiovascular responses to hypoxaemia and hypercapnia in sheep. J Physiol. 1974 Dec;243(3):599-618.
Hornbuckle, J., Vail, A., Abrams, K. R. and Thornton, J. G. (2000), Bayesian interpretation of trials: the example of intrapartum electronic fetal heart rate monitoring. BJOG: An International Journal of Obstetrics & Gynaecology, 107: 3–10. doi:10.1111/j.1471-0528.2000.tb11571.x
Reid SM, Meehan E, McIntyre S, Goldsmith S, Badawi N, Reddihough DS; Australian Cerebral Palsy Register Group. Temporal trends in cerebral palsy by impairment severity and birth gestation. Dev Med Child Neurol. 2016 Feb;58 Suppl 2:25-35. doi: 10.1111/dmcn.13001
Competing interests: I have been paid to give expert opinions in cases of stillbirth and cerebral palsy allegedly caused by negligence in the interpretation or performance of both intermittent auscultation and continuous electronic fetal heart rate monitoring. I am a practising obstetrician involved in intra-partum care. I chair a weekly review meeting in my Trust, where obstetricians and midwives present and discuss some of the previous week's continuous electronic fetal heart rate traces.
The BMJ must be commended for this timely head-to-head debate, where doctors supporting electronic fetal heart monitoring seem to ‘cherry-pick’ evidence, and the principal investigator of many great obstetric trials including INFANT (a UK RCT involving 47 062 women) (1) explains the uncertainties. Cochrane (2), FIGO (3) and NICE (4) have all admitted there is no evidence that human or computerised interpretation of cardiotocographs (CTG) reduces intrapartum stillbirth and cerebral palsy, but does cause maternal harm. INFANT showed that adding intelligent decision support to costly and demanding CTG technology did not improve clinical outcomes for mothers or babies (1). A previous commentator facing the limits of this monitoring in the prevention of neonatal metabolic academia rebuffed the repetitive call for yet more “improved scientific pattern recognition of fetal heart rate decelerations and use of adjunctive test”, quoting the Institute of Medicine: “Trying harder will not work. Changing systems of care will.” (5)
We propose two new approaches to making care of fetal and neonatal hypoxia simple and cheap rather than complicated and costly with computerized CTG:
First, the assessment of mobile resuscitation devices designed specifically to facilitate newborn resuscitation at the bedside with an intact cord, as separating the newborn from its placental transfusion iatrogenically interferes with ‘auto-resuscitation’.(6) Indeed, timely management of complications is the cornerstone for recovery.
Second, labour use of carbon monoxide (CO) breath analyzers, a simple, cheap, fast and non-invasive technology, to identify the most frequent conditions responsible for hypoxia and metabolic academia: Carboxyhemoglobin (HbCO) due to smoking or underestimated environmental causes (heating systems, motor vehicles etc.). When CO is inspired, fetal HbCO increases more slowly than maternal concentration but can attain twice as high levels and prolonged, low level exposures can result in extremely high tissue concentrations. Tissue hypoxia and direct action on haem-containing proteins (myoglobin,cytochromes) are key mechanisms responsible for CO’s fetal toxicity. Additionally, pulse oximetry is inadequate to detect carbon monoxide poisoning because carboxyhemoglobin can be misinterpreted as oxyhemoglobin.
The over-longstanding reliance on CTG highlights the effect of a rigid mindset but might be related to vested interests from equipment manufacturers and plaintiff lawyers and experts who find lucrative medico-legal practices.
1 The INFANT Collaborative Group. Computerised interpretation of fetal heart rate during labour (INFANT): a randomised controlled trial. Lancet 2017;389:1719-1729
2 Alfirevic Z, Devane D, Gyte GML, Cuthbert A. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database of Systematic Reviews 2017, Issue 2. Art. No.: CD006066. DOI:10.1002/14651858.CD006066.pub3
http://www.cochrane.org/CD006066/PREG_continuous-cardiotocography-ctg-fo...
3 Ayres-de-Campos D, Spong CY, Chandraharan E et al. FIGO consensus guidelines on intrapartum fetal monitoring: Cardiotocography. Int J Gynecol & Obstet 2015;131:13–24.
4 NICE CG190. Intrapartum care for healthy women and babies. 2014. https://www.nice.org.uk/guidance/cg190
5 Clark SL, Hamilton EF, Garite TJ et al. The limits of electronic fetal heart rate monitoring in the prevention of neonatal metabolic acidemia. Am J Obstet Gynecol. 2016;163.e1–163.e6 and Reply. Am J Obstet Gynecol 2017;216:93
6 Weeks AD, Watt P, Hutchon DJR, Yoxall CW, Gallagher A, Bewley S, Odd D, Burleigh A, Fisher T, Heuchan AM, Duley L. Innovation in immediate neonatal care: development of the Bedside Assessment, Stabilisation and Initial Cardiorespiratory Support (BASICS) Trolley BMJ Innov 2015;1:53–58.
Competing interests: SB chaired NICE 2014 Intrapartum Care Guideline Development Group CG190. AB has no link to declare.
This is a very useful debate which I incorporated into my recent HealthWatch Autumn Newsletter article.
https://www.healthwatch-uk.org/news/139-the-autumn-2017-issue-of-the-hea...
Mullins and Lees argue
"Furthermore, intrapartum monitoring would not be expected to reduce the incidence of cerebral palsy because, contrary to widespread belief, it is rarely linked to intrapartum events"
So why are we bothering to try to prevent cerebral palsy (CP) if it is rarely linked to intrapartum events ? This was not what the authors of the Each Baby Counts told us about the failure of the carers to read the CTG accurately. It certainly is a very convenient argument but if CTG monitoring reduces seizures why not CP ?
"Infants of pregnant women at low risk whose labour started in primary care under the supervision of a midwife in the Netherlands had a higher risk of delivery related perinatal death and the same risk of admission to the NICU compared with infants of pregnant women at high risk whose labour started in secondary care under the supervision of an obstetrician."
If the care of women's labour was transferred from the obstetrician to the midwife and the outcome was poor then the midwife would be blamed. But if the midwife transfers care to the obstetrician, it is still the midwife who is to be blamed !!!
"An important limitation of the study is that aggregated data of a large birth registry database were used and adjustment for confounders and clustering was not possible. However, the findings are unexpected and the obstetric care system of the Netherlands needs further evaluation."
If it suited the argument you could easily emphasise the role of the confounders !
I do not have any strong views on the CTG, although logically it should reduce poor outcomes. After 35 years of reading CTGs it is not that easy. But, as I state in the HealthWatch article, no matter how good and timely the action of the obstetrician the outcome will be strongly affected by the care the baby gets immediately after delivery and if the baby gets early cord clamping and as a result has severe hypovolaemia, most will die or get CP. So the obstetrician's good care is lost.
Peter Brocklehurst explains the CTG is a screening test. So what is the difference between a screening test and a diagnostic test ? It is all down to sensitivity and specificity. The CTG has not been found to be sensitive or specific enough for the outcomes of CP and death. But is this down to the subsequent care of early cord clamping ? Can Peter tell me what test in labour is diagnostic for outcome of CP or death ? I do not know of any !!!
Competing interests: No competing interests
CTG debate from a junior registrar's perspective. Re: Is continuous electronic fetal monitoring useful for all women in labour?(1)
There is a big leap in responsibilities from obstetric SHO to registrar and this includes making decisions of when intervention is required in intrapartum care. The majority of doctors and patients want a normal vaginal delivery but first and foremost, a healthy baby and mother. This key decision is often guided with the help of an intrapartum CTG. The difficulty with this is first our own personal interpretation but then, often with the help of hindsight, others interpretations. Any doctor who has worked on labour ward will have seen normal CTGs where the baby has been born in poor condition and horrendous looking CTGs that have resulted in a category 1 caesarean where they have come out screaming their lungs off. These experiences only make the situation more difficult when we suddenly graduate to being by ourselves on labour ward and we have a CTG that doesn't really fit into any of the boxes. The third part of CTGs that scares me is when consultants make comments that they still use the old (pre 2007) classification of CTGs. In the three years I have been a Obstetrics and Gynaecology trainee, I have had new CTG guidelines to get used to. In part due to going to a district general which uses STAN but NICE and FIGO have both bought out new guidelines in this time. I do wonder if my interpretation of decelerations is now a compilation of all the recent changes.
In modern day medicine, we often like to be able to quantify investigations and have set protocols. CTGs have been categorized into different boxes over the years (5 changes in 10years) to allow us to feel confident that our decisions about intrapartum care are evidenced based. But should CTGs be classified at all? ECGs do not undergo the same level of scrutiny. NICE and FIGO, who regularly review their guidelines, have changed their classifications regularly and there are disparities between the two. When reviewing the studies, the sensitivities of CTG classifications and fetal outcomes (when defined by umbilical cord pHs, APGARs, neonatal seizures or encephalopathy) are low [2-7] . The quality of studies used in the Cochrane review as evidence for the most recent NICE guideline CTG changes has been described as "low or very low" [8]. When the CTG was first introduced in the 1970s, it was thought it would have a huge impact on reducing cerebral palsy. But over the years it has been shown that this in fact has not been the case [9,10]. A retrospective study, by Kundu S et al, published in November 2017 showed that there was large intra- and interobserver variability when trying to predict umbilical artery pH from CTGs [11]. In fact this can be extrapolated that our current interpretation of CTGs is poor. Kundu did suggest that "clinical experience and the collaboration and consultation within the whole team" is key. The difficulty is that there are so many confounding factors when CTGs are reviewed and how are the more junior members meant to feel confident with their decision making, when the CTG interpretation keeps changing?
It seems that CTG guidelines keep being changed, still using relatively poor evidence, making all variety of patterns fit into just three boxes and is associated with a high false positive rate. So should we first get the facts right to develop a good prognostic tool and then and only then start debating if we should be using CTGs in low as well as high risk labours?
No competing interests.
References:
1. Is continuous electronic fetal monitoring useful for all women in labour? BMJ 2017;359:j5423.
2. Grant A, O'Brien N, Joy MT, Hennessy E, MacDonald D. Cerebral palsy among children born during the Dublin randomised trial of intrapartum monitoring. Lancet. 1989;2:1233.
3. Kelso IM, Parsons RJ, Lawrence GF, Arora SS, Edmonds DK, Cooke ID. An assessment of continuous fetal heart rate monitoring in labor. A randomized trial. American Journal of Obstetrics and Gynecology. 1978;131:526–532.
4. Leveno KJ, Cunningham FG, Nelson S, Roark M, Williams ML, Guzick D, Dowling S, Rosenfeld CR, Buckley A. A prospective comparison of selective and universal electronic fetal monitoring in 34,995 pregnancies. New England Journal of Medicine,N Engl J Med. 1986;315:615–619.
5. MacDonald D, Grant A, Sheridan-Pereira M, Boylan P, Chalmers I. The Dublin randomized controlled trial of intrapartum fetal heart rate monitoring. American Journal of Obstetrics and Gynecology. 1985;152:524–539.
6. Vintzileos AM, Antsaklis A, Varvarigos I, Papas C, Sofatzis I, Montgomery JT. A randomized trial of intrapartum electronic fetal heart rate monitoring versus intermittent auscultation. Obstetrics and Gynecology. 1993;81:899–907.
7. Wood C, Renou P, Oats J, Farrell E, Beischer N, Anderson I. A controlled trial of fetal heart rate monitoring in a low-risk obstetric population. American Journal of Obstetrics and Gynecology. 1981;141:527–534.
8. Alfirevic Z, Devane D, Gyte GML, Cuthbert A. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database Syst Rev2017;2:CD006066.
9. Lees C. Most cases of cerebral palsy are associated with antenatal events. BMJ2017;356:j834.
10. Nelson KB, Sartwelle TP, Rouse DJ. Electronic fetal monitoring, cerebral palsy, and caesarean section: assumptions versus evidence. BMJ2016;356:i6405.
11. Kundu S.; Kuehnle E.; Schippert C.; von Ehr J.; Hillemanns P.; Staboulidou I. Estimation of neonatal outcome artery pH value according to CTG interpretation of the last 60 min before delivery: a retrospective study. Can the outcome pH value be predicted? Archives of Gynecology and Obstetrics. 296 (5) (pp 897-905), 2017. Date of Publication: 01 Nov 2017.
Competing interests: No competing interests