In the years leading into my PhD I started reading everything that had been published about intrapartum CTG monitoring. (It may come as no surprise that there’s quite a lot!) One of the messages that ran strongly through the literature, beginning back in the 1970s with the first randomised controlled trials, was the belief that if we just tried harder then intrapartum CTG monitoring would actually do what it has been designed to do – that is, it would result in a fall in perinatal mortality and hypoxic injury to babies. Often the suggestion was that if people were just a bit smarter then CTG monitoring would work properly.
Schifrin, B. (1984). Letter to the editor. Journal of Law and Medicine, 10(4), 464.
“There is little doubt that bad monitoring is worse than none at all, and that ominous patterns may be overlooked. This litany of deficiencies is a problem of education, not of the potential usefulness of the monitor.”
Another argument that continues to persist is that the addition of more technology will mean that CTG technology can at last blossom as was planned all along. This was essentially the line of argument taken by authors Knupp, Andrews and Tita (2020) in their recent review of the future of electronic fetal monitoring. They examined the following approaches:
• Standardised interpretation guidelines, noting that “any improvements as a result of these standardisations remain to be demonstrated”,
• Fetal stimulation which can provide reassurance of normal fetal oxygenation but has never been assessed with respect to whether this improves perinatal outcomes,
• Fetal scalp blood sampling which “has not been effectively demonstrated to reduce operative deliveries or long-term perinatal outcomes”,
• Fetal echocardiogram ST segment analysis also showed no benefit in perinatal outcomes, and
• Fetal pulse oximetry “did not reduce the caesarean section rate or improve perinatal outcomes”.
They go on to describe two new monitoring systems:
• the Monica Novii which detects the fetal electrocardiogram from a sensor placed on the woman’s abdomen, and records electromyogram signals to detect uterine tone rather than an external or internal pressure sensor, and the
• the Moyo a wearable fetal heart rate monitor which uses Doppler to record the fetal heart. No uterine tone measurement is incorporated.
Neither system has been been adequately investigated to determine if it offers advantages over intermittent auscultation
They also explore the evidence for computerised interpretation of the CTG. This gets back to the “if people were just smarter” issue, as it assumes that a computer will consistently and accurately interpret the CTG every time, eliminating the problem of variable or incorrect CTG interpretation. To date none of these computer interpretation systems have “been definitively demonstrated to improve pregnancy outcomes”. This undermines the argument that eliminating interpretation errors will suddenly make CTG monitoring work. Despite the evidence to date, the authors remain buoyantly hopeful that “prediction of pregnancies that may be destined to end in acidaemia or caesarean delivery with a high degree of accuracy can lead to early intervention and help prevent other indirect complications such as those related to prolonged labour”.
Perhaps one day I’ll be proven wrong, but I simply can’t see how after 6o years of proof that the CTG can’t save babies from harm that a do-dad to plug into the monitor, an education course, or a standardised guideline will now make CTG monitoring effective. Perhaps it is time we realised that the thinking that went into the creation of CTG monitoring was itself fundamentally flawed. If we had abandoned CTGs in the mid 80s when the bulk of the randomised controlled trials were available we would have had 35 years of time during which me might have come up with a solution that actually works. Let’s not waste more decades before getting started.
Knupp, R. J., Andrews, W. W., & Tita, A. T. N. (2020). The Future of Electronic Fetal Monitoring. Best Practice & Research Clinical Obstetrics & Gynaecology. https://doi.org/10.1016/j.bpobgyn.2020.02.004