Cardiotocography, Intermittent Auscultation and Cerebral Palsy Litigation
The article by Nelson et al 1 is a wake-up call for obstetricians and their professional organisations. Despite spending large sums of money for cerebral palsy (CP) litigation, the compensation remains a lottery for the sufferers.
CTG and Evidence based Medicine
Cardiotocography (CTG) has a 99.8% false positive rate in predicting CP, a very rare event. But, it is quite late to intervene when CP becomes a real and present danger. The main goal of CTG is to prevent birth asphyxia, potentially dangerous fetal acidaemia (pH <7.10 and base deficit >12 mEq/L) and hypoxic-ischemic-encephalopathy (HIE). For this, a false positive predictive value of 'abnormal' CTG of around 70% seems likely, reduced further by fetal scalp blood sampling. Although unproven, the practical experience of British Obstetricians in the past was not far from this.
A survey was conducted of the personal preferences of clinicians in our Institute with an existing liberal culture of “intermittent auscultation (IA) of fetal heart rate (FHR)”. They were reminded of the evidence that CTG is not reliable in preventing CP or intrapartum hypoxia even in the presence of risk factors but does increase operative delivery. All 14 Obstetricians and 11 out of 15 midwives still chose to have CTG for themselves or their partners in the presence of any risk factors. Thus, there seems a disconnect between the “evidence” and the beliefs/experience of birth-attendants themselves. Secondly, they seem to judge any harm from CTG in a different context/balance.
The limitations of evidence based medicine have been well described. 2,3 Although the gold standard,, systematic studies have failed to show a significant benefit from intrapartum CTG for several reasons.3 However, birth attendants have regularly observed in actual practice that CTG prevents birth asphyxia. CTG will remain a widely practised procedure in the near future despite mistakes and variability in interpretation. CTG abnormalities make a small contribution to overall increasing caesarean section rate. In fact in developing countries like Brazil and China (where CP litigation is very rare), the caesarean rate is two to three times that in developed countries.
The meta-analysis of randomised controlled trials (RCTs) of CTG versus IA is underpowered to show a small difference. Most studies were done in the USA, where the categorisation of FHR decelerations (centre-stage in interpretation) may have been inconsistent compared to the British practice before 2007. 4 Moreover, if IA suggests abnormality then CTG is required to confirm or rule out abnormality anyway. In the UK for low risk labours IA is the recommended method of fetal monitoring. However, there is a new risk that FHR decelerations limited to contractions may be used as an indication to switch over to CTG. These decelerations are common but benign (early). A large number of cases would be unnecessarily switched over to CTG or transferred to hospital obstetric units, with resultant disempowerment of patients and midwifery practice and increased medical intervention. 4 Hitherto they have been rightly disregarded based on sound pathophysiology, longstanding British obstetric and midwifery practice and experience. 4 A stance that it does not matter what label we attach to FHR decelerations is fallacious.
Cerebral Palsy litigation: Rarely, there are major mistakes in CTG interpretation which on balance of probability would account for CP. Barring that, the large scale proliferation of CP litigation and ever increasing legal expenses/claims are largely the fault of the legal system rather than CTG. Moreover, recently there have been many changes and even "U" turns in CTG interpretation guidelines, raising serious doubts about the validity of previous practice, and birth attendants have been left confused. However, this is no fault of the victims of intrapartum hypoxia. Thus for the time being a "no-fault" compensation (at a much lower monetary value) needs consideration. The International Cerebral Palsy Task Force report 5 remains valid in court-rooms but with one clarification. In defining neurological injury from acute intrapartum hypoxia, a sentinel hypoxic event in labour is not essential but rather one of the non-essential criteria.5
"More research is required" may be a benign "truism" but it should not detract us from critically examining the failure of previous 50 years of research and applying analytical methods to the validity of current CTG interpretation.4 The birth-related professional bodies have an imperative to undertake a fundamental re-think in CTG interpretation.
Declaration of interest: The author has no conflict of interest to declare.
Mr Shashikant L Sholapurkar, MD, DNB, MRCOG
Obstetrician and Gynaecologist,
Royal United Hospital Bath NHS Trust, Bath, UK
1. Nelson KB, Sartwelle TP, Rouse DJ. Electronic fetal monitoring, cerebral palsy, and caesarean section: assumptions versus evidence. BMJ 355:i6405. doi: 10.1136/bmj.i6405.
2. Greenhalgh T, Howick J, Maskrey N; Evidence Based Medicine Renaissance Group. Evidence based medicine: a movement in crisis? BMJ 2014; 348:g3725.
3. Sholapurakr SL. Intrapartum fetal monitoring: overview, controversies and pitfalls. The Health foundation, London, UK, 2015. Patient Safety Resource Centre. http://patientsafety.health.org.uk/resources/intrapartum-fetal-monitorin...
4. Sholapurkar SL. Categorization of Fetal Heart Rate Decelerations in American and European Practice: Importance and Imperative of Avoiding Framing and Confirmation Biases. J Clin Med Res 2015; 7: 672-680.
5. MacLennan A. A template for defining a causal relation between acute intrapartum events and cerebral palsy: international consensus statement. BMJ 1999; 319:1054-1059.
Competing interests: No competing interests