The Taylor&Emmet Blog

The Interpretation of a CTG Trace

blue_camillaa_panelThe CTG (Cardiotocograph) records the fetal heart rate and uterine contractions and is intended to recognise fetal hypoxia (where the baby is deprived of oxygen).

One electrode is placed on the mother’s abdomen (or on the baby’s scalp inside the womb) and this picks up the baby’s heart rate. A second electrode is also placed on the mother’s abdomen and this records the frequency of her contractions which is the ‘Toco’ part of the CTG graph (see fig 1 below) and the results are printed out onto two graphs side by side.


The problem with the CTG is human interpretation. Historically the CTG trace was read using pattern recognition, which has resulted in significant errors during interpretation. The misinterpretation has resulted in interventions such as forceps, vacuums or emergency caesarean sections being carried out perhaps unnecessarily. The ‘Ten Years of Maternity Claims’ report by the NHS Litigation Authority found that misinterpretation of the CTG is a significant factor in maternity clinical negligence claims. The report highlights that misinterpretation of CTG has sadly contributed to the £1.2 billion pounds paid out by the NHS for cerebral palsy claims during this period. The NHS Litigation Authority found that out of 100 still birth claims, 34 were because the CTG interpretation was read wrong. In 2015 The Royal College of Obstetricians & Gynaecologists produced a report called “Each Baby Counts”. The report is written to ‘peel back the curtain on the true scale of the challenge facing our profession and identifies the scale of the problem’. The aim of Each Baby Counts is to ‘achieve a 50% reduction by 2020 in incidents during term labour that lead to stillbirth, early neonatal death or severe brain injury’.

Mr Edwin Chandraharan, Clinical Director and Obstetrics and Gynaecology and Delivery Suite Lead at St George’s Hospital was quoted in the news in 2011 as saying that ‘while CTGs were hard to read, maternity staff were making too many mistakes. About 500 babies a year die because of this problem, and an unknown number of others suffer brain damage, such as cerebral palsy’. False positives from CTG and the misreading of the printout have an important impact on the way deliveries are handled. A lack of knowledge causes panic and further action to be taken based on incorrect readings.

Problems have also been highlighted with fetal scalp blood sampling (FBS) where a cut is made to the baby’s head before delivery for the blood to be tested so that the results can be analysed alongside the CTG trace. The NHS NICE Guidelines on Intrapartum Care published in December 2014 recommends the use of FBS. This is a controversial procedure as recent evidence has found that the use of FBS does not reduce operative interventions during delivery. Mr Edwin Chandraharan indicates in his commentary published in 2016 on “Should national guidelines continue to recommend fetal scalp blood sampling during labor?” that FBS is used in the UK due to the “personal experience” of a few members of the Clinical Guideline Developing Group (“CDG”) rather than because of any “robust scientific evidence”. The use of FBS has been noted to cause infection and can also cause fluid to drain from around the brain. FBS can cause stress to the baby during the procedure itself, which will in turn effect the CTG results. There have been two Cochrane Systematic Reviews in 2008 and 2013 and both concluded that there was no evidence that fetal blood sampling was useful, or that it ‘reduce[d] caesarean sections or instrumental vaginal births’. Mr Chandraharan considers that ‘in the era of evidence-based medicine’ it is not acceptable to allow FBS to continue as the evidence shows that FBS actually increases the caesarean section rate and instrumental delivery rate. The NHS Hospital Trusts are divided on the topic because the NICE Guidelines still have FBS within their recommendations and state that “FBS would reduce more serious interventions”.

Mr Chandraharan and many labour ward leads across maternity units in London for example do not agree with the Guidelines. St George’s Maternity Unit in London for example do not use FBS at all. St George’s have adopted a system of increased CTG training among staff including mandatory testing as well as an approach that interprets the CTG alongside the physiology of mother and baby and during labour. They have seen excellent results with their emergency caesarean section numbers halving over the last 5 years and they are now the lowest in London at 6-8% of deliveries. They have also seen a dramatic decrease in the rate of hypoxic injury which is half the nationally reported rate.

A total of £198.8 million was paid out by the NHS Litigation Authority who act for the hospital trusts in clinical negligence claims. They settled 130 cerebral palsy clinical negligence cases between 2006-2010. In 78 of those cases the babies tragically died. In 43 cases the baby developed cerebral palsy because they were deprived of oxygen. In both these figures these cases were noted by the NHS Litigation Authority as being as a result of the misreading of a CTG.

If you have any concerns regarding fetal scalp blood sampling or a brain or birth injury caused by delay or problems that occurred during labour please contact us to discuss your concerns. Alternatively if you would prefer to email your concerns to us and find out more please contact us at

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