An admission CTG is a short (typically 20 – 30 minute) period of CTG monitoring performed when a woman first presents to a maternity service in labour. The assumption on which the use of admission CTGs is based is that this screening test, offered to women considered to be at low risk (and therefore considered not eligible for intrapartum continuous CTG monitoring) can detect a cohort of fetuses who are at increased risk. Intrapartum CTG monitoring is then advised, in the belief that this will reduce the risk of poor perinatal outcome.
The logic behind this approach is flawed
For admission CTG monitoring to be effective in reducing perinatal mortality or long-term neurological injury for the fetus, intrapartum CTG monitoring must also be effective in perinatal mortality or long-term neurological injury for the fetus. In the face of evidence that intrapartum CTG monitoring is ineffective, there is then no logical way in which admission CTG monitoring could possibly be effective. That research was ever conducted to examine the effectiveness of admission CTG monitoring is an illustration of the remarkable triumph of optimism that CTG monitoring might work over the reality of what was already known.
By 2001, ten RCTs regarding intrapartum CTGs had been published and three systematic literature reviews had been reported, each showing that intrapartum CTG monitoring did not reduce perinatal mortality. The first RCT examining the use of admission CTGs was published in 2001 (Mires et al., 2001) with three others being added in the next seven years (Cheyne et al., 2003; Impey et al., 2003; Mitchell, 2008) and then another in 2018 (Smith et al., 2018). It would have been reasonable to assume that admission CTGs were not going to be effective on the basis that intrapartum CTGs were not shown to be effective. Let’s look at what the research found.
Devane et al. (2017) analysed the four trials published between 2001 and 2008 in their 2017 Cochrane review, which included a total of 11,338 women. The use of admission CTGs for low risk women, rather than intermittent auscultation, was associated with:
- A 20% increase in caesarean section
- A 30% increase in the use of intrapartum CTG monitoring (which is to be expected given the purpose of admission CTGs)
- A 28% increase in the use of fetal blood sampling
- No difference in the perinatal mortality rate
- No difference in the incidence of low Apgar scores, hypoxic ischaemic encephalopathy, neonatal seizures, or admission to the neonatal nursery
- No change in the use of amniotomy, augmentation with oxytocin, or epidurals
They noted that none of the research assessed for long term neurological outcomes.
Smith and co-authors added further evidence in 2018 comparing admission CTGs with IA in low risk women, with 3,034 women in their randomised controlled trial conducted in Dublin. They found:
- A similar sized increase in the caesarean section rate (24%), however this failed to reach statistical significance (95% confidence intervals 0.97 – 1.59)
- An increase in the use of intrapartum CTG monitoring
- No difference in the perinatal mortality rate (with no deaths in either group)
- No difference in the use of amniotomy, oxytocin augmentation or epidurals
- No difference in the incidence of low Apgar scores, cord blood acidosis, the use of neonatal resuscitation, or admission to the neonatal nursery
Again, the research was not designed to examine longer term perinatal outcomes.
No benefit for the baby, increased risk for women
Evidence regarding the use of admission CTGs therefore fails to demonstrate benefits for the baby. Women face increased risks in the form of caesarean section. By definition these additional caesarean sections would be unnecessary as they did not benefit the baby. This should not come as a surprise, given what we knew about intrapartum CTG monitoring before the first randomised controlled trial of admission CTGs was conducted.
There is no justification for the use of admission CTGs
De-implementing intrapartum CTG monitoring is a monumental challenge. Removing the use of admission CTGs is far easier to achieve. At the time that a woman first attends a maternity service during labour a comprehensive assessment of her wellbeing and that of her fetus(es) is appropriate. There are multiple ways to assess fetal wellbeing. A structured and physiologically informed approach to auscultating the fetal heart is one part of such an assessment. The use of admission CTGs can not be justified, and will not be able to be justified while there is evidence that intrapartum CTG monitoring does not improve perinatal outcome.
Cheyne, H., Dunlop, A., Shields, N., & Mathers, A. M. (2003). A randomised controlled trial of admission electronic fetal monitoring in normal labour. Midwifery, 19(3), 221-229.
Devane, D., Lalor, J. G., Daly, S., McGuire, W., Cuthbert, A., & Smith, V. (2017). Cardiotocography versus intermittent auscultation of fetal heart on admission to labour ward for assessment of fetal wellbeing. Cochrane Database of Systematic Reviews, 1, CD005122. https://doi.org/10.1002/14651858.CD005122.pub5.
Impey, L., Reynolds, M., MacQuillan, K., Gates, S., Murphy, J., & Sheil, O. (2003). Admission cardiotocography: a randomised controlled trial. Lancet, 361(9356), 465-470. https://doi.org/10.1016/S0140-6736(03)12464-6
Mires, G. J., Williams, F., & Howie, P. (2001). Randomised controlled trial of cardiotocography versus Doppler auscultation of fetal heart at admission in labour in low risk obstetric population. British Medical Journal, 322(7300), 1457-1460.
Mitchell, K. (2008). Effect of a labour electronic fetal monitoring admission test on operative delivery in low-risk women: a randomised controlled trial. Evidence Based Midwifery, 6(1), 18-26.
Smith, V., Begley, C. M., Newell, J., Higgins, S., Murphy, D. J., White, M. J., Morrison, J. J., Canny, S., O’Donovan, D., & Devane, D. (2018, Aug 20). Admission cardiotocography versus intermittent auscultation of the fetal heart in low-risk pregnancy during evaluation for possible labour admission – a multicentre randomised trial: The ADCAR trial. British Journal of Obstetrics and Gynaecology, 126(1), 114-121. https://doi.org/10.1111/1471-0528.15448
Tags: Admission CTG