Intrapartum fetal scalp lactate sampling for fetal assessment in the presence of a non-reassuring fetal heart rate trace
Editorial Group: Cochrane Pregnancy and Childbirth Group
Published Online: 17 MAR 2010
Assessed as up-to-date: 17 FEB 2010
Copyright © 2012 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
How to Cite
East CE, Leader LR, Sheehan P, Henshall NE, Colditz PB. Intrapartum fetal scalp lactate sampling for fetal assessment in the presence of a non-reassuring fetal heart rate trace. Cochrane Database of Systematic Reviews 2010, Issue 3. Art. No.: CD006174. DOI: 10.1002/14651858.CD006174.pub2.
- Publication Status: Edited (no change to conclusions)
- Published Online: 17 MAR 2010
Fetal blood sampling for lactate estimation may be considered following identification of an abnormal or non-reassuring fetal heart rate pattern. The smaller volume of blood required for this test, compared with the more traditional pH estimation, may improve sampling rates. The appropriate use of this practice mandates systematic review of its safety and clinical effectiveness prior to widespread introduction.
To evaluate the effectiveness and risks of fetal scalp lactate sampling in the assessment of fetal well-being during labour, compared with no testing or alternative testing.
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2009).
All published and unpublished randomised and quasi-randomised trials that compared fetal scalp lactate testing with no testing or alternative testing to evaluate fetal status in the presence of a non-reassuring cardiotocograph during labour.
Data collection and analysis
Two review authors assessed the studies independently.
The two identified randomised trials considered outcomes for 3348 mother-baby pairs allocated to either lactate or pH estimation of fetal blood samples in labour. There were no statistically significant differences for any fetal/neonatal/infant outcomes, including low Apgar score at five minutes, admission to neonatal intensive care units or neonatal encephalopathy, or for low umbilical arterial pH, base deficit or metabolic acidaemia. There was a statistically higher success rate for lactate compared with pH estimation (risk ratio 1.10, 95% confidence interval 1.08 to 1.12, n = 2992). There were no significant between-group differences in mode of birth or operative birth for non-reassuring fetal status. No studies reported outcomes of maternal satisfaction with fetal monitoring, anxiety, length of hospital stay or economic analysis.
When further testing to assess fetal well-being in labour is indicated, fetal scalp blood lactate estimation is more likely to be successfully undertaken than pH estimation. Action cut-off lactate values need to consider the lactate meter used. Further studies may consider sub-group analysis by gestational age, the stage of labour and sampling within a prolonged second stage of labour. Additionally, future studies may address longer-term neonatal outcomes, maternal satisfaction with intrapartum fetal monitoring and an economic analysis.
Plain language summary
Use of fetal scalp blood lactate for assessing fetal well-being during labour
A fetal heart rate that is abnormal or not reassuring during labour may be caused by the inability of the baby to adapt to decreases in oxygen supply during the birth. Inadequate oxygen supply may lead to the development of acidosis (low pH levels) and increased lactate in the blood. After the amniotic membranes have ruptured and the cervix dilated to around 3 cm, it is possible to measure lactate (or pH) levels in a sample of blood taken from the baby's scalp. A much smaller amount of blood is needed for the lactate test than to measure pH. This review identified two studies of 3348 mother-baby pairs that compared lactate and pH testing in labour. Lactate testing was more likely to be successful than pH testing, but with no differences in newborn outcomes, including the number of babies with low Apgar scores, low pH in their cord blood or admissions to the neonatal intensive care nursery. There were no differences in the number of mothers having caesarean sections, forceps or vacuum births between the two groups. We conclude that lactate testing in labour may be more likely to be successfully achieved than pH testing.