If CTG monitoring shows that your baby may not be coping well with labour, you may be offered foetal blood sampling to help guide next moves.
Midwives and obstetricians observing CTG monitoring may notice that your baby’s heart rate is dipping (‘decelerations’) or steadily rising (‘rising baseline’). These can be signs that your baby is not coping well with labour. However, foetal heart monitoring is not an exact science, and these signs can be present but baby may be ok, or they may indicate that your baby needs to be born quickly. Foetal blood sampling gives a bit more information on how your baby is doing, and may be offered to guide decision making.
For foetal blood sampling, you need to be close to or fully dilated, so that the obstetric doctor who will carry out the sampling is able to get to baby’s scalp. If you are in early labour or early established labour and not well dilated yet, but your baby is showing concerning signs on CTG, the team caring for you may recommend a caesarean as they cannot gather any information beyond what baby’s heart rate is doing.
For a foetal blood sample, your feet will be put in stirrups so that the doctor can insert a cone into your vagina that gives a view of baby’s head. They then use a special tool to make a cut on baby’s scalp and take a small sample of blood in a thin glass tube. This sample is then placed in a small machine which will test the lactate levels in that blood sample.
If the lactate levels are high, then the team will discuss with you options for birthing your baby quickly – if your baby is high in your pelvis, then they will likely offer a caesarean birth, but if baby is low in your pelvis then they may be able to offer an assisted vaginal birth or instrumental birth. However, if lactate levels are low then the team may recommend continuing to labour with watchful waiting.
Foetal blood sampling may be repeated if you continue to labour but your baby’s heart tracing still shows signs that it may not be coping well with labour.