foetal blood sampling

Question 1

when is FBS indicated

The procedure involves making a small incision of the foetal scalp transvaginally. The blood is then collected and analysed for acidaemia.

Answer 1

Foetal blood sampling (FBS) is indicated when there is a suspicious cardiotocograph. It is used during labour to confirm whether there is foetal hypoxia.

Question 2

when can you not do FBS

Answer 2

Contraindications for FBS
Prolonged decelerations on cardiotocography
Maternal infection e.g. HIV, herpes simplex
Prematurity (<34 weeks)

Question 3

what do you interpret

Answer 3

Interpretation of FBS
Use either pH or lactate when interpreting foetal blood sample results.

Use the following classifications for foetal blood sample results:

pH:

normal: 7.25 or above
borderline: 7.21 to 7.24
abnormal: 7.20 or below
OR

Lactate:

Normal: 4.1 mmol/l or below
Borderline: 4.2 to 4.8 mmol/l
Abnormal: 4.9 mmol/l or above

Question 4

If the foetal blood sample result is abnormal:

Answer 4

Inform a senior obstetrician and the neonatal team
Talk to the woman and her birth companion(s) about what is happening and take her preferences into account and
Expedite the birth - c section

If the foetal blood sample result is borderline and there are no accelerations in response to foetal scalp stimulation, consider taking a second foetal blood sample no more than 30 minutes later.

If the foetal blood sample result is normal and there are no accelerations in response to foetal scalp stimulation, consider taking a second foetal blood sample no more than 1 hour later.