QuestionSBA
QuestionChoice
This is a concerning blood sample indicating that the foetus is acidotic, implying hypoxia and therefore needs urgent delivery
32608
a
Urgent delivery
QuestionChoice
Asking the mother to lie in the left lateral position can shift weight off the maternal vessels and correct cord compression, however as the foetal blood sampling is abnormal, the foetus needs to be delivered. Therefore, this is not the right answer
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Ask the mother to lie in the left lateral position
QuestionChoice
This is an abnormal and very worrying result, and therefore time is of the essence. NICE guidance suggests that if pH < 7.20 or lactate is >4.9mmol/L, the foetus should be delivered immediately. If the pH were 7.21 - 7.24 or lactate were 4.2 -4.8mmol/L, it would be reasonable to retest in the first instance
32609
b
Repeat the test in 30 minutes
QuestionChoice
This is an abnormal and very worrying result, and therefore, time is of the essence, and the baby needs to be delivered urgently. Whilst it is important to stay calm and keep the mother reassured, it is important not to give false reassurance at the gravity of the situation
32610
c
Reassure the mother that everything is normal
QuestionChoice
The cardiotocograph will give you an accurate assessment of foetal heart rate (and, in this case, is showing abnormal decelerations). Auscultation would unlikely add anything in this scenario
32611
d
Auscultate for foetal heart rate
QuestionComment
Notes below say prolonged deceleration is a contraindication to FBS. So why was it done?
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Yersinia Jaundice
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CAT1 C-Section 

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Syndrome Bradykinin
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# Summary


Foetal blood sampling (FBS) is a procedure used during labour to confirm whether foetal hypoxia is present in the cases of a suspicious cardiotocograph. The procedure involves a small transvaginal incision in the foetal scalp to collect blood for analysis of acidaemia. It is contraindicated in certain situations such as prolonged decelerations on cardiotocography, maternal infections, and prematurity. The interpretation of FBS results involves either pH or lactate measurements, with results guiding further management which may involve informing a senior obstetrician and the neonatal team, discussing the situation with the woman and her birth companion(s), and potentially expediting the birth.

# Definition


Foetal blood sampling (FBS) is a technique used during labour to assess the presence or absence of foetal hypoxia. 

The need for FBS arises from situations where foetal hypoxia is suspected, often indicated by abnormal foetal heart rate patterns on cardiotocography.


# Signs and Symptoms


Clinical scenarios that may prompt the use of FBS include:

- Suspicious cardiotocograph
- Lack of progress in labour
- Abnormal pH or lactate measurements in previous samples


# Differential Diagnosis


The main differential diagnoses for the findings that prompt FBS include:

- Normal labour variation: Characterised by occasional decelerations in the foetal heart rate with good recovery and no other signs of foetal distress.
- Foetal distress: Characterised by persistent decelerations in the foetal heart rate, poor variability, or late decelerations.
- Maternal hypotension: Characterised by sudden prolonged decelerations in the foetal heart rate, often with a rapid recovery once the mother's blood pressure is corrected.

# 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

Interpret foetal blood sample results taking into account:

- Any previous pH or lactate measurement
- Clinical features of the woman and baby, such as rate of progress in labour and cardiotocography

If the foetal blood sample result is abnormal:

- 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

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.

# References

[NICE guidelines](https://www.nice.org.uk/guidance/cg190/chapter/recommendations#fetal-blood-sampling)



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Interpretation of foetal blood sampling
Topic
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Obstetrics
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Prolonged fetal heart rate decelerations accompanied by acidosis suggest fetal hypoxia, requiring immediate delivery to avoid potential complications.
A 37-year-old primigravida is established in the first stage of labour, and you notice some prolonged decelerations on the cardiotocograph. Foetal blood sampling is performed, and the results are as follows:


||||
|--------------|:-------:|------------------|
|pH|7.14|7.35 - 7.45|
|Lactate|5.3 mmol/L|0.6 - 1.4|



What should you do?
a