Foetal distress in labour (incl. fetal blood sampling)

Question 1

Define foetal distress.

Answer 1

defined as hypoxia that might result in fetal damage or death if not reversed or the fetus delivered urgently

hypoxia is the best known cause of intrapartum fetal damage and scalp blood pH of <7.20 indicates significant hypoxia (although in reality this is not uncommon in labour and most babies will have no sequelae at this pH). Risk increases at pH <7.00 where neurological damage is then more common.

Question 2

What is the aetiology of fetal distress?

Answer 2

Contractions may temporarily reduce placental perfusion and may compress the umbilical cord so longer labours or if >1hr spent pushing

Question 3

What are the risk factors for fetal distress?

Answer 3

Intrapartum:

• long labour
• meconium
• epidural use
• oxytocin use

Antepartum:

• PET
• IUGR

Usually monitored with CTG in labour if any of these RFs present

Question 4

How do you diagnose fetal distress?

Answer 4

• Fetal acisosis (scalp pH <7.20)
• Ominous FHR abnormalities

Question 5

List 3 different methods of monitoring for fetal distress.

Answer 5

Colour of liquor - meconium staining - uncommon if preterm but common after 4 weeks. Undiluted meconium may be significant and CTG should be done. Fetus may aspirate it and hypoxia is more likely.

FHR auscultation

CTG - from a transducer placed on the abdomen or probe in the vagina attached to the fetal scalp

Fetal ECG monitoring - some evidence shows that with CTG it can improve neonatal outcomes

Fetal blood (scalp) sampling (FBS)

Question 6

What is this?

Answer 6

Pinard’s stethoscope

Question 7

What is this?

Answer 7

Fetal scalp electrode for fetal monitoring in labour

Question 8

How often is FHR monitored in labour? How long for?

Answer 8

• First stage - every 15 minutes
• Second stage - every 5 minutes

…with a Pinard’s stethoscope or a hand-held Doppler for 60 seconds after a contraction.

Question 9

How is FBS carried out? What can be measured from this?

Answer 9

• Amnioscope inserted vaginally through the cervix
• Scalp cleaned
• Small cut made where blood is collected into microtube
• pH and lactate can be immediately analysed

Question 10

What does this show?

Answer 10

Acute fetal distress; the fetus is dying

Question 11

What does this show?

Answer 11

Normal cardiotocography (CTG); acceleration of the fetal heart with contractions.

Question 12

What does this show?

Answer 12

Early decelerations are synchronous with a contraction.

Question 13

What does this show?

Answer 13

decelerations, tachycardia, reduced variability suggestive of fetal distress.

Question 14

What is the management of fetal distress?

Answer 14

Depending on situation:

In utero resuscitation -

• place mother in left lateral position to avoid aortocaval compression
• oxygen and IV fluids
• stop oxytocin infusion
• terbutaline (tocolytic) - beta-2-agonist to stop contractions
• vaginal exam - exclude cord prolapse or very rapid progress

If these fail then FBS is done

• If pH <7.20 then expedite delivery
• If >7.20 but abnormal FHR on CTG continues/deteriorates then another sample at 30min
• If impossible to take sample: exoedite delivery

Question 15

How can you reduce meconium aspiration intra partum?

Answer 15

Where the meconium is thick, amniofusion of saline into the uterus to dilute the meconium reduces the incidence of meconium aspiration

Question 16

What is the significance of any maternal fever?

Answer 16

Even low-grade fever is a strong risk factor for seizures, fetal death and cerebral palsy even in absence of evidence of infection.

Unknown whether this is due to the causes of the fever or the fever itself i.e. overheating so optimum medical treatment is unknown.

Question 17

Name a cause of fetal blood loss which may cause fetal distress,

Answer 17

Very rare but is due to vasa praevia feto-maternal haemorrhage or, on occasion, placental abruption.