Assessment of Foetal Wellbeing

Question 1

Describe the general methods of assessing foetal wellbeing

Answer 1

• Movements
• Fundal height
• Biochemical parameters
• Ultrasound
• CTG

Question 2

Describe the ultrasound parameters used to determine foetal wellbeing

Answer 2

• Biometry (head/abdo circumference, femur length)
  
  • Abdominal circumference most important
• Liquor volume (amniotic fluid index - normally 7-24)
• Doppler (umbilical, MCA)
  
  • Umbilical artery waveform - gives systolic/diastolic ratio (SDR)
• Activity (body - fine and gross movements, breathing, tone) - only done if other parameters abnormal when delivery is not an option (i.e. 23-30 weeks)

Question 3

What are the components assessed on a CTG?

Answer 3

• Baseline
• Variability
• Accelerations/decelerations
• Uterine contractions

Question 4

What is the normal CTG baseline range?

Answer 4

110-160 bpm

Question 5

What is the normal variability range on a CTG?

Why might it decrease? Increase? Be sinusoidal?

Answer 5

• 5-25 bpm
• Reduction - SSSS - (Sleeping, Sick (severe hypoxia), Sedated (meds), Submature (prem))
• Increase - hypoxia
• Sinusoidal - foetal anaemia

Question 6

What is the normal number of accelerations present in a CTG?

Answer 6

2 accelerations of 15bpm in 20 minutes

Question 7

Why might you see early decelerations on a CTG? What are they?

Answer 7

• Generally in S2 of labour simultaneously with contractions as the head is squashed. Due to activation of a pain receptor. Fairly rare. Not ominous

Question 8

Why might you see late decelerations on a CTG? What are they?

Answer 8

• Ominous (foetal hypoxia). Peaks after contraction peak. Due to activation of chemoreceptors

Question 9

When might you see variable decelerations on a CTG? What are they? When would you call them severe?

Answer 9

• Ominous (cord compression). Rapid onset and recovery, differing size/shape, simultaneous with contraction. Due to baroreceptor activation. Common in late labour
• Severe - >60bpm AND >60sec OR delayed recovery OR rebound tachycardia

Question 10

When might you see prolonged decelerations on a CTG? What are they?

Answer 10

• Ominous (sustained hypoxia). More than 2 mins duration of bradycardia. Due to chemoreceptor activation
  
  • Cord compression, maternal hypotension, sustained uterine contraction, placental abruption
• Delivery imminently required