CTG

Question 1

What’s the normal foetal heart rate?

Answer 1

110-160 beats/min

Question 2

What’s the normal baseline foetal heart rate?

Answer 2

Mean foetal heart rate over 5-10 min

Question 3

Causes of sustained foetal tachycardia on CTG? (5)

Answer 3

• prematurity → (rate slows down with advancing gestational age)
• hypoxia
• foetal distress
• maternal pyrexia
• use of beta-agonist (e.g. Salbutamol)

Question 5

What are the causes of baseline foetal bradycardia?

Answer 5

Severe foetal distress, due to:

• placental abruption
• uterine rupture

More commonly occurs with:

• hypotension
• maternal sedation
• postmaturity
• hypoxia

Question 6

What does a sustained foetal heart rate baseline under 90 beats/min mean?

Answer 6

Impending foetal death → need to act on it without a delay !!!

Question 7

What does baseline variability mean?

Answer 7

Fluctuations in the fetal HR from one beat to the next

Question 8

How is the baseline variability calculated?

Answer 8

Measuring the distance between the highest peak and the lowest through 1- a minute segment of CTG trace

Question 9

What is the value of normal baseline variability?

Answer 9

Between 5 - 25 beats/ min

• it’s a good indicator of foetal well-being

Question 10

When can reduced variability be seen? (3)

Answer 10

• foetus is asleep → safely lasts up to 40 mins
• seen in early gestation
• drugs: opiates or benzodiazepines

*prolonged reduced variability = severe foetal distress

Question 11

What are accelerations?

How many of them do we expect?

Answer 11

• raise in a foetal HR at least 15 beats/min for at least 15 seconds

We should expect at least 2 accelerations every 15 minutes

Question 12

Are accelerations good sign?

Answer 12

• accelerations are reassuring
• often seen with contractions

*although there are common to be absent in advanced labour

Question 13

What are decelerations?

Answer 13

Fall in a foetal HR at least 15 beats/min for more than 15 seconds

Question 14

What are early decelerations?

What shape they are?

Answer 14

deceleration = fall in foetal HR of at least 15 beats/min for more than 15 seconds

Early decelerations: occur with contraction and return to normal by the end of contraction

(physiological/normal response)

• shape: uniform in depth, length and shape

Question 15

When late decelerations occur?

Answer 15

deceleration = fall in foetal HR of at least 15 beats/min for more than 15 seconds

• occur during the contraction and return to baseline AFTER the contraction
• suggestive of foetal distress
• they are more worrying if they are shallow and late

Question 16

What are the variable decelerations?

What do they suggest?

Answer 16

deceleration = fall in foetal HR of at least 15 beats/min for more than 15 seconds

• vary in timing and shape in relation to uterine contraction

Suggestive of: cord compression (especially in oligohydramnios)

Question 17

What does ‘Shouldering’ sign mean?

Answer 17

• there is small acceleration before and after the deceleration
• meaning: foetus is coping well with the compression

Question 18

What does sinusoidal trace mean?

Answer 18

• smooth, wavy sine-wave-like baseline with no variability
• the pattern last over 10 min
• amplitude 5-15 beats/min

Question 19

Causes of sinusoidal trace

Answer 19

• smooth, wavy sine-wave-like baseline with no variability
• the pattern last over 10 min
• amplitude 5-15 beats/min

Causes: physiological or foetal anaemia, hypoxia

• must be considered SERIOUS until proven otherwise

Question 20

What’s pseudo sinusoidal trace?

Answer 20

• benign
• uniform
• long-term pattern
• less regular in shape and amplitude when compared to sinusoidal trace

Sinusoidal trace:

• smooth, wavy sine-wave-like baseline with no variability
• the pattern last over 10 min
• amplitude 5-15 beats/min