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Flashcards in CTG Deck (20)
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1

What's the normal foetal heart rate?

110-160 beats/min

2

What's the normal baseline foetal heart rate?

Mean foetal heart rate over 5-10 min

3

Causes of sustained foetal tachycardia on CTG? (5)

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

4

5

What are the causes of baseline foetal bradycardia?

Severe foetal distress, due to: 

  • placental abruption
  • uterine rupture

More commonly occurs with: 

  • hypotension
  • maternal sedation
  • postmaturity
  • hypoxia

6

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

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

7

What does baseline variability mean?

Fluctuations in the fetal HR from one beat to the next

 

 

8

How is the baseline variability calculated?

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

9

What is the value of normal baseline variability?

Between 5 - 25 beats/ min 

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

10

When can reduced variability be seen? (3)

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

 

*prolonged reduced variability = severe foetal distress 

11

What are accelerations?

 

How many of them do we expect?

  • 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

12

Are accelerations good sign?

  • accelerations are reassuring 
  • often seen with contractions 

 

*although there are common to be absent in advanced labour

13

What are decelerations

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

14

What are early decelerations?

What shape they are?

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

 

15

When late decelerations occur?

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

16

What are the variable decelerations?

What do they suggest?

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) 

 

17

What does 'Shouldering' sign mean?

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

18

What does sinusoidal trace mean?

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

19

Causes of sinusoidal trace

  • 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 

20

What's pseudo sinusoidal trace?

  • 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