9.4 Cardiotocography

Question 1

What is CTG used to measure?

Answer 1

• fetal heart rate

- uterine contractions

Question 2

How do the two transducers measure in CTG?

Answer 2

• one above fetal heart uses doppler

- one near the fundus uses US to assess tension of uterine wall (demonstrating contractions)

Question 3

What are 8 indications for continuous CTG?

Answer 3

• sepsis
• maternal tachycardia (>120)
• significant meconium
• pre-eclampsia es >160/110
• fresh antepartum haemorrhage
• delay in labour
• use of oxytocin
• disproportionate maternal pain

Question 4

What are the 5 key features of a CTG?

Answer 4

• contractions (no in 10 mins)
• baseline rate (fetal HR)
• variability (around baseline)
• accelerations (spikes in fetal HR)
• decelerations (drops in fetal HR)

Question 5

What is a reassuring baseline rate and variability?

Answer 5

110-160

5-25

Question 6

What is a non-reassuring baseline rate and variability?

Answer 6

100-109 or 161-180

less than 5 for 30-50 mins
or
more than 25 for 15-25 mins

Question 7

What is an abnormal baseline rate and variability?

Answer 7

below 100 or above 180

less than 5 for over 50 mins
or
more than 25 for over 25 mins

Question 8

What are the 4 types of decelerations?

Answer 8

• early decelerations
• late decelerations
• variable decelerations
• prolonged decelerations

Question 9

What are the features and cause of early decelerations?

Answer 9

• dip and recovery in HR that corresponds with contraction
• lowest point is peak of contraction
• normal
• caused by head compression stimulating the vagus nerves –>HR slows.

Question 10

What are the features and cause of late decelerations?

Answer 10

• fall in HR starting after a contraction has begun
• lowest point is after peak of contraction
• concerning finding –> hypoxia in fetus
• could be due to excessive uterine contractions, maternal hypotension / hypoxia.

Question 11

What are the features and cause of variable decelerations?

Answer 11

• abrupt decelerations unrelated to contractions
• fall of more than 15 from baseline
• low point within 30 secs and normal within 2 mins
• intermittent compression of umbilical cord
• “shoulders” are accelerations either side –> show fetus is coping
• less than 90 mins of it is fine

Question 12

What are the features and cause of prolonged decelerations?

Answer 12

• decelerations lasting between 2 and 10 mins
• drop of more than 15 from baseline
• indicates cord compression causing fetal hypoxia
• abnormal and concerning

Question 13

What are the criteria for the 4 categories of CTG?

Answer 13

• normal = normal
• suspicious = 1 non-reassuring feature
• pathological - two non reassuring features
• need urgent intervention = acute bradycardia or prolonged deceleration >3mins

Question 14

What is the “rule of 3s” for fetal bradycardia?

Answer 14

3mins - call for help
6 mins - move to theatre
9 mins - prepare for delivery
12mins - deliver baby

(pH can drop at 0.01 every 2-3 mins)

Question 15

What is an acceptable fetal pH?

Answer 15

> 7.20

Question 16

What are the features and cause of sinusoidal CTG?

Answer 16

rare pattern
sine wave with smooth amplitude of 5-15

• associated with fetal anaemia eg vasa previa with fetal haemorrhage.

Question 17

Is the mnemonic to assess a CTG in a structured way?

Answer 17

DR C BRaVADO

Question 18

What are the steps in DR C BRaVADO?

Answer 18

DR - Define Risk (Hx and pregnancy)

C - Contractions

BRa - Baseline Rate
V - Variability
A - Accelerations
D -  Decelerations 
O - Overall impression (normal, suspicious, pathological, need urgent intervention)