Cardiotocography Flashcards
What is CTG used for?
Monitoring foetal heart rate and contraction of the uterus
How is a CTG taken
2 transducers are placed on the abdomen, one over the foetal heart to measure foetal heartbeat and one over the fundus to measure contractions
Indications for continuous CTG monitoring
- Sepsis
- Maternal tachycardia (> 120)
- Significant meconium
- Pre-eclampsia (particularly blood pressure > 160 / 110)
- Fresh antepartum haemorrhage
- Delay in labour
- Use of oxytocin
- Disproportionate maternal pain
What are the 5 key features of CTG
- Contractions– the number of uterine contractions per 10 minutes
- Baseline rate– the baseline fetal heart rate
- Variability– how the fetal heart rate varies up and down around the baseline
- Accelerations– periods where the fetal heart rate spikes
- Decelerations– periods where the fetal heart rate drops
What does contractions show on CTG
Evidence of failure to progress or uterine hyperstimulation
What do accelerations show on CTG
A healthy foetus (Especially when alongside contractions)
Normal baseline foetal heart rate on CTG
110-160
Non-reassuring baseline foetal heart rate on CTG
100-109 or 161-180
Abnormal baseline foetal heart rare on CTG
<100 or >180
Normal variability on CTG
525
Non reassuring variability on CTG
<5 for 30-50 minutes
>25 for 15-25 minutes
Abnormal variability on CTG
<5 for >50 minutes
>25 for >25 minutes
What are the 4 types of deceleration on CTG
Early
Late
Variable
Prolonged
What are early decelerations on CTG
Gradual dips in heart rate that correspond exactly with uterine contractions
What causes early deceleration on CTG
Uterine contractions compressing the head, stimulating the vagus nerve
What are late decelerations
Gradual falls in heart rate that start after the uterine contraction has begun
What causes late decelerations on CTG
Hypoxia of the foetus due to:
- Excessive uterine contractions
- Maternal hypotension
- Maternal hypoxia
What are variable decelerations?
Falls of 15bpm or more from baseline that are unrelated to uterine contractions, with the lowest point occurring within 30 seconds and lasting less than 2 minutes total
What causes variable decelerations on CTG
Intermitent compression of the umbilical cord causing foetal hypoxia
What is a reassuring sign in variable decelerations on CTG
“Shoulders” - Brief accelerations before and after
What are prolonged decelerations?
Decelerations lasting 2-10 minutes with a drop of 15bpm from baseline
What are the 4 categories for CTG
Normal
Suspicious - 1 non-reassuring feature
Pathological - 1 abnormal or 2 non-reassuring
Needs urgent intervention - Acute bradycardia or prolonged deceleration of >3 minutes
What are some managements of abnormal CTG
Escalate to senior
Further assessment
Conservative interventions (E.g. fluids, repositioning)
Foetal scalp stimulation
Foetal scalp blood sampling for acidosis
Delivery
What is the rule of 3s timeline for foetal bradycardia
- 3 minutes – call for help
- 6 minutes – move to theatre
- 9 minutes – prepare for delivery
- 12 minutes – deliver the baby (by 15 minutes)
Management of foetal bradycardia
Rule of 3 timeline (Delivery in 15 minutes)
What is a sinusoidal CTG
It gives a pattern similar to asine wave, with smooth regular waves up and down that have an amplitude of 5 – 15 bpm
Causes of sinusoidal CTG
Severe fetal anaemia, for example, caused by vasa praevia with fetal haemorrhage.
How should CTG reporting be remembered
DR C BRaVADO
What is DR C BRaVADO
DR - Define Risk
C - Contractions
BRa - Baseline Rate
V - Variability
A - Accelerations
D - Decelerations
O - Overall impression
