CTG Flashcards
What is a CTG?
Cardiotocograph - this measures foetal heart rate in relation to contractions.
How do we assess a CTG?
DR C BRAVADO
Define DR C BRAVADO
DR- Define risks C- contractions BRa- Baseline rate V- variability A- accelerations D-decelerations O-overall
What is the range of baseline rate for a foetus?
110-160 bpm
As the foetus grows and reaches older gestational age, what happens to its BRa?
It decreases, as it usually does in humans
What is an acceptable variability?
5-25 beats
What are accelerations?
Upward deflections in the foetal HR of 15 beats or more than the BRa for more than 15 seconds.
What are decelerations?
Downwards deflections in foetal HR of 15 beats or more than the BRa for more than 15 seconds.
What are the types of decelerations?
Early, late and variable
What is an early deceleration?
A deceleration that occurs during the contraction
What is a late deceleration?
A deceleration that occurs after the contraction
What is variable deceleration?
Decelerations that occur as a mixture of both early and late. This is a rapid fall in BRa with a variable recovery.
What can cause foetal tachycardia?
- Foetal hypoxia
- Chorioamnionitits
- Hyperthyroidism
- Foetal or maternal anaemia
- Foetal tachyarrythmia
What can cause foetal bradycardia?
- Postdate gestation
- OP or OT presentation
What are the characteristics of prolonged severe bradycardia?
Less than 80bpm for more than 3 minutes
What can cause prolonged severe bradycardia?
- Prolonged cord compression
- Cord prolapse
- Epidural/spinals
- Maternal seizure
- Rapid foetal descent
How can variability be categorised?
Reassuring
Non-reassuring
Abnormal
Define reassuring variability
5-25 bpm
Define non-reassuring variability
- Less than 5bpm for 30-50 minutes
- More than 25 bpm for 15-25 minutes
Define abnormal variability
- Less than 5 bpm for more than 50 minutes
- More than 25 bpm for more than 25 minutes
- Sinusoidal
Give 6 reasons for reduced variability in foetal HR
- Foetal sleeping - this is the most common cause but will not last for any more than 40 minutes
- Foetal acidosis - due to hypoxia (more likely if there are also late decelerations)
- Foetal tachycardia
- Drugs - opiates, benzodiazepines, methyldopa and magnesium sulphate
- Prematurity - <28 weeks
- Congenital heart abnormalities
When should accelerations be seen if the foetus is healthy?
At the same time as uterine contractions
What causes an early deceleration?
This is due to increased foetal intracranial pressure and this increases vagal tone. Once the contraction ends and the foetal intracranial pressure returns to normal, the deceleration ends. This means this is a physiological deceleration.
