CARDIOTOCOGRAPHY
CTG machine has two sensors:
Cardio probe: placed on the mother’s abdomen at the foetal anterior shoulder to measure the foetal heart rate.
Toco probe: placed on the mother’s fundus to record uterine muscle contraction.
(Jelly is to be applied between the probe and the site of application of the probe)
CTG paper moves at rate of 3cm/min
Therefore 1cm = 20 sec on x-axis
Also 1 cm = 10 bpm on Y axis
To be taken every 2 hours towards the end of pregnancy.
When analysing a CTG look for 4 things:
1. Baseline heart rate
2. Beat to Beat variability
3. Accelerations
4. Decelerations
Foetal Heart rate: Normal: 110-160 bpm
Beat to beat variability: Normal: 5-25bpm showing saw tooth pattern
Foetal accelerations:
Abrupt increase in FHR above baseline.
If a rise of 15 bpm persists for 15 sec or more but less than 2 mins is seen twice during a 20 min period then this is adequate contractions or REACTIVE (after 32 weeks).
Foetal decelerations:
Decrease of 15 bpm in FHR for ≥15 seconds
Time from onset of the deceleration to the lowest point of the deceleration >30 seconds in variable decelerations.
Early decelerations: Cause: pressure on the foetal head during labour (normal)
If late or variable decelerations are present, call a senior.
If all 4 parameters normal: REASSURING NST
If any 1 abnormal: SUSPICIOUS NST
If any 2 or more abnormal: PATHOLOGICAL NST
If CTG is non-reassuring:
Set up IV line
Start RL/Oxygen
Give left lateral position
Call the resident
Stop oxytocin
Ask sister to give OT changes/scrubs
Written by our guest author - Yash Bandewar and Anveshi Nayan
Illustration by Devi Bavishi
