CARDIOTOCOGRAPHY (CTG): Vital for Fetal Heart Monitoring

It was a busy night shift in labour ward, the sounds of LUB! DUB! LUB! DUB! of fetal heart rate recordings by CTG machines were coming from different beds, when suddenly a patient came in emergency with 37 week pregnancy, reduced baby movements and abdominal pain. CTG showed severe fetal distress with slow irregular fetal heart rate of 90 beats per minute, immediately she  was shifted to operation theatre for emergency Caesarean Section; where placental bleed and cord around the neck of baby were found. Lives of both mother and baby were saved. Could it be possible without fetal heart monitoring? the answer is a big… NO! 

These modern techniques of monitoring of fetal heart ensure a normal blood supply to the baby and help in markedly reducing fetal deaths and still births. This blog will give basic information of fetal heart rate monitoring during pregnancy and labour, and provide answers to common queries about the various fetal heart rate patterns:

Why monitoring of fetal heart rate is important during labour?
Fetal heart rate tells us about the blood supply to the baby and is an indicator of fetal well being, monitoring during labour anticipates the problems to baby during birth.

How fetal heart rate is monitored?
The old, simple and time tested method of intermittent auscultation by fetoscope or stethoscope and the modern CTG (cardiotocography) machines are used for fetal heart rate monitoring.

What is intermittent auscultation?
If there are no risk factors then a pinard stethoscope or hand held doppler are used for listening to heart beat of baby.

How frequent intermittent auscultation is done during labour?
In first stage of labour heart rate of baby is checked every 15 minutes, whereas it is checked every 5 minutes in second stage of labour.

What are the risks of intermittent auscultation? 
It can miss the sudden, rare but life threatening changes of fetal heart as there is no graphical record of fetal heart rate patterns.

What is CTG (Cardiotocography)?
It’s a graphical representation of baby heart rate and uterine contractions on a paper, just like ECG of heart.

Why CTG is so important?
Normally baby can cope with stress of labour but in some high risk cases some babies go into distress during labour, CTG helps to pick these problems timely, for an appropriate action.

How does CTG machine work?
These are special ultrasound doppler waves which can detect and pick baby heart rate pattern.

How CTG is done?
There is a belt with two flat plastic plates, tied around the tummy to detect uterine contractions and baby heart rate, which is recorded on a CTG paper.

What is a normal CTG ?
The normal heart rate of baby is 110 to 160 beats per minutes, with a variation of 15 to 20 beats per minute. The base line is 130 to 140 beats per minutes. There could be 1 to 2 accelerations (not more than 160 beats per minute) and no decelerations (less than 110 beats per minute) in a 5 minute CTG strip.

What is admission CTG?
It is done on admission of all pregnant or labouring patient, it helps in picking any risk factors, predicts outcome of labour and does not increase risk of Caesarean delivery, so it’s a very important initial investigation.

What are the indications of continuous CTG?
There are some high risk cases which require continues monitoring of baby heart rate: 

• High blood pressure (pre-eclampsia) during pregnancy 
• Diabetes mellitus
• Twin pregnancy
• Premature delivery 
• Post date pregnancy 
• Heavy bleeding during labour
• Infections with fever
• Baby has passed motion in uterus (meconium stained liquor)
• Ruptured membranes for more than 24 hours 
• Epidural anaesthesia or after top up dose of anaesthesia 
• Use of oxytocin during labour

Does CTG change in labour?
During contractions, heart rate of baby slows but not less than 110 per minute, it recovers quickly after contractions finish. There are certain patterns of CTG which really guide about fetal well being.

• Heart rate less than 110 per minute or more than 160 beats per minute show fetal distress.
• If during contraction heart rate drops to less than 110 per minute and recovers after contraction, its called type 1 dip. 
• If fetal heart drop persists after contraction then its type 2 dip, requiring urgent delivery. 
• There are also certain irregular, variable dips not corresponding to uterine contractions which also indicate a problem.

Are there any side effects of CTG?
These are ultrasound waves, not using any radiation, therefore it’s safe for mother and baby.

Remember fetal heart rate monitoring by CTG has proven to save lives and reduces still-birth rate.

Dr. Ayesha Azam Khan