Cardiotocography

Question 1

What is CTG used for

Answer 1

Measure the fetal heart rate and the contractions of the uterus

Question 2

How is CTG done

Answer 2

Two transducers are placed on the abdomen to get the CTG readout:

• One above the fetal heart to monitor the fetal heartbeat
• One near the fundus of the uterus to monitor the uterine contractions

Question 3

How does CTG work

Answer 3

The transducer above the fetal heart monitors the heartbeat using Doppler ultrasound.

The transducer above the fundus uses ultrasound to assess the tension in the uterine wall, indicating uterine contraction.

Question 4

Indications for Continuous CTG Monitoring

Answer 4

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

Question 5

Key features to look for on CTG

Answer 5

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

Question 6

What do contractions show

Answer 6

Activity of labour.

Too few contractions - labour is not progressing.
Too many contractions - uterine hyperstimulation

Question 7

Baseline rate

Answer 7

Reassuring - 110 - 160

Non reassuring - 100 - 109 or 161 - 180

Abnormal - < 100 or > 180

Question 8

Variability

Answer 8

Reassuring - 5 - 25

Non reassuring:

• Less than 5 for 30 – 50 minutes or
• More than 25 for 15 – 25 minutes

Abnormal:

• Less than 5 for over 50 minutes or
• More than 25 for over 25 minutes

Question 9

Decelerations

Answer 9

Fetal HR drops in response to hypoxia to conserve oxygen.

Question 10

Types of deceleration

Answer 10

There are four types of decelerations to be aware of:

Early decelerations
Late decelerations
Variable decelerations
Prolonged decelerations

Question 11

Early decelerations

Answer 11

Gradual dips and recoveries in heart rate that correspond with uterine contractions.

The lowest point of the declaration corresponds to the peak of the contraction.

Normal and not considered pathological - caused by the uterus compressing the head the fetus, stimulating the vagus nerve of the fetus, slowing the heart rate

Question 12

Late decelerations

Answer 12

Gradual falls in heart rate that starts after the uterine contraction has already begun.

There is a delay between the uterine contraction and the deceleration.

The lowest point of the declaration occurs after the peak of the contraction.

Caused by hypoxia in the fetus - more concerning finding.

Question 13

What can cause late decelerations

Answer 13

Excessive uterine contractions
Maternal hypotension
Maternal hypoxia

Question 14

Variable decelerations

Answer 14

Abrupt decelerations that may be unrelated to uterine contractions.

Fall of more than 15 bpm from the baseline

The lowest point of the declaration occurs within 30 seconds, and the deceleration lasts less than 2 minutes in total.

Often indicate intermittent compression of the umbilical cord, causing fetal hypoxia

Brief accelerations before and after the deceleration are known as shoulders, and are a reassuring sign that the fetus is coping

Question 15

Reassuring CTG

Answer 15

No decelerations, early decelerations or less than 90 minutes of variable decelerations with no concerning features.

Question 16

Non-reassuring or abnormal

Answer 16

Regular variable decelerations and late decelerations

Question 17

Suspicious CTG

Answer 17

Single non-reassuring feature

Question 18

Pathological CTG

Answer 18

2 non-reassuring features or a single abnormal feature

Question 19

Need for urgent intervention

Answer 19

Acute bradycardia or prolonged deceleration of more than 3 minutes

Question 20

Management of an abnormal CTG

Answer 20

Escalating to a senior midwife and obstetrician

Further assessment for possible causes, such as uterine hyperstimulation, maternal hypotension and cord prolapse

Conservative interventions - repositioning the mother or giving IV fluids for hypotension

Fetal scalp stimulation (an acceleration in response to stimulation is a reassuring sign)

Fetal scalp blood sampling to test for fetal acidosis

Delivery of the baby (e.g. instrumental delivery or emergency caesarean section)

Question 21

Fetal Bradycardia

Answer 21

3 minutes – call for help
6 minutes – move to theatre
9 minutes – prepare for delivery
12 minutes – deliver the baby (by 15 minutes)

Question 22

Sinusoidal CTG

Answer 22

Can indicate severe fetal compromise

Gives a pattern similar to a sine wave, with smooth regular waves up and down that have an amplitude of 5 – 15 bpm.

Associated with severe fetal anaemia -
caused by vasa praevia with fetal haemorrhage

Question 23

DR C BRaVADO

Answer 23

DR – Define Risk (define the risk based on the individual woman and pregnancy before assessing the CTG)

C – Contractions

BRa – Baseline Rate

V – Variability

A – Accelerations

D – Decelerations

O – Overall impression (given an overall impression of the CTG and clinical picture)