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4th Year Obs and Gynae > CTGs > Flashcards

CTGs Flashcards

1
Q

At what gestation can a CTG be used?

A

>27 weeks gestation

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2
Q

What does CTG stand for?

A

Cardiotocography

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3
Q

What is important to remember when interpreting a CTG?

A

You must take into account the overall clinical picture

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4
Q

How does a CTG work?

A
  • Two transducers (using doppler ultrasound) 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
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5
Q

Indications for continuous CTG monitoring in labour

A
  • 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
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6
Q

What are the 5 key features to look for on a CTG?

A

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

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7
Q

Risks to be identified before interpreting CTG

A
  • Induction
  • Small baby
  • PPROM
  • Meconium
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8
Q

What should be noted about contractions on a CTG?

A
  • Are they present?
  • Are they spontaneous or augmented with oxytocin?
  • Are they regular, is there coupling ect?
  • How many in 10 minutes?
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9
Q

What will the contractions on a CTG tell you about the acitivity of labour?

A
  • Too few contractions indicate labour is not progressing.
  • Too many contractions can mean uterine hyperstimulation, which can lead to fetal compromise.
  • It is also important to interpret the fetal heart rate in the context of the uterine contractions.
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10
Q

What are accelerations and what do they indicate?

A

>15 bpm above the baseline rate for 30 seconds

Accelerations are generally a good sign that the fetus is healthy, particularly when occurring alongside contractions of the uterus.

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11
Q

Which 3 features do they NICE guidelines use to categorise a CTG?

A
  • Baseline rate
  • Variability
  • Decelerations
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12
Q

What are the four categories of CTG?

A
  • Normal
  • Suspicious: a single non-reassuring feature
  • Pathological: two non-reassuring features or a single abnormal feature
  • Need for urgent intervention: acute bradycardia or prolonged deceleration of more than 3 minutes
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13
Q

The outcome of the CTG will guide management, such as:

A
  • Escalating to a senior midwife and obstetrician
  • Further assessment for possible causes, such as uterine hyperstimulation, maternal hypotension and cord prolapse
  • Conservative interventions such as 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)
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14
Q

What baseline rate would be described as reassuring, non-reassuring and abnormal?

A

Reassuring 110 – 160

Non-reassuring 100 – 109 or 161 – 180

Below 100 or above 180

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15
Q

What variability would be described as reassuring, non-reassuring and abnormal?

A

Reasssuring 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 25 minutes

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16
Q

Decelerations are a more concerning finding, what causes foetal heart rate to drop?

A

The fetal heart rate drops in response to hypoxia. The fetal heart rate is slowing to conserve oxygen for the vital organs.

17
Q

What are the 4 types of deceleration to be aware of?

A
  • Early decelerations
  • Late decelerations
  • Variable decelerations
  • Prolonged decelerations
18
Q

Early decelerations

What are they?

When does the lowest point occur?

Are the concerning?

What causes them?

A

Early decelerations are 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.

Early decelerations are normal and not considered pathological.

They are caused by the uterus compressing the head the fetus, stimulating the vagus nerve of the fetus, slowing the heart rate.

19
Q

Late decelerations

What are they?

When does the lowest point occur?

Are the concerning?

What causes them?

A

Late decelerations are 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.

Late decelerations are caused by hypoxia in the fetus, and are a more concerning finding.

They may be caused by excessive uterine contractions, maternal hypotension or maternal hypoxia.

20
Q

Variable decelerations

What are they?

When does the lowest point occur and how long do they last in total?

What causes them?

A

Variable decelerations are abrupt decelerations that may be unrelated to uterine contractions. There is a 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.

Variable decelerations often indicate intermittent compression of the umbilical cord, causing foetal hypoxia.

21
Q

What is a reassuring sign that may be seen with variable decelerations?

A

Brief accelerations before and after the deceleration known as shoulders. They are a reassuring sign that the foetus is coping.

22
Q

Prolonged decelerations

What does this mean?

What causes it?

A
23
Q

What decelerations would be seen on a reassuring CTG?

A

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

24
Q

What decelerations would be classed as non-reassuring or abnormal?

A

Regular variable decelerations and late decelerations are classed as non-reassuring or abnormal, depending on the features. Prolonged decelerations are always abnormal.

25
Q

How would you deal with prolonged foetal bradycardia?

A

There is a “rule of 3’s” for fetal bradycardia when they are prolonged:

  • 3 minutes – call for help
  • 6 minutes – move to theatre
  • 9 minutes – prepare for delivery
  • 12 minutes – deliver the baby (by 15 minutes)
26
Q

Sinusoidal CTG

What does it look like?

What causes it?

How would you deal with it?

A

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

It is usually associated with severe foetal anaemia, for example, caused by vasa praevia with foetal haemorrhage.

Deliver baby immediately/

27
Q

What pneumonic is used to assess the features of a CTG in a structured way?

A

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)

4th Year Obs and Gynae (2 decks)

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