cOGText: CTG

Question 1

Once the membranes rupture, how might the colour of the liquor indicate fetal well-being?

Answer 1

• often meconium stained in cases of fetal distress e.g. obstructed labour, fetal hypoxia
• or it may be a sign of a prolonged pregnancy in a term infant

Question 2

T/F: Meconium may be normal in labour

Answer 2

true - but does provoke further fetal surveillance and monitoring.

Is also associated with breech presentation.

Question 3

T/F: FBS should be undertaken where there there is clear evidence of acute fetal compromise e.g. prolonged deceleration for >3 minutes

Answer 3

Fsalse - FBS should not be undertaken and urgent preparations to expedite birth should be made.

Question 4

What is CTG and when is it used?

Answer 4

• Cardiotocograph (CTG) graphs both fetal heart rate and uterine contractions
• often used when there are risk factors for fetal hypoxia e.g. pre-eclampsia, post-dates gestation, induction of labour, epidural use and prolonged labour.

Question 5

T/F: CTGs are specific and decrease medical intervention

Answer 5

false - they are not specific and do increase medical intervention but fetal heart rates changes should be taken seriously if they occur.

Question 6

Mnemonic for interpreting CTGs?

Answer 6

DR C BRAVADO

Question 7

DR C BRAVADO

Answer 7

Define risk - why is the patient on CTG?

• pre-eclampsia
• antepartum haemorrhage
• maternal obesity
• diabetes
• hypertension
• multiple gestation
• post-dates gestation
• previous c-section
• premature rupture of membranes
• oxytocin induction/augmentation of labour

Question 8

DR C BRAVADO

Contractions

1. represented by what on the page?
2. In established labour expect ?? in 10mins
3. Each large square = __ minutes.
4. T/F: a CTG only demonstrates the frequency of contractions, not strength or effectiveness.

Answer 8

1. shown by peaks at the bottom of the trace
2. 3-5 in 10mins
3. 10 minutes.
4. true

Question 9

DR C BRAVADO

Baseline rate

1. The fetal baseline heart rate should be approximately ____beats per minute.
2. Each large square = __ beats and each small square = __ beats.
3. A fetal bradycardia is below ___ beats per minute and a fetal tachycardia is more than ___beats/min

Answer 9

1. 110-160
2. 10
3. 5
4. 110
5. 160

Question 10

DR C BRAVADO

Variability

1. What is ‘good variability’?
2. Reduced variability?
3. What causes variability?
4. When is it physiologically reduced?
5. What might cause it to be pathologically reduced?
6. A fetal heart rate with a variability <__bpm for more than 90 minutes is abnormal and may indicate fetal compromise.

Answer 10

1. between 5-25 beats per minute
2. is defined as < 5 beats per minute
3. due to the millisecond-to-millisecond reaction of the sympathetic and parasympathetic activity on the heart: reflects the integrity of the autonomic nervous system.
4. Reduced during the fetal sleep state (shouldn’t last for >40minutes)
5. Hypoxia, infection and medication
6. 5

Question 11

DR C BRAVADO

Accelerations

1. What are these?
2. T/F: the presence of these is generally a bad sign
3. There should be __ separate accelerations every 15 minutes and these typically occur with ___ and are considered reassuring as they reflect the activity of the fetal ____ nervous system.

Answer 11

1. rise in fetal HR of at least 15 beats lasting ≥ 15s and are associated with fetal movement.
2. false - presence of fetal heart rate accelerations, even with a reduced baseline variability, is generally a sign that the baby is healthy.
3. 2, contractions, somatic

Question 12

DR C BRAVADO

Decelerations

1. What are these?
2. T/F: they are generally abnormal
3. They are often defined in terms of what
4. What type are particularly worrying

Answer 12

1. Reductions of HR by at least 15 beats for at least 15 seconds.
2. True - should prompt senior review
3. In relation to the uterine contractions i.e. early or late and also by their intensity.
4. In particular, late decelerations which are slow to recover are indicative of fetal hypoxia.

Question 13

Dr C BRAVADO

Overall impression/diagnosis

At undergraduate level, be aware of 2 features

1. Terminal bradycardia: what is this?
2. Terminal deceleration: what is this?
3. These 2 features make up a pre-terminal CTG and are indicators for what intervention?

Answer 13

1. baseline fetal HR drops < 100bpm for >10minutes.
2. HR drops and does NOT recover for more than 3 minutes.
3. Emergency c-section

Question 14

CTGs are often labelled as reassuring, non-reassuring or suspicious and should always be interpreted by a trained member of the obstetric or midwifery team.

1. What are some suspicious changes in a CTG?
2. these changes are sometimes investigated with what?

Answer 14

1. late decelerations, reduced variability, fetal tachycardia
2. fetal scalp blood sampling, looking for acidosis

Question 15

NICE Guideline tables

Answer 15

to add in

Question 16

Early decelerations

1. definition
2. cause
3. management

Answer 16

1. drop in fetal HR >15 bpm for >15 min that occurs at the beginning of the contraction with the nadir occurring at the peak of the contraction. Recover when contraction stops.
2. Often due to head compression during a contraction and increased vagal tone, occurs in late first and second stage of labour
3. Physiological

Question 17

Late decelerations

1. definition
2. cause
3. management

Answer 17

1. Occurs well after the contraction is established and does not return to the normal baseline rate until at least 20s after the contraction is completed.
2. Due to placental insufficiency, may indicate fetal hypoxia. This could be caused by maternal hypotension, pre-eclampsia, uterine hyperstimulation
3. Call senior help, FBS to check for hypoxia, may need to expedite delivery

Question 18

Reduced variability:

1. Definition
2. Cause

Answer 18

1. Variability of <5 bpm for more than 40minutes.
2. Multiple causes – fetal sleeping (no longer than 40mins), fetal acidosis and hypoxia, fetal tachycardia, drugs (opiates, methyldopa, magnesium sulphate), prematurity (variability is reduced at earlier gestation <28weeks), congenital heart problems.

Question 19

Variable decelerations

1. Relationship to uterine contractions?
2. They have a variable ____ phase.
3. Most often seen during labour and in patients with reduced __ __ volume/premature __ __ __
4. HR usually drops by >___ beats/min and is due to __ __ which gives rise to variable shapes, sizes and timing of decelerations (non-reassuring features)
5. They often resemble U, V or W shapes
6. T/F: an increase in the depth and duration of decelerations and a rise in baseline rate and reduction in baseline variability suggests the situation is improving

Answer 19

1. Vary in timing and amplitude and may not have a relationship to uterine contractions.
2. recovery
3. amniotic fluid, rupture of membranes.
4. 40, cord compression
5. false - suggests worsening fetal hypoxia.

Question 20

What causes variable decelerations on a CTG?

Answer 20

• Cord compression which initially compresses the umbilical vein causing acceleration -a healthy response.
• The occlusion of the umbilical artery results in a rapid deceleration. When pressure on the cord is reduced, another acceleration occurs and baseline rate returns.

Question 21

Accelerations before and after a variable deceleration are known as the “_____ of the deceleration” - what do they indicate about the condition of the foetus?

What does variable decelerations without shoulders suggest?

Answer 21

• shoulders
• shoulders indicate the fetus is not yet hypoxic and is adapting to the reduced blood flow.
• no shoulders suggest the fetus is becoming hypoxic

Question 22

Sinusoidal pattern on CTG

1. what is it?
2. what does it look like
3. what underlying pathology does it indicate?
4. management?

Answer 22

1. rare but v concerning feature (associated with fetal mortality and morbidity)
2. smooth, regular wave-like pattern, no beat to beat variability, stable baseline of 120-160bpm, frequency of 120-160bpm
3. Severe fetal hypoxia, fetal anaemia. Fetal/maternal haemorrhage
4. Urgent c-section

Question 23

Intermittent auscultation:

1. Fetal heart rate is monitored every 15 minutes for a period of __ ___ soon after a contraction using a handheld Doppler ultrasound transducer or ____ fetal stethoscope in the 1st stage of labour.
2. In the second stage of labour, the fetal heart rate is auscultated every ___ ___ or after every other contraction for 1 minute and check maternal ____ every 15 minutes.
3. Contractions are monitored by manual palpation over a period of 10 minutes to determine the duration and frequency.

Answer 23

1. 1 minute, Pinard
2. 5 minutes, pulse

Question 24

Fetal acid-base balance

1. When there are abnormalities in fetal heart rate during labour, fetal ____ can occur which can be confirmed by examining fetal pH.
2. An ____ is used to obtain blood from the fetal scalp and the cervix must be at least >__cm dilated to allow insertion of the instrument
3. Normal fetal pH lies between ___ and ___
4. Indications?

Answer 24

1. acidosis
2. amnioscope, 3cm
3. 7.25 and 7.35
4. pathological CTG in labour (dilation >3cm), suspected acidosis in labour (dilatation >3cm)

Question 25

Interpretation and action required if scalp pH is:

1. >7.25
2. 7.20-7.25
3. <7.20

Answer 25

1. Normal; none – monitor CTG
2. Borderline; repeat CTG 30 min
3. Abnormal; deliver [c-section or forceps]

Question 26

Fetal distress can have many causes and signs of this may be seen in abnormal ___ and abnormal __ __ __

Answer 26

CTGs

fetal scalp pH

Question 27

Management of fetal distress?

Answer 27

1. Changing maternal position
2. Maternal assessment – measuring pulse, BP, abdomen palpation and vaginal examinations
3. IV fluids
4. Stopping contractions by stopping/reducing dose of syntocinon and considering terbutaline which acts to relax uterus
5. Scalp stimulation during vaginal examination – a healthy fetus will have an acceleration in response to this.
6. Fetal blood sampling
7. Operative delivery – operative vaginal delivery or caesarean section.