Fetal Monitoring

Question 1

What are the methods used for fetal monitoring?

Answer 1

Fetal movement chart (kick chart)

CTG (also known as non stress test)

Umbilical aa doppler

Contraction stress test (fetal heart rate in response to an artificially stimulated a contraction)

Vibroacoustic stimulation (fetal heart rate in response to vibro-acoustic stimulus)

Maternal blood tests (pregnancy associated plasma protein A: PAPPA) If high in the absence of anomalies suggests high risk pregnancy

Question 2

When is CTG indicated?

Answer 2

During high risk labours.

In women at a high risk of uteroplacental insufficiency whom have reduced fetal movement.

Question 3

What factors will increase the risk of uteroplacental insufficiency?

Answer 3

Maternal disease:
Anaemia
Cardiovascular disease
Renal disease
HTN
Diabetes 
Collagen vascular diseases

Pregnancy:
Post term pregnancy 
Multiple pregnancy 
APH
Advanced maternal age
IUGR baby

Question 4

Which 2 interventions should be started at 28 weeks in women with an increased risk of uteroplacental insufficiency?

Answer 4

Fetal kick chart

CTG (weekly) +/- amniotic fluid estimation weekly

Question 5

What important features are you looking for a normal CTG?

Answer 5

Normal baseline of 110-160

Variability greater than 5 small beats

Accelerations (greater than 15bpm for 15secs

If actively labouring 3 contractions lasting 40-60s in 10mins

Question 6

What features of a CTG are worrying?

Answer 6

Decelerations (early, variable and late)

Bradycardia less than 120bpm is mild
Less than 80 is severe

Sinusoidal pattern

Question 7

Describe the different types of decelerations and give potential causes?

Answer 7

Early decelerations:
Start with contractions and quickly recover as contraction ends. Due to increased intracranial pressure causing a fetal vagal response. This is physiological.

Variable:
Rapid drop from baseline rate followed by a variable recovery period. Often mild acceleration (shoulders) before deceleration.

Causes:

• Umbilical cord compression (brief rise in HR is due to venous compression 1st before aa compression), may resolve if mother changes position.
• If no accelerations prior to the deceleration (shoulders) more likely to be foetal hypoxia.

Late decelerations:
Late decelerations begin at the peak of uterine contraction and recover after the contraction ends.

This type of deceleration indicates there is insufficient blood flow through the uterus and placenta.

As a result blood flow to the foetus is significantly reduced causing foetal hypoxia and acidosis.

Question 8

How should you manage variable and late decelerations?

Answer 8

Variable: change maternal position, consider closer monitoring

Late:
Check fetal pH if acidotic emergency c-section

Question 9

Describe the priniciple behind umbilical doppler velocimetry?

Answer 9

Umbilical aa doppler measurement reflect resistance of blood flow from the foetus to the placenta.

Absent or reseversed diastolic flow is associated with a poor perinatal outcome in the setting of IUGR and indicates urgent delivery.

Essentially helps identify which small for gestational age foetuses are growth restricted.

Question 10

Describe the principle doppler velocimetry of the fetal circulation?

Answer 10

Umbilical aa measurements of the middle cerebral aa and thoracic vessels.

Low resistance flow in the MCA in comparison to thoracic vessels indicates head sparing in IUGR.

Increased flow velocity is also a sign of fetal anaemia.

Question 11

When can uterine aa doppler’s be used?

Answer 11

At 12 or 23 weeks in pregnancies which are very high risk .

Question 12

What is the maximum frequency of USS which can be useful?

Answer 12

Fortnightly more than this and too soon to see changes.