Fetal Monitoring Flashcards
What are the methods used for fetal monitoring?
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
When is CTG indicated?
During high risk labours.
In women at a high risk of uteroplacental insufficiency whom have reduced fetal movement.
What factors will increase the risk of uteroplacental insufficiency?
Maternal disease: Anaemia Cardiovascular disease Renal disease HTN Diabetes Collagen vascular diseases
Pregnancy: Post term pregnancy Multiple pregnancy APH Advanced maternal age IUGR baby
Which 2 interventions should be started at 28 weeks in women with an increased risk of uteroplacental insufficiency?
Fetal kick chart
CTG (weekly) +/- amniotic fluid estimation weekly
What important features are you looking for a normal CTG?
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
What features of a CTG are worrying?
Decelerations (early, variable and late)
Bradycardia less than 120bpm is mild
Less than 80 is severe
Sinusoidal pattern
Describe the different types of decelerations and give potential causes?
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.
How should you manage variable and late decelerations?
Variable: change maternal position, consider closer monitoring
Late:
Check fetal pH if acidotic emergency c-section
Describe the priniciple behind umbilical doppler velocimetry?
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.
Describe the principle doppler velocimetry of the fetal circulation?
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.
When can uterine aa doppler’s be used?
At 12 or 23 weeks in pregnancies which are very high risk .
What is the maximum frequency of USS which can be useful?
Fortnightly more than this and too soon to see changes.
How do read CTGs?
DR C BRaVADO
Define Risk
Contractions
Baseline Rate Variability Accelerations Decelerations Overall impression
What is sinusoidal pattern?
Sign of?
A smooth, regular, wave-like pattern
Frequency of around 2-5 cycles a minute
Stable baseline rate around 120-160bpm
No beat to beat variability
Very concerning as indicates:
Severe fetal hypoxia
Severe fetal anaemia
Fetal/maternal haemorrhage
