Women's Health : Small for Gestational Age (SGA) Flashcards
Define the parameters for a baby being labelled as ‘Small for Gestational Age’ (SGA)
Estimated foetal weight less than the 10th centile
What does intrauterine / foetal growth restriction (IUGR / FGR) imply?
Implies a pathological restriction of full genetic growth potential (RCOG definition)
Severe SGA is defined at…
EFW less than 3rd centile
Which 5 measurements are taken as part of surveillance of foetal size?
- Symphyseal fundal height
- Foetal abdominal circumference
- Femur length
- Head circumference / biparietal diameter
- Liquor volume / amniotic fluid index
When is symphyseal fundal height measured?
Regularly at routine antenatal appointments from 24+0 onwards
Normal amniotic fluid index range?
5-25cm
Odds ratio for SGA risk factors?
> 2.0
Name some major risk factors for SGA?
Maternal age, smoking, cocaine, vigorous exercise, previous SGA baby, previous stillbirth, maternal/paternal SGA, chronic HTN, diabetes w/ vascular diseases, antiphospolipid syndrome
Maternal age as SGA risk factor?
> 40
Cigarette count increasing SGA risk?
> 11 per day
Risk factor: maternal vigorous exercise?
Yes, daily
Diabetes with which condition increases SGA risk?
Vascular disease
Minor risk factors for SGA?
Nulliparity, pre-eclampsia
Name some major risk factors for SGA that may occur during pregnancy
Pre-eclampsia, unexplained APH, low maternal weight gain
What is the first line investigation (for SGA) for routine fetal monitoring?
SFH measurement
How is SFH measurement data used?
Plotted on a customised growth chart (Adjusted to maternal height, weight, parity and ethnicity)
What is the second line investigation after SFH measurement (for SGA)?
USS scan
If there is any single major risk factor for SGA, what investigations are asked for?
Serial (2 weekly) USS and umbilical artery Doppler from 26-28 weeks
What indicates further investigation with serial USS?
Any single SFH <10th centile or slow/static growth
Name some further investigations for SGA?
Umbilical artery doppler, CMV and toxoplasmosis screening, MCA Doppler
What would normal low-resistance placenta show on Umbilical Artery Doppler?
Normal low-resistance placenta allows continuous positive flow from foetus to placenta throughout the cardiac cycle (i.e. in systole and diastole)
How would the Umbilical Artery Doppler results change if end-diastolic flow is slowed/reversed?
If end-diastolic flow is slowed / reversed, this suggests increased placental resistance, which implies placental compromise (for example due to pre-eclampsia) and is predictive of SGA
When is CMV and toxoplasmosis screening indicated?
Severe SGA
How is MCA Doppler measured?
Measured compared to umbilical artery flow
MCA Doppler is measured in comparison to…
Umbilical artery flow
How does a hypoxic foetus affect MCA Doppler?
Hypoxic foetus diverts blood flow to the brain to spare cerebral function - this increases MCA diastolic flow in relation to UA diastolic flow
How does foetal anaemia affect MCA Doppler?
MCA flow increases in foetal anaemia
What does RCOG recommend for SGA foetus primary surveillance?
Umbilical artery Doppler
What do current guidelines state, in general, about SGA delivery?
An SGA foetus should be delivered by caesarean section before 37 weeks gestation
When should an SGA foetus be delivered?
Before 37 weeks gestation
What type of delivery is recommended for SGA foetus?
Caesarean section
