8A) Antenatal Care: Small-for-gestational age Flashcards
Definition SGA
EFW/AC <10th centile
Definition severe SGA
EFW/AC <3rd centile
Definition low birthweight
<2500g
Types of SGA
Constitutional.
Non-placenta mediated growth restriction.
Placenta mediated growth restriction.
What percentage of SGA babies are constitutionally small?
50-70%
What is the risk assessment process for SGA?
If 3 or more minor risk factors —> uterine artery Doppler 20-24 weeks. If normal - one scan in third trimester. If abnormal serial scans 26-28 weeks.
If one major risk factor OR SFH unsuitable (BMI >35, fibroids) —> Serial scans 26-28 weeks.
What are the minor risk factors for SGA?
Age 35 or more Smoking 1-10 cigarettes Nulliparous Inter pregnancy interval <6m Inter pregnancy interval >60m Previous PET IVF Singleton Poor fruit intake pre-pregnancy BMI <20 BMI 25-35
What are the major risk factors for SGA?
Low PAPP-A (<0.4MoM, <5th centile) Fetal echogenic bowel Age >40 Smoking 11 or more cigarettes Cocaine Daily vigorous exercise Maternal SGA Paternal SGA Previous SGA Previous stillbirth Diabetes with vascular disease Renal disease Chronic hypertension APLS Heavy bleeding like menses
How to monitor confirmed SGA on ultrasound?
- SGA with normal umbilical artery doppler
- Twice weekly growth and doppler
- From 32 weeks also MCA doppler - SGA with raised PI/RI (>2SD)
- Weekly growth
- Twice weekly doppler - SGA with absent or reversed EDF
- Weekly growth
- Daily Doppler
- Before 32 weeks DV (if unavailable then cCTG), after 32 weeks MCA
When to deliver SGA babies?
- SGA with normal umbilical artery Doppler
- Offer delivery by 37 weeks
- Recommend delivery by 37 weeks if MCA Doppler abnormal
- Consider delivery >34 weeks if static growth over 3 weeks - SGA with raised PI/RI
- Offer delivery by 37 weeks
- Consider delivery >34 weeks if static growth over 3 weeks - SGA with AREDV
- Recommend delivery before 32 weeks if abnormal DV or cCTG (provided >24weeks and >500g)
- Recommend delivery by 32 weeks
- Consider delivery 30-32 weeks even if DV normal
What are the relative risks associated with feral echogenic bowel?
2 x risk SGA
9 x risk death
What do abnormalities of the uterine artery Doppler suggest?
Persistent notching or abnormal flow velocity (PI >95th centile) associated with inadequate trophoblast invasion of spinal arteries.
What can uterine artery Doppler predict?
Moderate predictive value for severely SGA neonate.
When to repeat uterine artery Doppler?
Don’t! Even if it normalises there is high risk of SGA.
When should SFH measurements be performed and when should they trigger a scan?
Every appointment from 24 weeks.
If <10th or slowed/static —> ultrasound.
How to determine growth velocity?
If only two measurements should be at least 3 weeks apart.
What investigations should be performed if severe SGA identified?
- If severe SGA at 20 week scan —> FMU anatomy scan and uterine artery Doppler
- If severe SGA and structural abnormality or severe SGA before 23/40 —> Karyotype
- Screening for CMV and toxoplasmosis (+ syphilis/malaria if high risk)
What percentage of severe SGA before 23 weeks or with structural abnormalities will have a chromosomal problem?
20%
What percentage of severe SGA will have an underlying infection?
5%
What is the risk of unidentified SGA compared to identified SGA?
4 x increased risk
When should someone stop smoking by to reduce their risk of SGA to that of a non-smoker?
15 weeks
When should antiplatelets be started in someone at high risk for PET?
Before 16 weeks (RR 0.5 SGA)
What is the primary surveillance tool for SGA babies?
Umbilical artery doppler
Measurement of amniotic fluid in SGA babies should be via which method
DVP
Predictive value of MCA Doppler
For term babies.
Moderate predictive value for acidosis at birth.
Predictive value of DV Doppler
For preterm babies.
Moderate predictive value for acidosis at birth and adverse outcome.
Risk of neonatal morbidity in SGA infant with normal dopplers
2 x higher than normally grown baby
How to deliver a baby with abnormal Doppler?
CS
What is the abnormality seen in the umbilical artery doppler?
Raised pulsatility index/resistance index.
OR absent or reversed end diastolic flow.
What is the abnormality seen in the MCA doppler?
Increased diastolic flow and a reduction in PI.
Cerebro-placental ratio: MCA PI/UA PI
What is the abnormality seen in the ductus venous doppler?
Absence of, or reversal of, the “a” wave.
What is the abnormality seen in the uterine artery doppler?
Raised PI/RI or “notching”
By what time period does an abnormal umbilical artery doppler waveform usually precede acute deterioration?
12 days