8A) Antenatal Care: Small-for-gestational age Flashcards

1
Q

Definition SGA

A

EFW/AC <10th centile

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2
Q

Definition severe SGA

A

EFW/AC <3rd centile

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3
Q

Definition low birthweight

A

<2500g

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4
Q

Types of SGA

A

Constitutional.
Non-placenta mediated growth restriction.
Placenta mediated growth restriction.

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5
Q

What percentage of SGA babies are constitutionally small?

A

50-70%

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6
Q

What is the risk assessment process for SGA?

A

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.

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7
Q

What are the minor risk factors for SGA?

A
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
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8
Q

What are the major risk factors for SGA?

A
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
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9
Q

How to monitor confirmed SGA on ultrasound?

A
  1. SGA with normal umbilical artery doppler
    - Twice weekly growth and doppler
    - From 32 weeks also MCA doppler
  2. SGA with raised PI/RI (>2SD)
    - Weekly growth
    - Twice weekly doppler
  3. SGA with absent or reversed EDF
    - Weekly growth
    - Daily Doppler
    - Before 32 weeks DV (if unavailable then cCTG), after 32 weeks MCA
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10
Q

When to deliver SGA babies?

A
  1. 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
  2. SGA with raised PI/RI
    - Offer delivery by 37 weeks
    - Consider delivery >34 weeks if static growth over 3 weeks
  3. 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
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11
Q

What are the relative risks associated with feral echogenic bowel?

A

2 x risk SGA

9 x risk death

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12
Q

What do abnormalities of the uterine artery Doppler suggest?

A

Persistent notching or abnormal flow velocity (PI >95th centile) associated with inadequate trophoblast invasion of spinal arteries.

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13
Q

What can uterine artery Doppler predict?

A

Moderate predictive value for severely SGA neonate.

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14
Q

When to repeat uterine artery Doppler?

A

Don’t! Even if it normalises there is high risk of SGA.

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15
Q

When should SFH measurements be performed and when should they trigger a scan?

A

Every appointment from 24 weeks.

If <10th or slowed/static —> ultrasound.

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16
Q

How to determine growth velocity?

A

If only two measurements should be at least 3 weeks apart.

17
Q

What investigations should be performed if severe SGA identified?

A
  • 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)
18
Q

What percentage of severe SGA before 23 weeks or with structural abnormalities will have a chromosomal problem?

A

20%

19
Q

What percentage of severe SGA will have an underlying infection?

A

5%

20
Q

What is the risk of unidentified SGA compared to identified SGA?

A

4 x increased risk

21
Q

When should someone stop smoking by to reduce their risk of SGA to that of a non-smoker?

A

15 weeks

22
Q

When should antiplatelets be started in someone at high risk for PET?

A

Before 16 weeks (RR 0.5 SGA)

23
Q

What is the primary surveillance tool for SGA babies?

A

Umbilical artery doppler

24
Q

Measurement of amniotic fluid in SGA babies should be via which method

A

DVP

25
Q

Predictive value of MCA Doppler

A

For term babies.

Moderate predictive value for acidosis at birth.

26
Q

Predictive value of DV Doppler

A

For preterm babies.

Moderate predictive value for acidosis at birth and adverse outcome.

27
Q

Risk of neonatal morbidity in SGA infant with normal dopplers

A

2 x higher than normally grown baby

28
Q

How to deliver a baby with abnormal Doppler?

A

CS

29
Q

What is the abnormality seen in the umbilical artery doppler?

A

Raised pulsatility index/resistance index.

OR absent or reversed end diastolic flow.

30
Q

What is the abnormality seen in the MCA doppler?

A

Increased diastolic flow and a reduction in PI.

Cerebro-placental ratio: MCA PI/UA PI

31
Q

What is the abnormality seen in the ductus venous doppler?

A

Absence of, or reversal of, the “a” wave.

32
Q

What is the abnormality seen in the uterine artery doppler?

A

Raised PI/RI or “notching”

33
Q

By what time period does an abnormal umbilical artery doppler waveform usually precede acute deterioration?

A

12 days