SGA and IUGR Flashcards
What is the definition of SGA?
BW <10th centile or AC <10th centile
What is the definition of severe SGA?
BW <3rd centile or AC <3rd centil
______% SGA foetuses are constitutionally small
50-70%
What does fetal growth restriction imply?
Pathological restriction of the genetic growth potential
Fetal compromise
What is the pathophysiology of SGA secondary to placental insufficiency?
Failure of trophoblast invasion of the myometrial uterine spiral arteries
Reduced uteroplacental blood flow
What is the relative risk of SGA, if previous pregnancy affected by SGA?
2
Higher if more than one previous pregnancy affected
What is the relative risk of SGA with a low PAPP-A
3
What are the 6 categories of causes of SGA?
Constitutionally small Structural or chromosomal anomaly Inborn errors of metabolism Infection - TORCH Placental insufficiency Maternal conditions (affecting placenta really)
What is the main risk with SGA?
Increased perinatal mortality and morbidity
Unidentified SGA foetuses have a ___ fold increased risk of adverse outcomes
4
Why should SFH be plotted on a customised chart?
May improve prediction of SGA neonate
What is the management of abnormal uterine artery doppler at 20-24/40
Serial USS measurement and UAPI commencing 26-28/40
Should BPP be used in preterm SGA?
No
STV < 3 is associated with…
Higher rate of metabolic acid anemia and early neonatal death
What was the Cochrane Review finding re: Umbilical artery PI in high risk pregnancies
Pregnancies at risk of placental insufficiency should be monitored with this
UAPI measurement may decrease the
- mortality rate
And lead to fewer IOLs and CS
What does the ductus venosus doppler reflect?
Pathophysiology
Atrial pressure-volume changes during the cardiac cycle
As FGR worsening, velocity reduces in the DV a wave owing to increased afterload and preload, as well as increased end-diastolic pressure
Reflects acid anemia
Retrograde a-wave and pulsatile flow in the UV signifies the onset of overt fetal cardiac compromise
What is the role of MCA PI in preterm SGA?
Not to be used to time delivery (RCOG)
No evidence that it correlates with acid-base physiology
Low predictive value re: adverse outcome
Delivery at 37/40 (RCOG)
What does an abnormal MCA PI represent?
Pathophysiology
Cerebral vasodilation
Redistribution of blood
Brain sparing
What is the gestational cut-off for early vs late onset IUGR
32/40
What was the aim, interventions and outcomes of the DIGITAT trial?
Aim: To compare the effect of IOL with expectant monitoring for IUGR near term
Participants: singleton, 36/40, suspected IUGR
Interventions: IOL vs expectant management. Randomly allocated
Primary outcome: composite neonatal outcome, operative delivery
Results. IOL babies were
- delivered 10 days earlier
- weighed 130g less
- no important differences in adverse outcomes
- no difference in CS rates
What % of FGR babies will experience intrapartum asphyxia?
50%
What is the perinatal mortality rate for FGR babies?
80 per 1000
What % of stillbirths are FGR?
Preterm stillbirth 50%
Term stillbirth 25%
Regarding UAPI:
What are the benefits?
When are they indicated?
How often should they be done?
Reduces:
- Perinatal mortality
- IOL
- CS rate
- Use of hospital resources.
Indications: FGR, RFMs, pregnancy HTN disorders.
Every 2 weeks if normal
Twice a week if abnormal with forward EDF.
Every day if abnormal with absent or reversed EDF.
What are the indications for MCAPI?
- SGA with ABNORMAL doppler, any gestation.
- SGA with NORMAL doppler, only after 34 weeks
- MCDA with TTTS
What is the pathophysiology behind the ductus venosus doppler findings associated with FGR?
Abnormal DVPI >95th cent.
Abnormal DV A-wave is absent or reversed.
DV A-wave represents pressure created by right atrial contraction in late diastolic phase and causes a variable amount of reverse flow.
- Increased umbilical artery resistance –> impaired fetal cardiac performance and increased CVP –> reduced DV diastolic flow and reduction in A-wave.
- Absent or reversed DV A-wave indicates cardiovascular instability and can be a sign of impending acidaemia and fetal death.
What are the benefits of measuring the DV A-wave?
TRUFFLE study: improved 2 year survival without impairment when delivery triggered by absent A-wave.
When should DV doppler (DVPI and A-wave) be measured?
For timing of delivery decision making for PRETERM infants:
- SGA with abnormal UAPI and reduced MCAPI
- MCDA twins with TTTS or sIUGR.
What is the progression of doppler changes in severe IUGR?
Early signs:
- UAPI
- MCAPI
- UA AEDF
Late signs:
- UA REDF
- DVPI
- DV absent or reversed a wave
Describe the role of CTG in the care of preterm SGA fetuses:
Should not be only surveillance method as no improvement in perinatal mortality.
STV from computerised analysis: most powerful predictor of fetal wellbeing.
<=3 ms associated with higher rate of metabolic acidaemia (50 vs 10%) and early neonatal death (8 vs 0.5%).
What the the indications for inpatient mgmt of FGR pregnancies?
- Umbilical artery A/REDF and EFW >350 g
- No fetal growth
- Associated oligohydramnios
- Reduced or absent FMs
In the context of an FGR pregnancy:
When should antenatal corticosteroids be given?
What side-effect can affect fetal surveillance?
Indicated when umbilical artery EDF becomes absent or reversed.
Side-effects:
- Reversed FHR variability
- RFMs by 50%
- Cessation of fetal breathing movements.
- Temporary improvement in doppler studies.
Regarding FGR pregnancy:
What are the indications for delivery and timings (aside from safety net abnormal CTG findings?).
<32 weeks: Abnormal DV doppler, umbilical vein pulsations and/or abnormal cCTG with umbilical artery A/REDF.
- Consider between 30-32 weeks even if DV doppler normal.
By 34 weeks: UAPI EDF
By 37 weeks: UAPI or MCAPI abnormal.
By 38-40 weeks: UAPI normal
After 34 weeks: static growth +/- abnormal UAPI with forward EDF.
