FGR/SGA

Question 1

Definition of SGA and FGR.

Answer 1

• Small for gestational age (SGA) Estimated fetal weight/birthweight less than 10th centile
• Fetal Growth Restriction (FGR) A fetus that has not reached its growth potential, most commonly due to placental insufficiency. Absolute definition controversial.

• Severe FGR: Often SGA <3rd centile, features such as oligo/abnormal dopplers etc (oligohydramnios late sign of poor placental perfusion).

• Early onset: <32 weeks gestation
• Late onset: >32 weeks

Question 2

When to suspect suboptimal fetal growth?

Answer 2

• The abdominal circumference on the population (ASUM) scan chart is <5th centile
• Discrepancy in HC and AC
• AC is >5th but is crossing centiles by > 30th centile e.g. reduction from 50th centile to 20th centile
• A change in AC of <5mm over 14 days
• EFW on GROW is <10th
• EFW on GROW is crossing centiles with > one third reduction in EFW percentile

Question 3

What information should be gained from women with suspected FGR?

Answer 3

1. maternal characteristics and medical history (a history of a previous SGA or stillborn infant; maternal age >40; maternal or paternal history of being SGA at birth; smoking >10 cigarettes daily; using cocaine, and maternal diseases associated with increased risk (e.g. chronic hypertension, renal disease, diabetes with vascular disease, anti-phospholipid syndrome)
2. previous obstetric history (3x increased risk)
3. risk factors that may arise in pregnancy (low PAPP-A, heavy early pregnancy bleeding, fetal echogenic bowel, preeclampsia, severe pregnancy-induced hypertension, unexplained APH or abruption and low gestational weight gain)

Question 4

Prevention

Answer 4

Start low dose aspirin (100-150mg) in those with risk factors for FGR if <16/40

Question 5

What factors indicate regular growth scans rather than relying on SFH?

Answer 5

.Raised BMI
large fibroids
prev SGA
HTN disorder 
Multiple pregnancy

Question 6

Suspicion FGR, which investigations?

Answer 6

PET screen including urine,
USS growth +/- dopplers,
CTG,
TORCH and karyotyping if early onset severe SGA (especially if uterine/umbilical dopplers normal),
Consider fetal abnormality/chromosomal causes also in early onset.

Question 7

How to manage babies once born if the have FGR/SGA?

Answer 7

• Monitoring and maintenance of oxygenation, temperature and blood glucose levels.
• Paired cord blood gases can be undertaken to assess acid base status at birth.
• In the care of the preterm growth restricted neonate, consider specific issues relating to prematurity such as lung disease, increased risk of infection, neurological complications and necrotising enterocolitis.
• Term babies at increased risk of hypothermia, hypoglycaemia and jaundice

Question 8

Advice for future pregnancies?

Answer 8

Adjust any modifiable risk factors (e.g. smoking), aspirin for future pregnancies, serial growth scans
Uterine artery doppler

Question 9

What does umbilical artery doppler measure?

Answer 9

Umbilical artery Doppler provides a measure of placental resistance.

Question 10

What does MCA doppler measure?

Answer 10

MCA provides information about cerebral redistribution of blood flow, abnormal MCA is a response to hypoxia and means there is an increased proportion of flow to the brain- brain sparing.

Question 11

What does DV doppler measure?

Answer 11

DV provides information about cardiac redistribution- abnormal DV associated with imminent fetal death.

Question 12

Technique for UA doppler assessment?

Answer 12

• Free loop of cord (away from insertions)
• No fetal body, limb or breathing movements
• Identify UA with colour Doppler
• Measure FVW with pulsed Doppler
- set gate size to cover entire vessel
- Ideally display arterial and venous waveforms simultaneously
• Adjust Doppler gain, baseline, scale and sweep speed to produce a good quality FVW
• Analyse FVW to calculate S/D ratio or PI

Question 13

Indications for measuring uterine artery doppler

Answer 13

• In women assessed to be at high risk of severe or early SGA
E.g:
- previous early SGA with delivery <34/40,
- antiphospholipid syndrome,
- severe chronic HTN,
- maternal renal disease
- an autoimmune condition)

Question 14

Which gestation to perform uterine artery dopplers as screening?

Answer 14

20-24/40

Question 15

Significance of abnormal uterine artery doppler?

Answer 15

Those with very abnormal uterine artery dopplers have a 60% risk of developing SGA/PET that requires delivery <34/40.

Should have regular scans and maternal surveillance.

Question 16

List maternal medical conditions that predispose to SGA:

Answer 16

• Hypertensive disease
• Renal disease
• Diabetes
• Antiphospholipid syndrome
• Maternal history of SGA

Question 17

List current pregnancy complications/developments that predispose to SGA:

Answer 17

• Preeclampsia
• First trimester bleeding
• Placenta abruption
• APH
• Gestational HTN
• Teratogenic exposure
• Low PAPP-A <0.4 MoM
• Echogenic bowel

Question 18

List maternal risk factors that predispose to SGA:

Answer 18

• Low BMI
• High BMI
• AMA
• Nulliparity
• Smoking
• Substance abuse
• IVF
• Poor diet
• Excessive exercise
• Previous SGA
• Previous stillbirth
• Short interpregnancy interval

Question 19

If UAPI is abnormal in an SGA fetus but delivery is not indicated, how often should you repeat the UAPI?

Answer 19

• Twice weekly if forward EDF.

- Daily if absent or reversed EDF.

Question 20

List the benefits of UAPI surveillance (4):

Answer 20

• Reduction in perinatal deaths RR 0.71
• Reduction in IOLs RR 0.89
• Reduction in Caesarean section RR 0.90
• Reduced use of antenatal resources (monitoring occasions, hospital admissions, inpatient stay).

Question 21

In an SGA fetus with normal UAPI, how often would you repeat the UAPI?

Answer 21

• Every 14 days.

Question 22

When does RCOG recommend delivery of an SGA fetus with static growth over 3 weeks (UAPI normal or abnormal but with forward EDF)?

Answer 22

After 34 weeks.

Question 23

At what gestation should an SGA fetus with reversed EDF but normal DV doppler be delivered by?

Answer 23

30-32 weeks

Question 24

At what gestation should an SGA fetus with absent EDF but normal DV doppler by delivered by?

Answer 24

32-34 weeks

Question 25

At what gestation should an SGA fetus with absent or reversed EDF and reversed/absent A-wave on DV doppler be delivered by?

Answer 25

Between 26-32 weeks

Question 26

Briefly describe the DIGITAT Trial

Answer 26

Aim: To compare the effect of IOL with expectant monitoring for IUGR near term Participants: singleton, > 36/40, suspected IUGR Interventions: Randomised to IOL OR expectant management Conclusion: IOL babies were delivered 10 days earlier and weight less, but NO important differences in adverse outcomes or CS rates

Question 27

Briefly describe the GRIT Trial

Answer 27

Aim: To compare the effect of delivery early with delaying birth for as long as possible Inclusion: Fetal compromise, 24-36/40, UAPI recorded, clinical uncertainty about whether immediate delivery was indicated Intervention: Randomised to Immediate delivery or Delayed deliver until the obstetrician was no longer uncertain Results: No difference in mortality, or developmental quotient of survivors Conclusion: Obstetricians are delivering sick preterm babies at about the correct moment to minimise mortality

Question 28

What is the relative risk of stillbirth in SGA?

Answer 28

4 fold

Question 29

What are the delphi criteria for FGR?

Answer 29

- EFW ≤3rd centile - EFW ≤10th centile with UAPI >95th or uterine art ≥95th - EFW ≤10th centile with Slowing growth ≥50 centiles drop - Slowing growth ≥50 centiles drop with UAPI ≥95th

Question 30

Compare delphi criteria for FGR with traditional criteria of EFW ≤10th centile.

Answer 30

Delphi identifies fewer cases of SGA, but better predicts babies with adverse perinatal outcomes (NICU admission, cord pH < 7.10, 5-min Apgar score < 7, RDS, IVH, neonatal seizures or neonatal death.)

Question 31

What is the controversy in defining FGR?

Answer 31

SMFM definition: - FGR: EFW or AC <10th centile - SGA: newborn with BW <10th centile ISUOG definition: - SGA: EFW or AC <10th should be considered at risk of FGR - Fetal size alone not sufficient for diagnosis of FGR unless • EFW or AC <3rd (sole criteria), or • In early onset FGR: <10th with either >95th Uterine artery PI or Umbilical artery PI • In late onset FGR: 2 out of 3 <10th ; >2 quartiles slowing AC or EFW; CPR <5th or UA >95th

Question 32

What is the risk with livebirth population based growth charts and predicting SGA/FGR?

Answer 32

Livebirth (population) charts systematically under-diagnose fetal growth restriction prior to term. This is because they are based on measurement of birthweights of babies born preterm, which is usually skewed due to many preterm (spontaneous or iatrogenic) being at risk for SGA/FGR. Thus <10th on these charts likely demonstrates an extreme (e.g. <3rd) of healthy ongoing pregnancies.

Question 33

What is the aim of WHO and intergrowth21 charts? What do they show?

Answer 33

‘To present the fetal growth charts for estimated fetal weight and fetal biometry for worldwide use’ - They show optimal fetal growth at different gestations for different ethnicities - Significant contributors to variation in fetal growth: gender, parity, maternal height and weight and country

Question 34

What growth charts are most useful for predicting FGR and adverse outcomes?

Answer 34

Limited evidence suggests customised and WHO charts more sensitive than population based or intergrowth

Question 35

Aetiology and Ix of early onset FGR.

Answer 35

``` Aetiology: • Placental • Infection • Genetic • Structural abnormality ``` SMFM 2020: Advice on early onset FGR Recommendations: -Detailed US should be performed with early onset FGR • 20% associated with fetal or chromosomal abN - Choromosomal microarray when unexplained isolated FGR diagnosed at <32 weeks - Chromosomal microarray when FGR is detected and a fetal abnormality, polyhydramnios or both are present (any gestation) - No Toxo, Rubella or Herpes serology unless other risk factors, but check CMV • Suggest CMV PCR if doing an amniocentesis

Question 36

What are the chronic and acute markers of FGR and outcome in order of presence/acuity?

Answer 36

Chronic (weeks): - Abn uterine artery doppler - UAPI >95th - MCA or CPR <5th Acute (7-10 days): - AEDF UAPI - REDF UAPI - DV >95th - absent/reversed DV a wave OR - Reduced STV CTG <3bpm - BPP ≤4 OR - CTG decelerations

Question 37

Findings of the TRUFFLE Trial.

Answer 37

3 arm randomised clinical trial; n= 542; • Inclusion: 26-32 weeks; <10th, plus abnormal umbilical artery doppler (UPI) • Intervention: Trigger for delivery: • reduced STV on CTG • early DV changes (PI >95th) • late DV changes (absent/ reversed a wave) Primary Outcome: survival free of neuroimpairment at the age of 2 years Safety net: CTG STV in DV group; spontaneous repeated decelerations in all groups; deteriorating maternal condition; REDF >30 weeks; AEDF >32 weeks • Safety net triggered delivery commonly (38% overall; up to 52% in late DV group) Findings: ‘The difference in the proportion of infants surviving without neuroimpairment was non significant at the primary endpoint... of survivors, delivery using late DV changes might improve developmental outcomes at 2 years of age’

Question 38

What are the delivery criteria for early onset FGR?

Answer 38

Delivery criteria - Fetal - 24-25+6: individualise - >26 weeks: • spontaneous persistent unprovoked decels, • altered BPP (≤ 4) - 26-32 weeks: Reversed/ absent a wave DV or ↓STV Delivery criteria - Maternal indication • severe PET/ HELLP at any gestation or Obstetric emergency requiring delivery

Question 39

Sensitivity of SFH and USS biometry for detecting SGA.

Answer 39

SFH = 20% biometry = 57% (NB AC<10th and EFW<10th perform similarly as predictor)

Question 40

What is the utility of routine of 3rd trimester USS for predicting FGR and poor perinatal outcome?

Answer 40

Routine T3 ultrasound increases US diagnosis of SGA/ LGA/ AbN AFV Increased chance of CTG and AFV/ Doppler assessment No difference in rates of SGA at birth No difference in perinatal death

Question 41

SMFM criteria for delivery for late FGR.

Answer 41

‘No consensus on the best approach to management...primarily due to paucity of RCTs and heterogeneity of study populations...’ Recommend delivery at 30-32W with FGR and REDF Recommend delivery at 33-34W if FGR and AEDF Recommend delivery at 37W if FGR (<10th) with abN UA PI or with EFW< 3rd Recommend delivery at 38-9W if EFW 3-10th with N UA PI Recommend Caesarean if AREDF Suggest AGAINST the use of uterine, MCA or DV for ‘routine’ management of Late Onset FGR ``` ============================= Deliver at any gestational age for: • Maternal indication • Repeated unprovoked decelerations • BPP ≤ 4 • Reduced STV <3ms cCTG (ISUOG) ```