Small-for-Gestational-Age Fetus, Investigation and Management

Question 1

who should be assessed for SGA

Answer 1

• All should be assessed at booking for risk factors for SGA fetus/neonate to identify requiring increased surveillance.

Question 2

What is major risk factor for SGA, what is MX

Answer 2

• major risk factor (Odds Ratio [OR] > 2.0)
• referred for serial ultrasound measurement of fetal size and assessment of wellbeing with umbilical artery Doppler from 26–28 wks of pregnancy.

Question 3

What is minor risk factor for SGA, what is MX

Answer 3

• three or more minor risk factors

- referred for uterine artery Doppler at 20–24 wks of gestation.

Question 4

DS marker and SGA predictability

Answer 4

• Second trimester DS markers have limited predictive accuracy for delivery of a SGA neonate.
• low level (< 0.415 MoM) of the first trimester marker PAPP–A should be considered a major risk factor
  for delivery of a SGA neonate.

Question 5

why not uterine artery doppler in high risk population?

Answer 5

In high risk populations uterine artery Doppler at 20–24 wks of pregnancy has a moderate predictive value for severely SGA neonate.

Question 6

why not uterine artery doppler to be repeated risk assessment?

Answer 6

• If abnormal uterine artery Doppler at 20–24 wks, subsequent normalisation of flow velocity indices is still associated with an increased risk of a SGA neonate.
• Repeating uterine artery Doppler is therefore of limited value.

Question 7

What is MX of abnormal uterine artery Doppler at 20–24 weeks?

Answer 7

• abnormal uterine artery Doppler at 20–24 weeks (defined as PI > 95th centile) and/or notching should be referred for serial ultrasound measurement of fetal size & assessment of wellbeing with umbilical artery Doppler commencing at 26–28 weeks of pregnancy.

Question 8

What is MX of normal uterine artery Doppler at 20–24 weeks?

Answer 8

• Women with a normal uterine artery Doppler do not require serial measurement of fetal size and serial
  assessment of wellbeing with umbilical artery Doppler unless they develop specific pregnancy complications, for example antepartum haemorrhage or hypertension.

However, they should be offered a scan for fetal size and umbilical artery Doppler during third trimester.

Question 9

fetal echogenic bowel. & SGA

Answer 9

Serial ultrasound measurement of fetal size and assessment of wellbeing with umbilical artery Doppler
should be offered in cases of fetal echogenic bowel.

Question 10

Abdominal palpation and predictability of SGA

Answer 10

• Abdominal palpation has limited accuracy for prediction of SGA neonate & should not be routinely performed in this context.
• Serial measurement of SFH is recommended at each antenatal appointment from 24 weeks of pregnancy as this improves prediction of a SGA neonate.

Question 11

SFH and predictability of SGA

Answer 11

• SFH should be plotted on customised chart rather than population–based chart as this may improve prediction of a SGA neonate.
• Women with single SFH which plots below 10th centile or serial measurements which demonstrate slow or static growth by crossing centiles should be referred for ultrasound measurement of fetal size.

Question 12

SFH and predictability of SGA & exclusion criteria

Answer 12

• in whom measurement of SFH is inaccurate (BMI > 35, large fibroids, hydramnios) referred for serial assessment of fetal size using ultrasound.

Question 13

Optimum method of diagnosing a SGA fetus and FGR

AC & EFW

Answer 13

• Fetal AC or EFW < 10th centile can be used to diagnose SGA fetus.
• Use of customised fetal weight reference may improve prediction of SGA neonate & adverse perinatal outcome. In women having serial assessment of fetal size, use of customised fetal weight reference may improve prediction of normal perinatal outcome.

Question 14

• Routine measurement of fetal AC or EFW in the third trimester

Answer 14

• Routine measurement of fetal AC or EFW in third trimester does not reduce incidence of a SGA neonate nor does it improve perinatal outcome.
• Routine fetal biometry is thus not justified.

Question 15

Optimum method of diagnosing a SGA fetus and FGR

- Change in AC or EFW

Answer 15

• Change in AC or EFW may improve prediction of wasting at birth (neonatal morphometric indicators)
  and adverse perinatal outcome suggestive of FGR.

Question 16

Growth velocity

Answer 16

• using two measurements of AC or EFW to estimate growth velocity, at least 3 wks apart to minimise false–positive rates for diagnosing FGR.
• More frequent measurements of fetal size appropriate where birth weight prediction relevant outside of context of diagnosing SGA/FGR.

Question 17

reduced Growth velocity

Answer 17

• If fetal AC or EFW is < 10th centile or evidence of reduced growth velocity, offer serial assessment of fetal size and umbilical artery Doppler.

Question 18

when in SGA, detailed fetal anatomical survey & uterine artery Doppler by fetal medicine specialist is indicated ?

Answer 18

• Offer referral, if severe SGA is identified at 18–20 wk scan.

Question 19

when in SGA, karyotyping is indicated ?

Answer 19

• Karyotyping should be offered in severely SGA fetuses with structural anomalies & if detected before 23 wks especially if uterine artery Doppler is normal.

Question 20

when in SGA Serological screening for congenital CMV & toxoplasmosis is indicated ?

Answer 20

• Serological screening for congenital CMV & toxoplasmosis infection offered in severely SGA fetuses.

Question 21

when in SGA Testing for syphilis & malaria is indicated ?

Answer 21

• Testing for syphilis & malaria considered in high risk populations.

Question 22

Uterine artery doppler in 3rd trimester in SGA

Answer 22

Uterine artery Doppler has limited accuracy to predict adverse outcome in SGA fetuses diagnosed during third trimester.

Question 23

Interventions to be considered in the prevention of SGA fetuses/neonates
Aspirin

Answer 23

Antiplatelet agents maybe effective in preventing SGA birth, at high risk of pre-eclampsia although effect size small.

• at high risk of pre-eclampsia, antiplatelet agents commenced at, or before, 16 weeks of pregnancy.

Question 24

Interventions to be considered in the prevention of SGA fetuses/neonates
dietary modification, progesterone or calcium

Answer 24

• no consistent evidence that dietary modification, progesterone or calcium prevent birth of SGA infant.
• These interventions not be used for this indication.

Question 25

Interventions to be considered in the prevention of SGA fetuses/neonates smoking

Answer 25

Interventions to promote smoking cessation may prevent delivery of SGA infant. - The health benefits of smoking cessation indicate that these interventions should be offered to all women who are pregnant and smoke.

Question 26

Interventions to be considered in the prevention of SGA fetuses/neonates Antithrombotic therapy

Answer 26

Antithrombotic therapy appears to be promising therapy for preventing delivery of SGA in high-risk women. - there is insufficient evidence, especially concerning serious adverse effects, to recommend its use.

Question 27

steroid in SGA

Answer 27

- Interventions to be considered in preterm SGA fetus - Women with SGA fetus b/w 24+0 - 35+6 wks, where delivery is being considered, receive single course of antenatal corticosteroids.

Question 28

Optimal method and frequency of fetal surveillance in SGA | - Umbilical artery Doppler in SGA.

Answer 28

- In high–risk population, use of umbilical artery Doppler shown to reduce perinatal morbidity and mortality. - Umbilical artery Doppler primary surveillance tool in SGA. - When umbilical artery Doppler flow indices are normal it is reasonable to repeat surveillance every 14 days. - More frequent Doppler surveillance appropriate in a severely SGA fetus. - When umbilical artery Doppler flow indices are abnormal (PI or RI > +2 SDs above mean for gestational age) and delivery is not indicated repeat surveillance twice weekly in fetuses with end–diastolic velocities present and daily in fetuses with absent/reversed end–diastolic frequencies.

Question 29

Optimal method and frequency of fetal surveillance in SGA | CTG

Answer 29

- CTG should not be used as only form of surveillance in SGA fetuses. - Interpretation of the CTG should be based on short term fetal heart rate variation from computerised analysis.

Question 30

Optimal method and frequency of fetal surveillance in SGA | Ultrasound assessment of amniotic fluid volume

Answer 30

- Ultrasound assessment of amniotic fluid volume should not be used as the only form of surveillance in SGA fetuses. - Interpretation of amniotic fluid volume should be based on single deepest vertical pocket.

Question 31

Optimal method and frequency of fetal surveillance in SGA | Biophysical profile

Answer 31

Biophysical profile should not be used for fetal surveillance in preterm SGA fetuses.

Question 32

Optimal method and frequency of fetal surveillance in SGA | MCA) Doppler

Answer 32

- In the preterm SGA fetus, MCA Doppler has limited accuracy to predict acidaemia and adverse outcome and should not be used to time delivery. - In term SGA fetus with normal umbilical artery Doppler, abnormal middle cerebral artery Doppler (PI < 5th centile) has moderate predictive value for acidosis at birth and should be used to time delivery.

Question 33

Optimal method and frequency of fetal surveillance in SGA | Ductus venosus Doppler

Answer 33

- Ductus venosus Doppler moderate predictive value for acidaemia and adverse outcome. - Ductus venosus Doppler should be used for surveillance in preterm SGA fetus with abnormal umbilical artery Doppler and used to time delivery.

Question 34

The optimal gestation to deliver the SGA fetus

Answer 34

- In the preterm SGA fetus with umbilical artery AREDV detected < 32 wKs, delivery recommended when DV Doppler becomes abnormal or UV pulsations appear, provided fetus considered viable and after completion of steroids. Even when venous Doppler is normal, delivery is recommended by 32 weeks of gestation and should be considered between 30–32 weeks of gestation. - If MCA Doppler is abnormal, delivery should be recommended no later than 37 weeks of gestation. - In the SGA fetus detected after 32 weeks of gestation with an abnormal umbilical artery Doppler, delivery no later than 37 weeks of gestation is recommended. - In the SGA fetus detected after 32 weeks of gestation with normal umbilical artery Doppler, a senior obstetrician should be involved in determining the timing and mode of birth of these pregnancies. Delivery should be offered at 37 weeks of gestation.

Question 35

How the SGA fetus should be delivered

Answer 35

- In the SGA fetus with umbilical artery AREDV delivery by caesarean section is recommended. - In SGA fetus with normal umbilical artery Doppler or with abnormal umbilical artery PI but end–diastolic velocities present, induction of labour can be offered but rates of emergency CS are increased & continuous fetal heart rate monitoring is recommended from the onset of uterine contractions. - Early admission is recommended in women in spontaneous labour with SGA fetus in order to instigate continuous fetal heart rate monitoring.