Fetal Growth

Question 1

Fetal growth restriction definition (4)

Answer 1

a condition in which the fetus does not reach its
biological growth potential

• Often equated to being small
• Not all small fetuses are growth restricted
• Not all growth restricted fetuses are small

Question 2

How do you define FGR? (3)

Answer 2

• Growth involves increment in a time interval
• Usual method is to plot fetal size against gestation
• Various centile cut-offs are used for diagnosis of SGA

Question 3

Causes of smallness (4)

Answer 3

• Dating problems
• Constitutional
• Primary fetal/environmental
  problem
• Placental insufficiency

Question 4

Fetal/environment smallness factors (5)

Answer 4

• Chromosomal conditions (e.g. Trisomy 18, Triploidy)
• Congenital infections
  (e.g. Rubella, CMV)
• Genetic syndromes
  (e.g. Russell-Silver syndrome)
• Teratogens (e.g. Fetal alcohol syndrome, Drug abuse)
• Maternal problem
  (e.g. Cyanotic CHD

Question 5

Placental insufficiency (3)

Answer 5

• Placenta function is nutrient and gas exchange
• Poor function will lead to:
• Slowing of growth
  *-Hypoxemia → Hypoxia → Asphyxia
• Stillbirth
• Ultrasound used to find evidence of
• Placental dysfunction
• Fetal response to the dysfunction

Question 6

Placental insufficiency: Clinical setting

Question 7

Feto-maternal circulation

Question 8

Doppler flow basics

Question 9

preg. doppler flow assessment

Question 10

FGR changes in doppler flow

Question 11

Placenta mediated FGR definitions

Question 12

Detecting FGR (3)

Answer 12

• Clinical: Symphysis-fundal height
• Serial ultrasound biometry
• Uterine artery Doppler screening

Question 13

Symphysis-fundal height (3)

Answer 13

• One trial w/ 1639 women was available
• Antenatal detection of small babies was
  lower in the fundal height group (28%)
  than abdominal palpation (48%)
• No evidence of improved outcome

Question 14

routine 3rd trim US: (4)

Answer 14

• Eight trials recruiting 27,024 women were included.
• There was no difference in antenatal, obstetric and neonatal
  intervention or morbidity in screened versus control groups.
• There was a slightly higher caesarean section rate in the screened
  group, but this difference did not reach statistical significance.
• Routine late pregnancy ultrasound was not associated with
  improvements in overall perinatal mortality.

Question 15

Pregnancy Outcome Prediction Study (POPS)

Question 16

Preterm FGR (<37 Wks) (2)

Answer 16

• Diagnosis, fetal response and monitoring
  is well characterized
• Pathophysiology and natural history is
  understood

Question 17

Preterm for Doppler changes

Question 18

Monitoring Umbilical artery (2)

Answer 18

• Umbilical artery (UA) Doppler is of proven benefit

The authors conclude that the use of Doppler ultrasound on the umbilical artery in high-risk pregnancies reduces the risk of perinatal deaths and may result in fewer obstetric interventions.

Question 19

FGR: 28– 36wks (5)

Answer 19

• Increased PI in UA is abnormal
• Deliver for reversed EDF at 32 weeks
• Deliver for absent EDF at 34 weeks
• Deliver for PI > 95th at 37 weeks

NB. MCA Dopplers not needed (less than 37 weeks) if UA Dopplers are normal

Question 20

Truffle - when to deliver (<32wks) (6)

Answer 20

• Early FGR <32 weeks = risk of IUD vs risk of prematurity
• Ideal monitoring modality shown by the Trial of Umbilical
  and Fetal Flow in Europe (TRUFFLE) study
• Included women with singleton at 26–32 weeks of gestation with FGR
• 503 of 542 eligible women were randomly allocated to 3
  monitoring groups
• 12 fetuses (2%) died in utero and 27 (6%) neonatal deaths
  occurred (92% survival)
• More infants delivered due to late ductus changes were free of neuro-impairment

Question 21

Truffle: delivery criteria (3)

Answer 21

cCTG:
STV < 3.5msecs (<29w) or
STV <4msecs (>29w)
on two occasions on the
same day

Early DV:
Abnormal DV PI
(on two occasions on the
same day)

Late DV:
DV a-wave
Absent/reversed
(on two occasions on the
same day)

Question 22

COMPUTERISED CARDIOTOCOGRAPHY (cCTG)

Question 23

DUCTUS VENOSUS DOPPLER (3)

Answer 23

Normal:
Absent a wave:
Reversed a wave:

Question 24

FGR ≥ 37wks (6)

Answer 24

• Increased PI in Umbilical artery is abnormal = DELIVER
• Normal Umbilical artery PI alone is not enough
• MCA Dopplers needed even if Umbilical artery Dopplers are normal
• Deliver if MCA PI < 5th centile
• At EFW <3rd centile, deliver at 37 weeks
• At EFW 3rd – 10th centile, deliver at 39weeks

Question 25

Term GDR + neurodev. (4)

Answer 25

• Several studies show a link b/w small fetuses and abnormal neurodevelopment
• Etiology of subnormal development is
  unclear?- hypoxic injury
• Among babies born at term, being SGA is associated with lower scores neurodevelopmental outcomes compared to
  AGA controls.
• The standardized neurodevelopmental score in SGA babies was 0.32 SD (95% CI, 0.25–0.38) below those for normal controls.

Question 26

Impact of smallness (4)

Answer 26

• Small fetuses often remain small later in life
• Morbidity linked to smallness
• Higher cerebral palsy rates
• Genetic imprinting – genetic basis of adult disease

Question 27

Treatment Options controversy (2)

Answer 27

• Sildenafil might improve fetal growth in utero by vasodilation.
• Dutch STRIDER trial was stopped after 183 women were recruited; this decision was in response to concerns about a higher than expected neonatal mortality (19/71
  [27%] with sildenafil vs 9/63 [14%] with placebo) and high rates of
  persistent pulmonary hypertension of the neonate (PPHN) in the
  sildenafil group (17/64 [27%] sildenafil vs 3/58 [5%] placebo)

Question 28

Unanswered q’s (3)

Answer 28

• Delivery timing for IUGR between 34 – 37 weeks: A trial is ongoing (TRUFFLE-2)
• Monitoring for fetal well-being at term
• What outcome variable is most important: survival, morbidity,
  neurodevelopmental score, adult health

Question 29

Summary (6)

Answer 29

• Discuss the causes of a small fetus
• Define the concept of fetal growth restriction (FGR)
• Pathophysiology of poor placentation using Doppler assessment
• Methods of detecting FGR
• Diagnostic and management differences between preterm and term FGR
• Describe adverse consequences of FGR