Fetal Growth Flashcards
Fetal growth restriction definition (4)
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
How do you define FGR? (3)
- 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
Causes of smallness (4)
- Dating problems
- Constitutional
- Primary fetal/environmental
problem - Placental insufficiency
Fetal/environment smallness factors (5)
- 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
Placental insufficiency (3)
- 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
Placental insufficiency: Clinical setting
Feto-maternal circulation
Doppler flow basics
preg. doppler flow assessment
FGR changes in doppler flow
Placenta mediated FGR definitions
Detecting FGR (3)
- Clinical: Symphysis-fundal height
- Serial ultrasound biometry
- Uterine artery Doppler screening
Symphysis-fundal height (3)
- 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
routine 3rd trim US: (4)
- 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.
Pregnancy Outcome Prediction Study (POPS)
Preterm FGR (<37 Wks) (2)
- Diagnosis, fetal response and monitoring
is well characterized - Pathophysiology and natural history is
understood
Preterm for Doppler changes
Monitoring Umbilical artery (2)
- 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.
FGR: 28– 36wks (5)
- 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
Truffle - when to deliver (<32wks) (6)
- 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
Truffle: delivery criteria (3)
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)
COMPUTERISED CARDIOTOCOGRAPHY (cCTG)
DUCTUS VENOSUS DOPPLER (3)
Normal:
Absent a wave:
Reversed a wave:
FGR ≥ 37wks (6)
- 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
Term GDR + neurodev. (4)
- 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.
Impact of smallness (4)
- Small fetuses often remain small later in life
- Morbidity linked to smallness
- Higher cerebral palsy rates
- Genetic imprinting – genetic basis of adult disease
Treatment Options controversy (2)
- 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)
Unanswered q’s (3)
- 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
Summary (6)
- 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
