Foetal Growth Restriction Flashcards
FGR
FGR = condition in which the foetus does not reach its biological growth potential
Growth involves increment in a time interval- usual method is to plot foetal size against gestation
Various centile cut offs are used for diagnose of SGA (small for gestational age)
Causes of smallness:
dating problems, constitutional, primary foetal/environment problem, placental insufficiency
Foetal/environmental
Placental insufficiency
Foetal/ environmental
Chromosomal conditions- trisomy 18, triploidy (test via placental biopsy- chorionic villus sample)
In triploidy, baby has big head + placenta tends to be extra big + v vascular, so produces v high hCG levels
High hCG = mother v sick as hCG stimulates vomiting centres
Congenital infections- rubella, CMV
CMV = ventriculomegaly (periventricular shadowing + enlarged ventricles)
Take sample of amniotic fluid + test for CMV
Genetic syndromes- Russell-Silver syndrome
Characterised by poor growth + reduced intellectual activity + low set ears
Teratogens- foetal alcohol syndrome, drug abuse
Maternal problem- cyanotic CHD
If mother is cyanotic, baby will also lack oxygen
Placental insufficiency
Placenta function = gas exchange and nutrition
Poor function leads to: slowing of growth and eventually metabolism, hypoxemia -> hypoxia -> asphyxia, still birth
Ultrasound used to find evidence of: placental dysfunction + foetal response to the dysfunction
Clinical setting:
- Risk factor
- Previous history
- Positive uterine artery - Doppler screen
- Abnormal placental echo-texture
- AC/EFW below the 3rd centile
Placenta mediated FGR: definitions:
Early FGR: GA <32 weeks in absence of congenital anomalies:
AC/EFW < 3rd centile or UA-AEDF
- OR AC/EFW < 10th centile combined w:
- UtA-PI > 95th centile and/or:
- UA-PI > 95th centile
Late FGR: GA > 32 weeks, in absence of congenital anomalies:
AC/EFW < 3rd centile
OR at least 2 out of 3 of the following:
- AC/EFW < 10th centile
- AC/EFW crossing centiles > 2 quartiles on growth centiles
- CPR < 5th centile or UA-PI > 95th centile
What stuff means:
GA = gestational age
AC = abdominal circumference
EFW = estimated foetal weight
UtA-PI = uterine artery pulsatility index
UA-PI = umbilical artery pulsatility index
CPR = cerebroplacental ratio
Foetal-maternal circulation:
Umbilical arteries have deoxygenated blood and travel to placenta
Umbilical vein has oxygenated blood
Ductus venosus shunts the blood through the foramen ovale straight into the left side of the heart and then systemic circulation- first goes to head + neck via carotid, so goes up to brain
Then goes back down descending aorta and back to placental arteries
Doppler looks at placental function + foetal response
Test placental function on maternal and foetal side
Maternal = uterine arteries
Foetal = umbilical arteries- want a low resistance for good perfusion
Consider foetal response too:
Foetal = middle cerebral artery (want high resistance as low resistance means there’s a lack of oxygen), ductus venosus (backflow means there’s no perfusion)
Important things to consider;
Uterines- maternal side of placental function
Umbilical arteries- foetal side of placental function
Foetal response to any hypoxia
Middle cerebral artery- is it compensating?
Is baby decompensating w abnormal ductus venosus?
Doppler-flow basics
Peak = systole, trough = diastole
Big, wide troughs = good as lots of blood returning to placenta = good perfusion, low resistance
Always want forward flow
Reversed flow = backflow, so no gas exchange
Doppler changes in FGR
Low resistance to brain = poor blood flow
Methods for detecting FGR:
Clinical: symphysis-fundal height (not v reliable)
Serial US biometry
Uterine artery Doppler screening
Pre-term (<37 weeks)
Diagnosis, foetal response + monitoring is well characterised
Pathophysiology + natural history is understood
Preterm FGR Doppler Changes:
Umbilical artery resistance increases
MCA resistance lowers = baby is redistributing
Abnormal ductus venosus (+ baby moves less to conserve energy)
Abnormal foetal heart rate
Monitoring-umbilical artery
Umbilical artery (UA) Doppler has proven beneficial
Reduces the risk of perinatal deaths + may result in fewer obstetric interventions
FGR 28-36 weeks
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
** MCA Dopplers not needed (less than 37 weeks) if UA Dopplers are normal
TRUFFLE delivery criteria:
Use this criteria to monitor small babies (<32 weeks) to decide when to deliver them
So: Measure BF to ductus venosus + do heart tracing + then figure out when to give birth
cCTG = STV <3.5mmsecs (<29w) or STV <4msecs (>29w) on 2 occasions on the same day
If STV > 4 = everything’s okay, keep being pregnant + no need to deliver yet
Early DV = abnormal DV PI (on 2 occasions on the same day)
High resistance but normal forward flow
Late DV = DV a-wave absent/reversed (on 2 occasions on the same day)- had better intact survival rate at 2 years
FGR>37 weeks
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 39 weeks
Serious perinatal complications
Stillbirth
Cerebral palsy/disability
IVH/convulsions
HIE grade 2/3
Neonatal convulsions
