IUGR + Macrosomia Flashcards
What is IUGR?
When growth has slowed or is less than expected due to a growth restriction.
Note: not the same as Small for gestational age
What are the fetal causes of IUGR? (4)
Chromosomal abnormalities (trisomys and turners)
Single gene defects (dwarfism, phenylketonuria)
Multiple pregnancies
Congenital infection
What are the uteroplacental causes of IUGR? (4)
Chronic hypertension/Pre-eclampsia
Antiphospholipid syndrome
Chronic placental abruption
Unexplained chronic proteinuria
What are the maternal causes of IUGR? (3)
Drugs/toxins (cocaine/smoking)
Malnutrition
Maternal chronic illness
What are the main complications of IUGR?
Increased mortality
CP
Learning disabilities
Necrotising enterocolitis
Hypoglycaemia
What is the US diagnostic criteria for IUGR?
-Estimated fetal weight is less than the 5th centile (2 standard deviations from the mean for gestational age)
OR
-Estimated fetal weight is less than 10th centile for gestational age and there is evidence of fetal compromise
If suspected followed up with serial scans, urinalysis and BP are closely monitored due to the strong link between IUGR and pre-eclampsia
What are suggestions that there is fetal compromise?
Oligohydraminos (baby isn’t seeing therefore reduced fluid)
Abnormal umbilical aa doppler blood flow.
When do you not need to intervene in suspected IUGR?
Monitor growth. If growth is consistent and umbilical aa doppler is normal no intervention is needed.
How do you manage IUGR? (5 points)
- Attempt to work out aetiology
- Regular (twice weekly) fetal testing. (umbilical aa doppler, CTG) Monitor growth more regularly every 1 or 2 weeks.
- Consider delivery (induction or elective c-section) once a favourable gestational age greater than 34 weeks. Or if there is a deterioration in fetal markers.
- 50-80% of IUGR foetuses will develop fetal distress during labour and require emergency c-section
- Send placenta and membranes to pathology after delivery.
What is the pathophysiology of uteroplacental IUGR?
- Compromise in uteroplacental blood flow.
- Decreased nutrients to the foetus
- Fetal growth begins to diminish in a fixed sequence. (subcutaneous tissue, axial skeleton, vital organs)
- Nutrient oxygen and energy demands of the growing foetus exceeds supply leading to hypoxia, acidosis and death.
How does the fetal testing reflect the pathophysiology of uteroplacental IUGR?
Compromised blood flow:
-Umbilical aa systolic/diastolic ratio increases: (as diastolic flow decreases/reverses due to increased vascular resistance.)
Growth diminishing:
-Fetal growth on US slows or stops.
Organs become affected:
- Oligohydraminos develops due to diminished perfusion of the kidneys.
- Loss of fetal heart rate variability and decelerations on CTG
Still birth/Intrauterine death
How is macrosomia defined?
Estimated fetal weight greater than 4500g
What re the risk factors for developing macrosomia?
Maternal diabetes
Maternal obesity
Prior macrocosmic children
Post term pregnancy
Beckwith Wiedmann syndrome (overgrowth + childhood Ca + congenital abnormalities)
How can macrosomia be prevented?
Most common cause is due to gestational diabetes therefore meticulous control of diabetes can reduce incidence of macrosomia.
What are the risk factors associated with macrosomia?
Maternal trauma during labour (perineal trauma, PPH)
Increased risk of shoulder dystocia
Increased risk of intrauterine death/neonatal death
Risk of post part hypoglycaemia
