IUGR + Macrosomia Flashcards Preview

Obs & Gynae > IUGR + Macrosomia > Flashcards

Flashcards in IUGR + Macrosomia Deck (16):

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)


Maternal chronic illness


What are the main complications of IUGR?

Increased mortality


Learning disabilities

Necrotising enterocolitis



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)


-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)

1. Attempt to work out aetiology

2. Regular (twice weekly) fetal testing. (umbilical aa doppler, CTG) Monitor growth more regularly every 1 or 2 weeks.

3. 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.

4. 50-80% of IUGR foetuses will develop fetal distress during labour and require emergency c-section

5. Send placenta and membranes to pathology after delivery.


What is the pathophysiology of uteroplacental IUGR?

1. Compromise in uteroplacental blood flow.

2. Decreased nutrients to the foetus

3. Fetal growth begins to diminish in a fixed sequence. (subcutaneous tissue, axial skeleton, vital organs)

4. 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


How should you manage a women with a macrocosmic foetus?

-Manage DM
-Serial USS (2-4weekly)

-Do not induce labour (increases risk of C-section and doesn't decrease the risk of shoulder dystocia)

-Elective c-section should be offered for diabetic women with suspected macrosomia and for non diabetics with estimated fetal weight greater than 5000g

-Vaginal delivery can be done but will need anaethetist and neonatal resus team.