Master the board step 3

Obstetrics
Symmetric IUGR
Asymmetric IUGR
Fetal Causes Maternal Causes Placental Causes
↓ growth potential
↓ placental perfusion
Etiology
− Aneuploidy
− Hypertension
− Infarction
− Infection (e.g., TORCH)
− Structural anomalies (e.g.,
congenital heart disease,
NTD, ventral wall defects)
− Small vessel disease
(e.g., SLE)
− Malnutrition
− Tobacco, alcohol, street
drugs
− Abruption
− Twin-twin transfusion
− Velamentous cord insertion
Ultrasound ↓ in all measurements ↓ abdomen measurements; normal head measurements
Workup
− Detailed sonogram
− Karyotype
− Screen for fetal infections
− Monitor with serial sonograms, nonstress test, amniotic fluid
index (AFI), biophysical profile, and umbilical artery Doppler
− AFI is often decreased, especially with severe uteroplacental
insufficiency
Symmetric IUGR is caused by intrinsic factors (e.g., genetic issue, fetal infection).
Asymmetric IUGR is caused by extrinsic factors, such as low oxygen and
nutrient transfer from the placenta leading to hypoxia in the fetus. These
conditions can lead to hypoglycemia (from ↓ glycogen and fat stores) and
polycythemia (from ↑ erythropoietin).
Macrosomia
Macrosomia is indicated by a fetus with estimated fetal weight (EFW) > 90−95
percentile for gestational age or birth weight of 4,000−4,500 g.
Risk factors include the GDM, overt diabetes, prolonged gestation, obesity,
↑↑ in pregnancy weight gain, multiparity, and male fetus.
Complications include:
··
Maternal: Injury during birth, postpartum hemorrhage, and emergency
cesarean section
··
Fetus: Shoulder dystocia, birth injury, asphyxia
··
Neonate: Hypoglycemia, Erb palsy
Management: Elective cesarean (if EFW > 4,500 g in diabetic mother or >
5,000 g in nondiabetic mother)
445