Echo KB
Sign in →
← Section IV · Congenital Heart Disease
IV.H

Fetal Echocardiography

7 cards

Notes

Timing

  • Optimal window: 18–20 weeks' gestation.
  • Balances fetal size (large enough to image), amniotic fluid volume (allows visualization), and rib density (thin bones).
  • Fetal cardiac development complete by 8 weeks.

Established indications

  1. Previous child with congenital heart disease.
  2. Maternal history of CHD.
  3. Suspected fetal cardiac arrhythmia.
  4. Fetal hydrops.
  5. Suspected fetal cardiac defect on OB ultrasound (abnormal 4-chamber view).
  6. Suspected non-cardiac anomaly with potential cardiac associations.
  7. Maternal diabetes (increased risk of cardiomyopathy, VSD, transposition).
  8. History of teratogen or drug exposure (lithium - Ebstein's; retinoic acid; anticonvulsants).

What fetal echo detects well

  • Large septal defects (VSD, AVSD).
  • Single ventricle physiology.
  • HLHS.
  • Conotruncal defects with abnormal outflow relationship.
  • Severe valvular stenosis or atresia.

What is harder to detect

  • Small perimembranous VSD - hard to visualize.
  • Secundum ASD - normal fetal PFO can mask.
  • Coarctation - masked by presence of the large fetal ductus.
  • Anomalies of pulmonary venous return.

Fetal circulation review

  • Foramen ovale - right-to-left flow (from IVC to LA).
  • Ductus arteriosus - right-to-left flow (from PA to descending aorta).
  • Ductus venosus - bypasses fetal liver.
  • All four chambers approximately equal size on 4-chamber view.
  • Fetal ventricular pressures approximately equal.

Cards

  • basicIV.H-001
    When is fetal echocardiography optimally performed?
    → At 18–20 weeks' gestation. This balances fetal size (large enough to image), amniotic fluid, and rib ossification.
  • basicIV.H-002
    When is fetal cardiac embryologic development complete?
    → By approximately 8 weeks' gestation. All chambers and outflow tracts are formed.
  • basicIV.H-003
    List four indications for fetal echocardiography.
    → 1) Prior child with CHD or maternal CHD. 2) Suspected fetal arrhythmia or hydrops. 3) Suspected cardiac defect on OB screening ultrasound. 4) Maternal diabetes or teratogen exposure (lithium — Ebstein's; retinoic acid).
  • basicIV.H-004
    Which cardiac lesion is classically hard to detect on fetal echo, and why?
    → Coarctation of the aorta — the large fetal ductus arteriosus supplies flow to the descending aorta and masks the coarctation until postnatal ductal closure.
  • basicIV.H-005
    Which types of ASD are difficult to detect on fetal echo?
    → Secundum ASD — the normal fetal patent foramen ovale (right-to-left shunt) can mimic and mask a true secundum ASD until postnatal life.
  • basicIV.H-006
    Which cardiac abnormality is classically caused by maternal lithium exposure?
    → Ebstein's anomaly of the tricuspid valve.
  • basicIV.H-007
    Which cardiac lesion is associated with maternal diabetes?
    → Hypertrophic cardiomyopathy of the newborn (transient, resolves in the first months of life). Also increased risk of transposition, VSD, and truncus arteriosus.