FE Clinical Indications & Risk Factors 3 — Questions and Answers
Question 1: A woman with pre-gestational type 1 diabetes has a hemoglobin A1c of 9.5% at conception. Compared to well-controlled diabetes, her fetus has what approximate relative increase in CHD risk?
- No increased risk if she starts insulin
- 2-fold increase
- 5-fold or greater increase (Correct answer)
- Equal risk regardless of glucose control
Correct answer: 5-fold or greater increase
Poorly controlled pregestational diabetes (HbA1c >8-9%) is associated with a 5-fold or greater increase in congenital heart defect risk compared to well-controlled diabetes.
Question 2: Which chromosomal abnormality is most strongly associated with atrioventricular septal defect (AVSD) and should prompt a detailed fetal echocardiogram?
- Trisomy 18 (Edwards syndrome)
- Trisomy 21 (Down syndrome) (Correct answer)
- Monosomy X (Turner syndrome)
- Trisomy 13 (Patau syndrome)
Correct answer: Trisomy 21 (Down syndrome)
Approximately 40-50% of individuals with Trisomy 21 (Down syndrome) have a congenital heart defect, with AVSD being the most characteristic lesion.
Question 3: In a dichorionic-diamniotic twin pregnancy, which specific complication most strongly warrants fetal echocardiography for both twins?
- Discordant fetal growth greater than 15%
- Twin-to-twin transfusion syndrome (TTTS) (Correct answer)
- Different fetal sexes
- Placenta previa
Correct answer: Twin-to-twin transfusion syndrome (TTTS)
TTTS creates significant hemodynamic imbalance: the recipient twin develops cardiomegaly and right heart dysfunction, while the donor twin may have impaired cardiac output.
Question 4: A fetus is found to have a single umbilical artery (two-vessel cord) on routine anatomy scan. What is the primary cardiac concern?
- Single umbilical artery has no cardiac significance
- It is a soft marker associated with an increased risk of structural heart defects (Correct answer)
- It exclusively indicates coarctation of the aorta
- Single umbilical artery only increases risk in diabetic mothers
Correct answer: It is a soft marker associated with an increased risk of structural heart defects
A single umbilical artery is associated with a 5-10% rate of structural cardiac anomalies and warrants targeted fetal echocardiography.
Question 5: Which medication class, if taken in the first trimester, is associated with conotruncal cardiac defects and neural tube defects, requiring fetal echocardiography?
- Selective serotonin reuptake inhibitors (SSRIs)
- Beta-blockers
- Antiepileptic drugs (e.g., valproic acid, carbamazepine) (Correct answer)
- Proton pump inhibitors
Correct answer: Antiepileptic drugs (e.g., valproic acid, carbamazepine)
Valproic acid and other antiepileptic drugs are associated with conotruncal defects (e.g., tetralogy of Fallot) and are established cardiac teratogens.
Question 6: A fetus has an increased nuchal translucency (NT) of 4.5 mm at 12 weeks, with normal chromosomes on amniocentesis. What is the ongoing cardiac risk?
- Normal chromosomes eliminate all cardiac risk
- Elevated NT with normal chromosomes still carries a significant risk of structural heart defects (Correct answer)
- Only trisomy 21 cases with elevated NT have cardiac defects
- NT above 3mm only indicates Down syndrome risk
Correct answer: Elevated NT with normal chromosomes still carries a significant risk of structural heart defects
Even with normal chromosomes, a markedly elevated NT (≥3.5 mm) is independently associated with a substantially increased risk of congenital heart defects.
Question 7: Which of the following scenarios represents the correct timing recommendation for fetal echocardiography in a high-risk pregnancy?
- 18-22 weeks gestation for optimal imaging in most high-risk indications (Correct answer)
- 10-12 weeks only, using transvaginal approach
- After 28 weeks when cardiac structures are fully mature
- At any gestational age, as timing has no impact on diagnostic yield
Correct answer: 18-22 weeks gestation for optimal imaging in most high-risk indications
The optimal window for fetal echocardiography is 18-22 weeks gestation when cardiac structures are adequately developed and amniotic fluid allows good acoustic windows.
FE Clinical Indications & Risk Factors 3
A woman with pre-gestational type 1 diabetes has a hemoglobin A1c of 9.5% at conception.
Compared to well-controlled diabetes, her fetus has what approximate relative increase in CHD risk?