Elevated AFP on amniocentesis may be associated with which condition?

• A. Neural tube defect
• B. Trisomy 18
• C. Trisomy 21
• D. Edwards syndrome

Answer: (A)

Elevated alpha-fetoprotein in amniotic fluid points to an open neural tube defect. AFP is produced by fetal liver and yolk sac and normally present in amniotic fluid in small amounts. If the neural tube doesn’t close properly, AFP leaks into the amniotic fluid and rises, making neural tube defects such as spina bifida or anencephaly the most likely association on amniocentesis. By contrast, the chromosomal abnormalities listed (trisomy 18, trisomy 21, Edwards syndrome) aren’t characteristically linked with high amniotic fluid AFP and are evaluated with other markers and ultrasound findings.