Which statement about amniocentesis is true?

Which statement about amniocentesis is true?

• A. It is typically done in the first trimester
• B. It is typically done at 16-18 weeks
• C. It cannot detect chromosomal anomalies
• D. It is performed only if CVS is inconclusive

Answer: (B)

Amniocentesis is timed to balance diagnostic yield with safety, so the mid-second trimester is the standard window. Obtaining amniotic fluid around 16–18 weeks provides enough fetal cells for accurate karyotype analysis and other testing, while keeping risk to the fetus relatively lower than earlier attempts. Performing it in the first trimester is less common due to higher risk and insufficient fetal material for reliable testing. Amniocentesis can detect chromosomal anomalies through analysis of fetal cells, so saying it cannot detect chromosomal abnormalities is incorrect. It isn’t performed only if CVS is inconclusive; it serves as a separate diagnostic option for a variety of indications.

Amniocentesis is timed to balance diagnostic yield with safety, so the mid-second trimester is the standard window. Obtaining amniotic fluid around 16–18 weeks provides enough fetal cells for accurate karyotype analysis and other testing, while keeping risk to the fetus relatively lower than earlier attempts. Performing it in the first trimester is less common due to higher risk and insufficient fetal material for reliable testing. Amniocentesis can detect chromosomal anomalies through analysis of fetal cells, so saying it cannot detect chromosomal abnormalities is incorrect. It isn’t performed only if CVS is inconclusive; it serves as a separate diagnostic option for a variety of indications.