Amniocentesis, chorionic villus sampling (CVS) and alpha‑fetoprotein (AFP) testing are used to detect fetal chromosomal abnormalities (e.g., Down, Edwards, Patau), many inherited genetic disorders, and certain infections. AFP (maternal serum or amniotic) screens for neural tube defects (spina bifida, anencephaly) and abdominal wall defects. CVS and amniocentesis provide definitive genetic diagnosis; AFP is a screening tool.

The alpha‑fetoprotein (AFP) test measures AFP — a fetal protein — in maternal blood during the second trimester (commonly 15–20 weeks). It’s a screening tool for neural tube and abdominal wall defects and helps assess aneuploidy risk when combined with other markers. Abnormal AFP levels don’t diagnose a condition but prompt further evaluation, such as detailed ultrasound or amniocentesis.

Amniocentesis and chorionic villus sampling (CVS) are prenatal diagnostic tests that detect chromosomal and genetic conditions. CVS samples placental tissue earlier (about 10–13 weeks), while amniocentesis samples amniotic fluid later (about 15–20 weeks). Both give definitive genetic information but carry a small risk of miscarriage and infection; timing, risks, and alternatives should be discussed with a specialist.

A prenatal test in pregnancy assesses the developing baby’s health and risk of conditions before birth. Tests include screening (blood tests, ultrasounds, noninvasive prenatal testing) and diagnostic procedures (chorionic villus sampling, amniocentesis) to detect chromosomal abnormalities, genetic disorders, neural-tube defects and infections. Results help guide clinical care, inform decisions, and plan monitoring or treatment during pregnancy and after delivery.

Amniocentesis is a diagnostic prenatal test that collects amniotic fluid to detect chromosomal abnormalities such as Down syndrome, genetic disorders, neural tube defects, and certain infections. It can assess fetal lung maturity and Rh status when needed. Typically performed from about 15 to 20 weeks’ gestation, results help confirm diagnoses, guide pregnancy management, and inform parental decision making, though the procedure carries a small risk of miscarriage.

If a CVS result is positive for a genetic or chromosomal condition, your provider will arrange counseling to explain the finding, its certainty, and implications. Because CVS samples placental tissue, confirmatory testing (usually amniocentesis) may be offered to exclude confined placental mosaicism. You’ll discuss prognosis, specialist referrals, pregnancy management options, and emotional support, including preparation for care after birth or consideration of termination where legally available.