Which prenatal diagnostic procedure involves extraction of a tiny amount of fetal tissue at 9-11 weeks to test for chromosome 21 (Down syndrome)?

Which prenatal diagnostic procedure involves extraction of a tiny amount of fetal tissue at 9-11 weeks to test for chromosome 21 (Down syndrome)?

• A. Chorionic Villus Sampling
• B. Amniocentesis
• C. Percutaneous Umbilical Blood Sampling (PUBS)
• D. Cordocentesis

Answer: (A)

Chorionic villus sampling allows you to obtain fetal tissue from the placenta around 9–11 weeks, giving immediate access to fetal chromosomes for testing such as chromosomal abnormalities like trisomy 21 (Down syndrome). This early tissue sample enables karyotyping or rapid genetic assays, which is why it fits the scenario described. Amniocentesis uses amniotic fluid and is typically performed later (about 15–20 weeks). Percutaneous umbilical blood sampling and cordocentesis involve fetal blood from the umbilical cord and are also done later in pregnancy.

Chorionic villus sampling allows you to obtain fetal tissue from the placenta around 9–11 weeks, giving immediate access to fetal chromosomes for testing such as chromosomal abnormalities like trisomy 21 (Down syndrome). This early tissue sample enables karyotyping or rapid genetic assays, which is why it fits the scenario described. Amniocentesis uses amniotic fluid and is typically performed later (about 15–20 weeks). Percutaneous umbilical blood sampling and cordocentesis involve fetal blood from the umbilical cord and are also done later in pregnancy.