Chorionic villus sampling (CVS) is a prenatal test used to detect genetic abnormalities in a developing fetus. It involves taking a small sample of tissue from the placenta, which contains cells that are genetically identical to the fetus. This procedure is typically performed between the 10th and 13th weeks of pregnancy and can provide early information about conditions such as Down syndrome and other chromosomal disorders. The sample is collected either through the cervix (transcervical) or through the abdominal wall (transabdominal) using a thin needle. Results from CVS can help expectant parents make informed decisions about their pregnancy. However, like any medical procedure, it carries some risks, including a small chance of miscarriage.