When is chorionic villus sampling usually performed?

Chorionic villus sampling (CVS) is typically performed during the first trimester of pregnancy, usually between 10 and 13 weeks gestation. This timing is significant because it allows for early detection of genetic disorders and chromosomal abnormalities, which can be crucial for decision-making regarding the pregnancy. CVS involves obtaining a small sample of the placental tissue (chorionic villi) for testing. The procedure can be done either through the cervix (transcervical) or through the abdomen (transabdominal), depending on the specific circumstances and the healthcare provider's preference.

Performing CVS during the first trimester has benefits, including potentially allowing for earlier intervention or preparation should any genetic issues arise. It contrasts with other procedures, such as amniocentesis, which is generally done later in pregnancy, typically in the second trimester, and poses a different risk profile and window for diagnosis.