Chorionic Villus Sampling

Chorionic Villus Sampling, prenatal test used to detect the presence of genetic disorders in a fetus in the first 10 to 12 weeks of pregnancy. In this procedure, a physician removes cells from a pregnant woman’s chorionic villus, tissue that is part of the developing placenta. This tissue has the same genetic makeup as the fetus, and it can be analyzed in a laboratory to identify any abnormalities.

Physicians use one of two methods to remove chorionic villus cells. In the transcervical method, a physician uses ultrasound to guide a catheter (flexible tube containing a needle) through a woman’s vagina and cervix into the placenta. In the transabdominal method, the physician inserts a needle through the abdominal wall, using ultrasound to guide the needle into the placenta. In both methods, a syringe suctions out cells from the chorionic villus.

This procedure is mostly recommended for couples that have a high risk of conceiving a child with a genetic disorder. Couples considered high risk include those in which the woman is over age 40, those who have already had a child with a genetic disorder, or those in which one parent is a carrier for an inherited disease such as sickle-cell anemia. Chorionic villus sampling provides results earlier than amniocentesis, a prenatal test that cannot be performed until 15 to 17 weeks of pregnancy. See also Birth Defects.