Ohio State’s Maternal Fetal Medicine team has been performing CVS since 1989. CVS is a diagnostic procedure that can identify or rule out certain chromosome conditions such as Down syndrome. CVS may also be used to diagnose certain genetic conditions like Tay-Sachs disease or cystic fibrosis. It is typically performed between 10–12 weeks of pregnancy. With CVS, doctors collect a small amount of tissue from the developing placenta (called chorionic villi). The cells from this tissue are sent to a special laboratory for testing.
A sample of chorionic villi is obtained by inserting a needle through the mother’s abdomen into the placenta, or by inserting a thin, hollow tube (called a catheter) through the mother’s cervix into the placenta. With either method, an ultrasound is used to guide the procedure. A specially trained doctor performs the procedure. With chorionic villus sampling, there is a small risk of miscarriage, approximately 1 in 100 (or 1 percent). The risk of miscarriage is the same whether the doctor goes through the women’s abdomen or her cervix. This risk is lowest when an experienced physician performs the CVS. Most patients feel a bit of pressure or mild discomfort during the procedure, but almost all patients report that the procedure was much easier than they had imagined.
Rarely (1–2 percent of the time), a sample can not be interpreted. This may be due to poor growth of the cells once in the laboratory, to placental mosaicism (when the cells from the placenta differ from the baby), or to contamination of the sample by maternal cells. If a result is unclear, an amniocentesis may be offered. Results from this testing are available approximately 10–14 days after the initial procedure. Since CVS does not test for open neural tube defects (such as spina bifida and anencephaly) it is often recommended that women also pursue second trimester alpha-fetoprotein (AFP) screening and/or a detailed ultrasound.
Chorionic Villus Sampling Fact Sheet PDF