Chorionic Villus Sampling (CVS)

Chorionic villus sampling (CVS) is a test that can be done early in a woman’s pregnancy to determine if the fetus has certain conditions. CVS can tell whether a baby has Down syndrome, cystic fibrosis or other genetic or chromosomal conditions. DNA from a CVS test can also be used as part of a paternity test. CVS can usually be performed between 10 and 13 weeks gestation — much earlier than other tests.

During CVS, a small sample of tissue is removed from the placenta for testing. The procedure can be performed in two ways — transabdominally (through the abdomen) or transcervically (through the cervix) — depending on where the placenta is located. Both methods of CVS are performed with ultrasound guidance.

Good candidates for CVS include women who:

  • Will be 35 years of age or older at the time of delivery
  • Had an abnormal first trimester screening result
  • Have a family history of a genetic condition such as cystic fibrosis or sickle cell anemia
  • Have had a prior birth involving a genetic condition
  • Had an abnormal finding on an ultrasound

While most CVS tests are performed through the abdomen, about 5 percent to 10 percent need to be performed transcervically (through the cervix) because of the placenta’s location. It takes much more training and experience to conduct a CVS test transcervically.

Frequently Asked Questions

What is chorionic villus sampling?

Who should undergo CVS?

What is the chorion?

What does a test of the chorion tell me about the health of the fetus?

What tests are usually included in the genetic testing of CVS tissue?

What will I need to do prior to the procedure?

How is CVS performed?

Which CVS approach will I have?

Are transabdominal and transcervical CVS equally safe?

What are my alternatives to CVS?

How long does CVS take and what does it feel like?

What are the advantages of CVS?

What are the risks of CVS?

What can I expect after a CVS?


Medical College of Wisconsin,
Department of Obstetrics & Gynecology
9200 West Wisconsin Ave.,
Milwaukee, WI 53226-3522
Phone: (414) 805-6600
24-Hour Emergency Line: (414) 805-6700

Children's Hospital of Wisconsin

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