Chorionic Villus Sampling (CVS)

Why this test may be ordered

• To diagnose chromosome problems such as Down syndrome (Trisomy 21), Trisomy 18 (Edward syndrome), or other genetic diseases like cystic fibrosis, sickle cell disease, and Tay-Sachs disease
• If you are age 35 or older and have a higher risk of having a baby with Down syndrome or another genetic disorder
• If you have a family history of a genetic disorder
• If you have had another child with a genetic disorder
• If you had abnormal results on a prenatal screening test

Preparation and collection

On the morning of the test, you may be asked to drink extra fluids and not urinate. This will fill your bladder, which may help move the uterus into a better position for the procedure.

Your provider will use an ultrasound to check your baby's position and guide the procedure. The test usually takes about 30 to 45 minutes. You may have light vaginal spotting after the procedure. A CVS test isn't recommended if you have a sexually transmitted infection (STI) or have had vaginal bleeding during the pregnancy.

CVS is generally considered to be a safe procedure, but it does have some risks. Miscarriage (this is a small risk). Limb defects in the baby (this is very rare). Call your provider if you have chills, contractions, a fever, or amniotic fluid leaking after the procedure.

Understanding results

CVS test results are usually available within two weeks. If you have questions about your results, talk to your provider.

• Normal: If your CVS test results were normal, it is unlikely that your baby has the disorder that was tested. Limitation: But it does not guarantee that your baby won't have any health problems. Next step: If you have questions about your results, talk to your provider.
• Not normal: If your results were not normal, it may mean your baby has a chromosome or genetic disorder, such as Down syndrome or cystic fibrosis. Limitation: Some chromosome and genetic disorders require your baby to have extensive medical treatments. Other disorders may not be treatable. Next step: If your CVS test results were not normal, you should talk with your provider about your options and the decisions you may need to make.
• Unclear: Occasionally, CVS test results are unclear, and your provider may recommend amniocentesis. Limitation: It is performed between the 15th and 20th week of pregnancy. Next step: It may also help to speak to a genetic counselor both before and after you get your results.

• CVS can only diagnose certain genetic diseases and does not diagnose or screen for birth defects such as neural tube defects.
• A normal result does not guarantee that your baby won't have any health problems.
• CVS is not recommended if you have a sexually transmitted infection (STI) or have had vaginal bleeding during the pregnancy.
• There is a small risk of miscarriage, infection, bleeding, Rh sensitization, and very rare limb defects in the baby.

What to do next

If your CVS test results were not normal, you should talk with your provider about your options and the decisions you may need to make. It may also help to speak to a genetic counselor both before and after you get your results.

• What do my CVS test results mean for my baby's health?
• What are my options if the results show a chromosome or genetic disorder?
• Should I speak with a genetic counselor to better understand my results?
• What follow-up tests might be needed if results are unclear?
• How will these results affect my pregnancy care plan?

Evidence source

Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.

U.S. National Library of Medicine: Chorionic Villus Sampling (CVS)

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