Chorionic Villus Sampling (CVS)
Reviewed
Chorionic villus sampling (CVS) is a prenatal diagnostic test that checks chorionic villus cells from the placenta for chromosome abnormalities or certain genetic disorders in a developing baby. It is performed between the 10th and 13th week of pregnancy and can almost always tell for sure whether a baby has a chromosome disorder.
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.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- 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, 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. If results are unclear, your provider may recommend amniocentesis.
Evidence source
U.S. National Library of Medicine: Chorionic Villus Sampling (CVS)