How To Say It: kohr-ee-ON-ik vil-uhs sam-puhl-ing trans-suhr-veh-kal
Chorionic villus sampling is a test that is done to look for chromosomal abnormalities in the baby. It is done during the 9th to 13th weeks of pregnancy.
A sample of tissue from the placenta is removed for testing. This is the organ that provides nutrients and oxygen to the baby. It also removes waste from the baby’s blood.
9 Week Old Fetus in Utero
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This test is done to find out if the baby has a chromosomal abnormality, like Down syndrome. It can also look for problems with the genes, such as cystic fibrosis.
This test may be done when:
Problems are rare, but there are some risks with this test. The doctor will go over some problems that could happen, such as:
Things that may raise the risk of problems are:
Your doctor may meet with you to talk about:
The vagina and cervix will be cleansed. A device called a speculum will be inserted to widen the opening of the vagina. An ultrasound will be used to guide a long, thin needle through the vagina to the uterus and placenta. This may cause some cramping. The needle will be used to take a tissue sample from the placenta. The needle will be removed. The sample will be sent to a lab for testing.
30 to 45 minutes
You may have some cramping and spotting right after the test. It should go away in a couple of hours.
The baby's heart rate and vital signs will be monitored. A woman with Rh negative blood will need to receive Rhogam to prevent a health problem called isoimmunization.
Rest will be needed in the first 24 hours before going back to activities. The health team will call with the test results.
Call the doctor if you are not getting better or you have:
If you think you have an emergency, call for medical help right away.
American Congress of Obstetricians and Gynecologists
American Pregnancy Association
Canadian Women's Health Network
The Society of Obstetricians and Gynaecologists of Canada
Chorionic villus sampling (CVS). American Pregnancy Association website. Available at: https://americanpregnancy.org/prenatal-testing/chorionic-villus-sampling/. Accessed July 27, 2020.
Routine prenatal care. EBSCO DynaMed website. Available at: https://www.dynamed.com/management/routine-prenatal-care-36. Updated January 21, 2020. Accessed July 27, 2020.
Sampling of chorionic villus. EBSCO DynaMed website. Available at: https://www.dynamed.com/lab-monograph/sampling-of-chorionic-villus. Accessed July 27, 2020.
Last reviewed March 2020 by
EBSCO Medical Review Board
Elliot M. Levine, MD, FACOG
Last Updated: 3/12/2021