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School of Medicine
Chorionic Villus Sampling (CVS)
Chorionic villus sampling (CVS) is a procedure done early in pregnancy to test for certain genetic abnormalities in a developing fetus. Women usually undergo genetic counseling before having CVS.
- Learn more about CVS in the Johns Hopkins Health Library.
- Learn more about common tests during pregnancy in the Johns Hopkins Health Library.
Frequently Asked Questions
Why is CVS performed?
Your doctor may recommend CVS because of advanced maternal age (e.g., 35 or older), your family history, or because other prenatal screenings may have revealed a risk that the baby may have an inherited or congenital condition.
What are the risks to my baby?
Any diagnostic procedure carries some risk. Your physicians and the genetic counselors at the Prenatal Diagnosis and Treatment Center at Johns Hopkins will explain the procedure and risks so you can make an informed decision about whether to proceed.
Who will perform CVS?
A maternal-fetal medicine provider will perform the CVS, along with a sonographer.
When will the procedure be done?
This procedure is usually performed in the first trimester (between approximately 10.5 to 14 weeks gestation) but may also be performed later in pregnancy in certain circumstances.
What can I expect during CVS?
CVS can be performed in two ways: transcervically (through the cervix), using a flexible catheter, or transabdominally (through the maternal abdomen), using a thin needle. Both techniques use continuous ultrasound guidance. The catheter or needle is placed within the placenta (afterbirth) where the sample of chorionic villi is obtained, which can then be sent for genetic testing.
Will I need to have a full bladder?
Yes, a full bladder makes it easier to do the procedure, so your doctor may recommend drinking a full glass or two of water about an hour before CVS.
Where will the procedure be performed?
Prior to CVS, you may have an ultrasound performed in one of our ultrasound suites. The CVS will then be performed in the same room.
What can I expect after CVS?
You may have some spotting or brown discharge for up to a week following CVS. If you do experience spotting, use sanitary napkins (not tampons). Do not have sexual intercourse, soak in bath water or go swimming until your spotting has completely stopped. Some women experience mild cramping similar to menstrual cramps. Cramping usually subsides after a few hours.
When will I get the results?
You will get the results in 10 to 14 days, in most cases, but it depends on what tests you are having.