Pregnancy and Chorionic Villus Sampling
Who Should Be Tested With CVS?
According to the American College of Obstetrics and Gynecology, CVS testing should be offered to:
- Pregnant women who will be 35 or older on their due date (the risk of having a baby with a chromosomal problem such as Down syndrome increases with the age of the woman)
- Couples who already have had a child with a birth defect or have a family history of certain birth defects
- Pregnant women with other abnormal genetic test results
Your health care provider can advise you on whether this test is right for you. In the end, only you and your partner can decide whether or not you should have this test.
How Is the CVS Test Performed?
Before undergoing a CVS prenatal test, appropriate genetic counseling, including a detailed discussion regarding the risks and benefits of the procedure, are recommended.
At the time of initial consultation and counseling, an ultrasound exam will be performed to confirm gestational age (the development stage of the embryo) and the location of the placenta. This is done so that CVS can be performed at the appropriate gestational age (which is usually 10 to 12 weeks from the woman's last menstrual period).
There are two ways to collect chorionic villi from the placenta: through the vagina or through the abdomen.
To collect cells through the vagina, a speculum is inserted (in the same way as a Pap test). Then a very thin, plastic tube is inserted up the vagina and into the cervix. Using ultrasound images, the tube is guided up to the placenta, where a small sample is removed.
To collect cells through the abdomen, a slender needle is inserted through the woman's abdomen to the placenta, much like in amniocentesis.
The sample of chorionic villi is then sent to a lab, where the cells are grown in a special fluid and tested a few days later. Culture results will be available within two weeks. Your doctor will notify you of the results.
Will the CVS Test Be Painful?
It could be, but it's over relatively quickly. The test takes no longer than a half hour from start to finish. The extraction itself runs only a few minutes.