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Chorionic villus sampling (CVS) is a test done during pregnancy. It looks for certain genetic problems with your baby (fetus). The same genes that are in your baby are in the placenta. The placenta is a large organ that forms in your uterus when you are pregnant. It supplies your baby with nutrients and oxygen through the umbilical cord. A small piece of the placenta is taken out and tested.
This test is usually done when you are 10 to 13 weeks pregnant but it can be done later in your pregnancy if needed.
CVS can find genetic conditions, such as Tay-Sachs disease or hemophilia. It can also find chromosomal abnormalities, such as Down syndrome (Trisomy 21), Trisomy 13, and Trisomy 18.
You may want to have this test because:
You may want to talk to a genetic counsellor before or after the test. This person is trained to give you detailed information about the test. They can help you make decisions about testing. The counsellor can also help you understand the results of the tests.
You may be asked to drink a glass of fluid about an hour before the test so that your bladder is moderately full. A moderately full bladder makes it easier to do the test.
You will be asked to sign a consent form that says you understand the risks of the test and agree to have it done.
There are two ways to do this test. One way is through the belly (transabdominal). The other way is through the cervix (transcervical).
You may feel a short, sharp sting from the needle used to give the numbing medicine. There is usually no pain when the collecting needle is put in the belly. You may have some cramping when the needle is in your uterus.
Most women do not find this procedure painful. You may feel some pressure or mild discomfort when the speculum is placed in your vagina. You may have some cramping when the catheter is put through your cervix.
The test will take about 30 minutes. Getting the sample takes only a few minutes.
Call your doctor, midwife, or nurse advice line now or seek immediate medical care if:
Watch closely for changes in your health, and be sure to contact your doctor, midwife, or nurse advice line if you have any problems.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.
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Adaptation Date: 2/24/2022
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
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