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    Chorionic Villus Sampling (CVS)

    Why It Is Done

    Chorionic villus sampling may be done during your first trimester of pregnancy to find certain birth defects.

    You may choose to have this test because:

    • Of your age. As you get older, you have a greater chance of having a baby with a birth defect. Many doctors use 35 and older as the age for higher risk.
    • You want to know for sure if your baby has a certain health problem. This may help you decide early whether you want to continue your pregnancy or make plans to care for a sick child.
    • You or the baby's father carries an abnormal gene that is known to cause a disease, such as Tay-Sachs disease, sickle cell anemia, or cystic fibrosis.
    • You or the baby's father has a family history of a genetic disorder or birth defect.
    • Screening tests suggest that your chance of having a baby with a genetic disorder or birth defect is higher than average.

    How To Prepare

    You may be asked to drink a glass of fluid about an hour before the test so that your bladder is full. A 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.

    Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

    Be sure to tell your doctor if you are allergic to any medicines, such as numbing medicines (local anesthetics), before the procedure.

    How It Is Done

    Chorionic villus sampling is most commonly done by a perinatologist in the doctor's office or the hospital. An overnight stay in the hospital usually is not needed unless problems occur during the procedure.

    Transabdominal (through the belly) chorionic villus sampling or transcervical (through the cervix camera.gif) chorionic villus sampling can be done. The choice may depend on where the fetus and placenta are in the uterus.

    Through the belly (transabdominal)

    WebMD Medical Reference from Healthwise

    Last Updated: June 04, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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