Chorionic villus sampling (CVS)

Chorionic villus sampling (CVS) is a test that determines birth defects in an unborn baby. It is usually offered to women who have a risk of having a baby with a birth defect.

The procedure consists of inserting a small thin plastic tube or needle through either the vagina into the cervix, or through the abdomen and into the placenta. A small sample of tissue is removed from the placenta for testing. The results are usually available within 5 days following the procedure.

Among the complications resulting from the CVS include miscarriage occurring in about 1 of every 100 procedures. Other problems that can occur are bleeding, cramping, leaking of amniotic fluid, and infection, but this is rare and happens in 1 percent or less of the women tested.

Your healthcare provider may suggest you have a CVS for the following reasons:

• over age 35
• a previous pregnancy or child with a birth defect
• a family history of retardation, Down syndrome, or other inherited disease (such as Tay-Sachs, sickle cell anemia, or cystic fibrosis)
• a history of 3 or more miscarriages or
• any male relatives with hemophilia or muscular dystrophy

Your provider may suggest an alternative procedure, an amniocentesis rather than a CVS, if you have had a previous pregnancy or child with spinal or brain defect as these cannot be diagnosed with CVS.

CVS can be done early in the pregnancy, 10 to 12 weeks after a woman has missed her period. If an untreatable birth defect is discovered, there is time to decide whether or not to continue the pregnancy, or if you decide to continue the pregnancy, more time to prepare for the baby's problems.

Some birth defects can be treated once diagnosed. For this reason, it is important for a woman to have care early in her pregnancy and when possible see her provider before becoming pregnant.

Last Reviewed 2005

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

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