Chorionic Villus Sampling (CVS)
What is chorionic villus sampling?
Chorionic villus sampling (CVS) is a test that may be done early in pregnancy. The test of a small sample of tissue removed from the placenta can give genetic information about the baby. The test can help you know early in a pregnancy if the baby has a chromosome problem, such as Down syndrome. The test is usually done between the 10th and 13th weeks of pregnancy.
When is it used?
You may consider having CVS because:
- You will be 35 or older on the baby's due date.
- Ultrasound or blood tests suggest the baby may have a problem.
- You or the baby's father may have a family history of problems that can be found with genetic tests.
- You have had a previous pregnancy or child with a birth defect.
- You have had 3 or more miscarriages.
- You have male relatives with genetic diseases, such as hemophilia or muscular dystrophy.
Amniocentesis is another test that can check the baby’s genetic information, but it is done later in pregnancy.
How do I prepare for this test?
If you have a vaginal infection, it should be treated before the test. For this reason, your healthcare provider will check for infection with cultures of the cervix before the test. CVS can be done if the cultures show that you do not have an infection.
What happens during the procedure?
CVS is performed in 1 of 2 ways:
- through the vagina into the cervix (transcervical CVS) or
- through the belly (transabdominal CVS).
For the transcervical test, a thin plastic tube called a catheter is inserted into the vagina and through the cervix to reach the placenta. Ultrasound is used to help guide the tube. The tube is used to get a small sample of placental chorionic villus tissue.
For transabdominal CVS, a needle is inserted through the abdomen and uterus and into the placenta. Ultrasound is used to help guide the needle. The needle and a syringe are used to get a small amount of tissue. This method for getting tissue is similar to amniocentesis. It is used more often than the transcervical test.
What happens after the procedure?
Avoid strenuous activity for 1 to 2 days after the test. You may have a small amount of bloody spotting for up to a week, particularly if the CVS was transcervical.
Genetic specialists will analyze the tissue. You may have some results of the test in 3 to 4 days. You can usually expect the final results within 2 weeks.
What are the benefits of this procedure?
CVS can be done earlier in pregnancy than amniocentesis. With CVS, you can usually have the results of genetic tests before the 14th week of pregnancy. If the test finds a genetic problem, you and your healthcare provider will discuss your options for treatment. The information can help you decide how to manage a pregnancy with a baby that may be affected by a genetic problem.
What are the risks and disadvantages associated with this procedure?
- The biggest risk is miscarriage after the procedure. Miscarriages occur after CVS in about 1 of every 100 procedures. This is slightly higher than the risk with amniocentesis, which is about 1 in 200 procedures.
- Other problems that can occur from CVS are bleeding, cramping, leaking of amniotic fluid, and infection. These problems are very uncommon.
- If CVS is done earlier than the 10th week after your last menstrual period, there may be an increased risk that the baby's jaw and limbs will not grow normally. Ask your healthcare provider about this.
- CVS may be more difficult to do if you are pregnant with more than 1 baby.
- You may not be able to have CVS if your uterus is not in the proper position.
- Sometimes it is not possible to get an accurate result from CVS. In these cases, amniocentesis is usually recommended.
When should I call the healthcare provider?
Call your provider right away if:
- You have a fever over 100°F (37.8°C).
- You have contractions of the uterus or other pain.
- You have heavy bleeding or leaking of fluid from the vagina (more than small amounts of spotting).
Call during office hours if:
- You have questions about the procedure or its result.
- You want to make another appointment.
Developed by Phyllis G. Cooper, RN, MN, and RelayHealth.
Published by RelayHealth.
© 2012 RelayHealth and/or its affiliates. All rights reserved.