Chorionic Villi Sampling
What Is Chorionic Villi Sampling (CVS)?
CVS is a procedure used to detect birth defects by taking a sample of cells from parts of the placenta called the chorionic villi, which have the same genes as the fetus. CVS can detect most of the same defects as amniocentesis, but it cannot detect open neural tube defects. If you have CVS, you may want to consider having a blood alpha-fetoprotein (AFP) test later in your pregnancy to test for neural tube defects.
Who Should Have CVS?
Your healthcare provider will make recommendations for testing based on your genetic risk. Either amniocentesis or CVS should be recommended if:
- You will be 35 years old or older when you give birth.
- You have a family history of certain birth defects.
- You already had a child with a birth defect.
- You have abnormal results on other genetic tests.
How Is the Procedure Performed?
CVS is usually done about 10-12 weeks from a woman's last menstrual period. The procedure is performed in the healthcare provider's office or hospital. Cells can be collected from the placenta in two ways—through the abdomen, or through the vagina. If you have any bleeding during pregnancy, problems with your cervix, or a sexually transmitted disease, you may be offered CVS through the abdomen as the preferred route.
If collecting cells through the abdomen, the clinician will carefully insert a needle through your abdomen to your placenta. A sample of chorionic villi will be collected. If collecting cells through the vagina, the clinician will insert a speculum. A thin tube will then be inserted into your vagina and up through your cervix. An ultrasound will be used to guide the tube to your placenta and a small sample of chorionic villi will be removed and sent to a lab. Results may take about 10 days.
Are There Any Risks Associated With CVS?
There is a risk of infection with CVS. Because the procedure is done earlier than amniocentesis, there is a slighly higher risk of miscarriage. In rare cases, limb deformities have occurred in infants, especially when CVS was done before 10 weeks.
American College of Obstetricians and Gynecologists
International Childbirth Education Association
Last reviewed July 2007 by Ganson Purcell Jr., MD, FACOG, FACPE
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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