Chorionic Villus Sampling (CVS) is a prenatal test that is useful for detecting certain genetic disorders. The test is used for the same reasons an amniocentesis may be done. The main advantage of CVS is that it can be done much earlier than an amnio. CVS tests can be done as early as the eleventh week of pregnancy.
During the test, a sample of the chorionic villi is taken. The chorionic villi sample can be taken abdominally or vaginally. The sample will be sent out and will grow in a lab before the results are read. You will get the results in about ten days.
The CVS is effective at diagnosing chromosomal abnormalities in the fetus, such as Down’s Syndrome and many others. It is also effective for diagnosing genetic disorders, such as sickle cell anemia or cystic fibrosis. The CVS doesn’t detect neural tube defects such as spina bifida.
The up side of the CVS when compared to the amnio is that the CVS can be done about five weeks sooner. The CVS can be done at eleven weeks. The amnio can’t be done before sixteen weeks. Women who opt for the CVS often don’t want to wait the additional time.
The down side of the CVS is there is a slightly higher risk of miscarriage when compared to the amnio. In extremely rare cases, there have been reports of babies born without fingers or toes. This generally happened when the test was done at nine weeks or sooner.
Because of the increased risk of miscarriage, this test is not offered to all patients. It is usually reserved for couples at an increased risk of certain genetic defects. This is often couples with a strong family history or a previous child born with a birth defect. You may be sent for genetic counseling prior to having the CVS test done.
The precautions after the test are similar to the instructions given after an amnio. You will be instructed to rest for a day or two. You may be told to refrain from intercourse, exercise and other strenuous activity for about three days.
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