Chorionic Villi Sampling is a prenatal test where a small sample of fetal placenta (chorionic villi) is obtained to perform genetic testing. Chorionic Villi sampling is similar to an amniocentesis, but can be performed earlier in a pregnancy. CVS is usually performed between the 8th and 12th week.
CVS: The Procedure
The procedure can be performed either through the cervix or through the abdomen. Doctors will use an ultrasound machine to choose the safest technique. When CVS is performed through the cervix, a small tube will be inserted through the vagina and cervix until the placenta is reached. An ultrasound machine will also be used during the procedure to guide the physician. A small sample of placental is then removed.
When CVS is performed through the abdomen, a needle is inserted into the abdomen, guided by ultrasound imaging, until the placenta is reached. A small amount of placental tissue is then drawn up into a syringe.
CVS: Who should be tested?
- Women who are of advanced age. The risks of having a baby with genetic abnormalities increase with a woman’s age.
- Couples with a family history of genetic defects.
- Couples who have already given birth to a child with genetic defects.
- Women who have displayed other abnormal pre-natal tests.
What can CVS detect?
Chorionic villi sampling detects chromosome abnormalities and genetic disorders. It can also be used to determine paternity. What CVS can not detect is neural tube defects, such as Spina Bifida.
What are CVS risks?
CVS is generally considered a low risk, safe procedure but does come with some risks. Some possible complications include:
- Premature rupture of membranes
What do the results mean?
Lab test result times vary, but on average, CVS results are ready about 10 days post procedure. Most women are provided with definite answers. Sometimes the results show that further testing is required. In this instance, an amniocentesis may be offered.
After the procedure, it’s important to rest and take it easy. Mild cramping and spotting is normal. If you develop a fever, experience excessive vaginal bleeding or discharge, you should call your doctor right away. Your doctor will go over all test results and options with you.
Although CVS is regarded as highly accurate, it can not detect all abnormalities. Even with “normal” CVS results, there is no guarantee your child will be born completely healthy.