What does it test for?
CVS tests for the same birth defects as amniocentesis, with the exception of neural tube defects. Both amniocentesis and CVS are more than 99 percent accurate in ruling out chromosomal birth defects and specific genetic problems. The benefit of CVS is that the results come back much more quickly than with an amnio. The drawback is that it's slightly more likely to give inconclusive results, which means you may need to get an amnio as well. If you already have a child with a birth defect, had a previous pregnancy affected by a birth defect, or have family members with these disorders and are especially nervous about them, CVS may be something to consider.
When is it done?
It's usually performed between 10 and 12 weeks.
How is it performed?
In CVS, a physician takes a small piece of the chorionic villi, which are wisps of tissue attached to the uterine wall. The cells are collected either by transcervical CVS, in which a thin tube is inserted through your vagina and cervix, or by transabdominal CVS, in which a needle is inserted through your abdomen. The villi have the same biochemical makeup as the fetus and can show the majority of potential birth defects.
As with amniocentesis, some women say that CVS is painless, but others experience cramping when the sample is taken. Rest after the procedure; 1 in 3 women have some bleeding or spotting, which usually stops within a few days. You should always report these symptoms to your healthcare provider. Test results take one to two weeks.
Is it dangerous?
According to the CDC, between one in 100 and one in 200 women miscarry after CVS. So you may want to consider all your options before deciding to have a CVS performed.