A Chorionic Villus Sampling (CVS) is a method to obtain similar genetic information on your baby about a month prior to when an amniocentesis would be offered, usually at 10-13 weeks. The miscarriage rate of CVS and amniocentesis testing is believed to be a hard to estimate.
However, CVS is not widely utilized, partly because of its limited availability, and partly because of the perception that CVS confers increased risks compared with amniocentesis. There are maternal-fetal doctors that specialize just in these tests and perform them everyday so researching a doctor that does just this would be worth the search.
Alternatives to these two invasive procedures (amniocentesis and chorionic villus sampling) include non-invasive(not putting needles into your body) tests, which completely eliminate the risk of miscarriage due to testing. One such test that we recommend starting as early as in the first trimester is a test for copy number abnormalities of chromosomes 13, 18, 21, and the sex chromosomes.
This test uses a simple blood draw from the mother and results are returned in a few days. Currently, many women choose to use a non-invasive method to determine if their baby has a genetic condition; they may only proceed with an amniocentesis or CVS if this preliminary testing is not reassuring.
Although less reliable than the above mentioned test, another non-invasive tests that is commonly done involves a combination of a more thorough ultrasound called a nuchal translucency (NT) and blood tests done in the 1st and 2nd trimesters. See Down’s syndrome testing.
A nuchal translucency ultrasound (commonly called a “nuchal scan” or “NT scan”) is an ultrasound performed between 11.5 and 13 weeks 6 days gestation. It is usually part of an assessment called combined first trimester screening. Combined first trimester screening assesses the risk for your baby having certain chromosomal abnormalities (trisomy 13, 18 and 21).
It simply tells you if your risk is high or low, it does not have the ability to give you 100% answer. This testing combines the nuchal translucency ultrasound with specific blood tests. Nuchal translucency ultrasound alone can also provide this risk assessment, but it is not as accurate as combined first trimester screening.