Chorionic Villus Sampling (CVS test)
The test itself is fairly straightforward and takes around twenty minutes to complete. An ultrasound scan is taken to establish where the placenta is lying in your uterus, after which a very fine needle is inserted in your tummy (or occasionally the procedure is carried out through your vagina and cervix) to take out a sample of the placenta.
This sample is taken because the placenta is made up of sections called chorionic villi, which have been formed by the division of the fertilised egg and have exactly the same genetic codes or DNA as the embryo does. This means that any genetic condition (such as Down’s Syndrome) in the embryo will be present in the placenta (but this test will not be able to establish whether your baby has Spina Bifida.
Serum screening
A sample of the pregnant mother’s blood will be taken at this test to measure for three substances, oestriol, human chrorionic gonadotrophin and alpha-fetoprotein. The results are assessed along with the mother’s age to determine the risk of the baby suffering from Down’s syndrome. You will then be offered an amniocentesis test.
You should have the results back from the laboratory within about a week.
If you would like to talk to other mums about chorionic villus sampling, you can visit our chat forum. If you would prefer to ask a question, you can do this on our answers page.
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