What is CVS?

This involves taking a small sample of the placenta, which arises, from the same egg and sperm as the baby. This can be grown on culture media and then analyzed.

When can I have CVS?

A CVS is usually performed at around 12 weeks of pregnancy, but can be done at later gestations.

How is it performed?

Under ultrasound guidance a fine needle is passed through the abdominal wall and into the placenta. The tip of the needle can be seen at all times and never enters the sac containing the baby. Sometimes the placenta is not accessable through the abdomen, by using a speculum the cervix can be seen and a thin catheter passed through the cervix.

 

 

How long does the result take?

The result of the baby's chromosomal makeup is usually available after 9 days. However a new laboratory technique called FISH can give a result on the 5 major chromosomes involved in abnormality, usually within 24 hours.

Is there a risk to my pregnancy?

Yes. There is a background of miscarriage at 12 weeks of pregnancy of around 1.5% and if a CVS is performed there appears to be an additional risk of around 0.25% (ie. 1 in 400). There are no other risks involved in the test. More miscarriages will occur after a CVS than an amniocentesis, but this is due to the background rate of miscarriage and not the procedure.

 

 

 

Information Brochure

Prenatal Diagnosis ~ Special Tests for Your Baby During Pregnancy

Two examinations, Chorionic Villus Sampling and Amniocentesis, are discussed in this brochure. These examinations can identify chromosome abnormalities in the baby that may lead to conditions such as spina bifida and Down syndrome.