Chorion Villus Sampling (CVS)

A CVS involves passing a fine needle into the frond like tissue on the outside of the pregnancy sac. This is the tissue that eventually develops into the placenta.

Because the villi also develop from the fertilized egg, analysis of this tissue will give the same result as if the fetus itself were examined.

The procedure is done under continuous ultrasound vision in order to keep any threat to your developing baby to an absolute minimum.

A tiny sample is aspirated and we send it to the laboratory for analysis. A local anesthetic ensures that the procedure carries little discomfort. The test only takes one or two minutes.

Sometimes we choose to do the test through the vagina (similar to having a smear test) if it is considered safer for your baby. Being able to offer both methods gives us the best chance of keeping risk to a minimum.

A small risk of miscarriage (1%) is associated with the test and, because the test is done early in the pregnancy at 12-14 weeks, the background risk may still be higher than when an amniocentesis is performed later in pregnancy.

Most commonly the test is done to exclude Down Syndrome in which case the result is available in 2 days. The full analysis of other chromosomal problems can take up to 2 weeks.

Most laboratory testing gives a straightforward answer. However, in about 1% of cases, there may need to be further discussion or testing should the results not be clear-cut.

For bookings information and prices please see our Appointments page.