Definition
A procedure that involves taking a small sample of cells called chorionic villi from the placenta. DNA can be extracted from this sample to test for certain conditions.
Use in clinical context
Some genetic diagnoses can be made by testing an unborn baby during pregnancy. Examples include Down syndrome, sickle cell disease and Duchenne muscular dystrophy. Chorionic villus sampling is one way that DNA can be obtained to test for these conditions.
The cells taken during chorionic villus sampling are from the placenta. This usually has the same genome as the fetus, except in some cases where a variant may have arisen in one but not the other. This procedure carries a risk of miscarriage and the information about this should be communicated to the parents. The decision to undergo the procedure is always an individual one and many factors are usually considered by the parents before making the decision to undergo the procedure or not.
