CVS testing: Questions About Timing, Results, and Risks

Chorionic villus sampling, usually called CVS, takes a small sample of placental tissue for genetic testing. It may be offered after a screening result, an ultrasound finding or a relevant family history. Before deciding, ask which particular question the test is intended to answer in your pregnancy.

Understand the timing and the sample

CVS is usually performed around 11 to 14 weeks. Ultrasound helps the specialist plan and guide the procedure. The sample is commonly collected using a needle through the abdomen; sometimes it is taken through the cervix instead. The team explains the suitable approach and preparation for you.

The laboratory tests chosen determine which conditions can be assessed. CVS cannot check for every possible health condition. Our screening and diagnostic testing guide explains why a diagnosis answers a more specific question than a screening estimate.

Discuss risks in your own circumstances

CVS carries a small additional risk of miscarriage. For a skilled operator, professional guidance estimates this additional risk is likely below 0.5% for a singleton pregnancy. Twin pregnancies need a separate risk discussion. Ask how your service explains its figures and what they mean alongside the pregnancy’s background risk.

You can also ask about discomfort, infection and the possibility of an unsuccessful sample. Write down the information you most need before consenting rather than feeling that an offered appointment means you have already agreed.

Clarify whether a result is final

An initial result for selected conditions may arrive in about three days, while more detailed testing can take around two weeks. Confirm the expected timing with your clinic.

Occasionally, a chromosome finding in the placenta does not represent the baby’s cells. An uncertain or unexpected result may therefore need further analysis or amniocentesis. Ask the specialist whether the available result is sufficient for a decision, particularly if the scan and laboratory findings do not agree. The amniocentesis guide explains that alternative sample.

Leave with clear aftercare instructions

Arrange the practical support suggested by your clinic and keep its contact details accessible. Get urgent advice after CVS for severe or persistent pain, fever or chills, heavy bleeding, leaking clear fluid or contractions.

Before leaving, confirm who will call, whether there will be more than one result, and what to do if the expected call does not arrive. A short written plan can be easier to use than trying to remember a long conversation on an emotional day.