Get prediction

CVS (Chorionic Villus Sampling): What It Involves

Chorionic villus sampling, usually called CVS, is a diagnostic test offered in early pregnancy to confirm whether a baby has a chromosomal or genetic condition. It is performed earlier than amniocentesis, which makes it an important option for some women. This guide explains what CVS involves, when it is offered, and how it compares.

Table of Contents

  1. Why CVS Is Offered
  2. What Happens During CVS
  3. Risks and Considerations
  4. CVS vs Amniocentesis
  5. [FAQ](#faq}

Why CVS Is Offered

CVS is offered when screening suggests a higher chance of a chromosomal condition, when an early scan shows a possible concern, when there is a known family history of a genetic condition, or when NIPT has returned a positive result. It can detect Down syndrome, Edwards syndrome, Patau syndrome, and other genetic conditions such as sickle cell disease and cystic fibrosis if tested for. CVS is usually performed between 11 and 14 weeks of pregnancy.

What Happens During CVS

CVS takes around 10 minutes and is guided by ultrasound throughout. The doctor locates your baby and the placenta using the scan. A fine needle is then passed through your abdomen and into the placenta, where a small sample of chorionic villi (tiny finger-like projections) is removed. These cells have the same genetic makeup as your baby. Some centres offer a transcervical approach, where a thin tube is passed through the cervix instead. You may feel some pressure or mild cramping.

Risks and Considerations

CVS carries a miscarriage risk of around 1 to 2%, slightly higher than amniocentesis because it is performed earlier in pregnancy. Other risks include infection, bleeding, and a small chance of an inconclusive result requiring a repeat test. Rarely, the sample contains cells from the placenta that do not match the baby, which may need follow-up. You will receive counselling beforehand to help you decide.

CVS vs Amniocentesis

The main difference is timing. CVS is done between 11 and 14 weeks, while amniocentesis is done after 15 weeks. CVS gives you an answer earlier, which can be important if you are considering your options. However, CVS cannot detect neural tube defects, whereas amniocentesis can measure amniotic fluid proteins that indicate conditions such as spina bifida. Your consultant will help you choose the test that is right for your situation.

FAQ

### Is CVS more painful than amniocentesis?

Most women describe both as uncomfortable rather than painful. CVS may feel a little more crampy because of the location of the placenta, but the procedures are similar in duration and sensation.

How quickly will I get my results?

Preliminary results for common chromosomal conditions are usually available within three to five days. Full results, including detailed genetic tests, can take up to two weeks.

This article is for informational purposes only and does not constitute medical advice.

Further reading:

Related articles: