What is Chorionic Villus Sampling (CVS)?

The journey of pregnancy is often filled with joy and anticipation, but for some expectant parents, it can also bring difficult decisions and unexpected challenges. One such challenge is deciding whether to undergo Chorionic Villus Sampling (CVS). Chorionic villus sampling (CVS) is a type of prenatal diagnostic test performed between 10 and 13 weeks of pregnancy. This test can tell if a baby has certain (not all) genetic conditions or chromosome conditions. CVS can be performed earlier in pregnancy than amniocentesis. The results can provide more accurate information than screening tests (performed on a pregnant person’s blood), and may allow for earlier decision-making and potential interventions compared to other genetic tests.

CVS is performed in one of two ways (listed below), depending on the where the placenta is located in the uterus. An ultrasound is performed before a CVS to determine the position of the placenta and which way to perform the procedure.

1. Transcervical: A thin tube (catheter) is inserted through the cervix into the placenta to collect the tissue sample.
2. Transabdominal: A long, thin needle is inserted through the abdomen and uterus into the placenta to collect the tissue sample.

Both methods use ultrasound to help collect a small sample of chorionic villi cells from the placenta. These cells typically contain the same genetic make-up as the baby. The procedure usually takes a few minutes and may cause some discomfort or cramping. In some cases, the abdomen may be numbed prior to the procedure.

Potential risks of CVS include:

• Miscarriage: The risk is approximately 1 in 450 (less than 1% chance), which is slightly higher than the risk associated with amniocentesis (which is 1 in 900).
• Infection: Though rare, there is a small risk of introducing infection during the procedure.

You might consider CVS for several reasons:

• A desire for comprehensive information about chromosome conditions
• Advanced maternal or paternal age
• Abnormal prenatal screening results (this could be one of many different blood tests performed on pregnant person, such as first trimester screening or noninvasive prenatal testing/NIPT)
• Family history of, or prior pregnancy affected with a genetic or chromosome condition

Many different genetic tests can be performed on the sample collected. A genetic counselor or other genetics healthcare provider can help you determine which tests are right for you, based on your family history and other factors. Unlike amniocentesis, CVS cannot detect neural tube defects like spina bifida.

It’s important to remember that there’s no universally “right” choice when it comes to CVS. What matters most is making an informed decision that aligns with your values, beliefs, and circumstances. Watch this video to learn if prenatal genetic testing may be right for you.