Chorionic Villus Sampling (CVS)

Chorionic villus sampling (CVS) is a prenatal test that can detect chromosomal conditions and, when indicated, some genetic diseases. It’s typically performed between 10 and 13 weeks of pregnancy — much earlier than amniocentesis — giving parents an earlier option for diagnostic insight.

CVS uses a small sample of tissue (called chorionic villi) taken from the developing placenta. This tissue contains the same genetic material as the baby, making it a reliable way to test for certain conditions like Down syndrome, Tay-Sachs disease and cystic fibrosis.

However, CVS does not detect neural tube defects such as spina bifida. These can be screened later in pregnancy with a high-resolution ultrasound and a blood test called alpha-fetoprotein (AFP). 

How CVS Is Performed 

The first step is an ultrasound to confirm gestational age and locate the placenta. Depending on its position and the shape of the uterus, your provider may choose one of two CVS methods:

Transabdominal CVS: Similar to amniocentesis, this method involves inserting a thin needle through your abdominal wall, guided by ultrasound, to collect the sample.

Transcervical CVS: A thin, hollow tube is inserted through the cervix and guided by ultrasound to the edge of the placenta, where the sample is taken.

Both procedures usually take only a few minutes. You may feel some discomfort or cramping during or after the procedure. Most women are able to resume their regular activities the next day. 

After the Procedure 

It’s common to experience mild spotting, cramping or bleeding following CVS. These symptoms usually resolve on their own. To help reduce risk and promote healing, follow these guidelines for 72 hours after CVS:

• Avoid air travel
• Avoid sexual intercourse
• Don’t engage in strenuous exercise
• Don’t lift anything heavier than 15 pounds for the first 24 hours

It's important to remember that a small risk of miscarriage exists in any pregnancy, with or without CVS. 

Talk With Your Provider 

CVS can provide valuable information early in pregnancy, but it’s not right for everyone. Your healthcare provider can help you understand your options based on your medical history, age and personal preferences.