When you’re expecting a baby, your healthcare provider may offer various prenatal tests to check your baby’s health. One such test is Chorionic Villus Sampling (CVS), which can provide important information about your baby’s genetic makeup. While CVS isn’t a routine test, it can be a valuable tool for expectant parents facing higher risks of genetic conditions. Here’s what you need to know about CVS, including how it’s done, what it detects, and when you might consider it.
What Is Chorionic Villus Sampling (CVS)?
CVS is a prenatal test that involves taking a small sample of cells from the placenta, called chorionic villi, to check for chromosomal abnormalities and genetic disorders. The placenta shares the baby’s genetic material, making it possible to diagnose conditions early in pregnancy.What Does CVS Test For?
CVS primarily screens for:- Chromosomal abnormalities, such as Down syndrome (trisomy 21) or trisomy 18
- Genetic disorders, like cystic fibrosis, Tay-Sachs disease, and sickle cell anemia
- Other inherited conditions if there’s a family history
When Is CVS Done?
CVS is typically performed between 10 and 13 weeks of pregnancy, making it an earlier alternative to amniocentesis, which is done later in the second trimester. This earlier testing allows parents to make more timely decisions about their pregnancy if necessary.Who Should Consider CVS?
Your healthcare provider may recommend CVS if:- You have a family history of genetic disorders
- Previous pregnancies were affected by genetic conditions
- You’re 35 or older, which increases the risk of chromosomal abnormalities
- Abnormal results were found during non-invasive prenatal testing (NIPT) or first-trimester screening
How Is CVS Performed?
There are two methods for performing CVS, depending on the location of the placenta:1. Transcervical Method
- A thin tube is inserted through the cervix to reach the placenta.
- Ultrasound guidance is used to ensure accuracy.
- A small sample of chorionic villi is gently suctioned out.
2. Transabdominal Method
- A thin needle is inserted through the abdomen into the placenta.
- The procedure is similar to an amniocentesis, with ultrasound guidance for precision.
Risks and Considerations
While CVS is considered safe, it is an invasive procedure, so there are some risks, including:- Miscarriage: The risk is estimated to be around 0.22% to 0.9%, slightly higher than amniocentesis.
- Infection: Though rare, there’s a small chance of infection.
- Cramping or spotting: Mild cramping and light spotting may occur after the procedure but usually resolve quickly.
After the Procedure: What to Expect
Most women experience mild discomfort, similar to menstrual cramps, following CVS. It’s normal to have light spotting for a day or two. However, contact your doctor if you experience:- Heavy bleeding
- Severe cramping
- Fever or chills
Final Thoughts
Chorionic villus sampling is a powerful diagnostic tool that can provide early and detailed information about your baby’s health. While the decision to undergo CVS is personal, understanding the procedure and its benefits can help you make an informed choice. If you’re considering CVS, speak with your healthcare provider about whether it’s right for you, and rest assured that you’ll be supported every step of the way.

Content Reviewed by Dr V.
Learn MoreDr. Vaheh Shirvanian, a family medicine physician and father. With over 17 years of experience, he specializes in inpatient acute hospital care, outpatient family medicine, urgent care, emergency medicine, and hospice care. Dr. V is passionate about guiding new parents through the challenges and joys of parenthood, offering compassionate and expert support at every step.