Chorionic villus sampling
Chorionic villus sampling (CVS) is a prenatal test. It’s used to diagnose certain birth defects and genetic abnormalities in your baby. Genetic abnormalities are changes in the genes that are passed down to a baby from mom or dad. These genetic changes can cause health problems for a baby.
During CVS, your health care provider takes a small piece of tissue from the placenta. The sample is used to check your baby’s health.
You can get CVS early in pregnancy, between 10 and 12 weeks. CVS isn’t given to all pregnant women because there’s a small chance of miscarriage after the test.
CVS is different from another prenatal test called amniocentesis (also called amnio). Amnio is performed a little later in pregnancy. Talk to your provider about having CVS, amnio or other prenatal tests.
Your provider should discuss prenatal testing with you and may offer you CVS. And you can ask to have CVS. You may want to have CVS if you’re at risk for having a baby with a genetic abnormality. These risks include:
- Being 35 or older: The risk of having a baby with certain birth defects or genetic abnormalities, such as Down syndrome, increases as you get older.
- Having a previous child or pregnancy with a birth defect: If you had a child or a pregnancy with a birth defect in the past, your provider should offer you testing.
- Abnormal screening test results: If you had abnormal results from a pregnancy screening test, your provider should discuss CVS with you. CVS can provide specific information to confirm if there is an abnormality in the baby. Most babies with abnormal screening test results don’t have problems and are born healthy.
- Family history of a genetic health problem: If you or your partner has a certain genetic disease (a health condition that gets passed down to a baby from mom or dad), or a close family member with a disease, such as cystic fibrosis or sickle cell anemia, you may want to have CVS.
The test usually takes 30 to 45 minutes.
A health care provider with expertise in performing CVS takes a tiny piece of tissue from the placenta, which has cells from your baby, to check for problems. The placenta grows with your baby in your uterus (womb). It gives your baby food and oxygen through the umbilical cord.
There are two kinds of CVS:
- Testing through the belly (called transabdominal CVS) — Your provider puts a thin needle through your belly into the womb. She then uses the needle to take a small sample of the placenta tissue.
- Testing through the cervix (called transcervical CVS) — Your provider places a thin tube through your vagina and cervix (the opening to the uterus that sits at the top of the vagina). The tube gently sucks in a tiny sample of the placenta tissue.
Your provider sends the tissue sample to a lab where it is examined and tested. Test results are usually ready in about 7 days.
Some women find that CVS is painless. Others feel cramping, similar to period cramps, when the sample is taken. Some women who have testing through the cervix say it feels like having a Pap smear.
After CVS, relax for the rest of the day. You may have spotting or cramping for a few hours after the test. Call your health care provider right away if you have heavy bleeding, fever or contractions.
CVS does involve a small risk of miscarriage. The American College of Obstetricians and Gynecologists (ACOG) reports that 1 in 100 (1 percent) women has a miscarriage following testing.
In most cases, CVS test results show that a baby is healthy and without birth defects. If the test shows that your baby does have a birth defect, talk to your provider about all of your options. Your baby may be able to be treated with medicines or even surgery before birth. Or there may be treatments or surgery he can have after birth.
Knowing about a birth defect before birth may help you get ready emotionally to care for your baby. You also can plan your baby’s birth with your health care provider. This way, your baby can get any special care she needs right after she is born.
Choosing to have CVS is a personal decision. Talking with genetic counselors, your health care provider, and religious and spiritual leaders can help you make decisions about testing for birth defects during pregnancy.
Ask your provider about other prenatal test options and how you can find a doctor who is trained and experienced in offering specific tests. Learn as much as you can about any prenatal tests your provider recommends to make the right decisions for you and your baby.
Last reviewed August 2011
: Your first prenatal checkup, Later prenatal checkups, Birth defects, Amniocentesis, Prenatal tests
Frequently Asked Questions
How is blood pressure measured?
Blood pressure is the force of blood that pushes against the walls of your arteries. Arteries are blood vessels that carry blood away from your heart to other parts of the body. If the pressure in your arteries becomes too high, you have high blood pressure. High blood pressure is also called hypertension.
At each prenantal care visit, your health care provider checks your blood pressure. To do this, she wraps an inflatable cuff around your upper arm. She pumps air into the cuff to measure the pressure in your arteries when the heart contracts (gets tight) and then relaxes.
Your blood pressure reading is given as two numbers: the top (first) number is the pressure when your heart contracts and the bottom (second) number is the pressure when your heart relaxes. A healthy blood pressure is 110/80. High blood pressure happens when the top number is 140 or greater, or when the bottom number is 90 or greater
Your blood pressure can go up or down during the day. Your provider can re-check a high reading to find out if you have high blood pressure during pregnancy.
Last reviewed March 2012
See also: High blood pressure during pregnancy, Preeclampsia, HELLP syndrome
Can a rubella shot hurt my baby during pregnancy?
If you got your rubella shot around the time you got pregnant, it's unlikely that your baby will be harmed by the vaccine. However, it's best to wait to get pregnant for 28 days after vaccination because there is a very small risk of potentially hurting the baby. To date, there hasn't been any birth defects reported that are attributed to the rubella vaccine. In any case, the risk of harming your baby by getting the vaccine at the time you got pregnant is much lower than the risk of harming your baby if you caught rubella during pregnancy.
I couldn't see my baby at my 7 week ultrasound. Why?
At the 7th week of pregnancy, your baby is about ½ an inch long or the size of a blueberry. He's very small. When a transabdominal ultrasound (done on your belly) is done at such an early stage, it's possible that the baby can't be seen. It could be because it's too early in the pregnancy or because you conceived a little later than what you thought. Your health care provider might recommend a transvaginal ultrasound (done inside the vagina) to help see the baby more clearly.
What are choroid plexus cysts?
The choroid plexus is the area of the brain that produces the fluid that surrounds the brain and spinal cord. This is not an area of the brain that involves learning or thinking. Occasionally, one or more cysts can form in the choroid plexus. These cysts are made of blood vessels and tissue. They do not cause intellectual disabilities or learning problems. Using ultrasound, a health care provider can see these cysts in about 1 in 120 pregnancies at 15 to 20 weeks gestation. Most disappear during pregnancy or within several months after birth and are no risk to the baby. They aren't a problem by themselves. But if screening tests show other signs of risk, they may indicate a possible genetic defect. In this case, testing with higher-level ultrasound and/or amniocentesis may be recommended to confirm or rule out serious problems.