Chorionic Villus Sampling

What is chorionic villus sampling (CVS)?

Chorionic villus sampling (CVS) is a test done early in a woman’s pregnancy. CVS checks for genetic problems in your baby. During CVS, your health care provider takes a small piece of tissue from the placenta for testing. This tissue has the same genetic material as your baby. It can show if your baby is developing problems as it grows.

Women who have a higher risk or a family history of genetic problems may want to consider CVS testing.

How is chorionic villus sampling performed?

CVS is usually done between the 10th and 12th weeks of pregnancy. The test can be done through your belly (transabdominal) or your cervix (trabscervical). It is common to feel some cramping during and after the CVS procedure.

Transcervical CVS:

  • A small tube called a catheter is moved through the vagina and cervix to the uterus

  • Ultrasound is used to guide the catheter into place near the placenta.

  • Tissue is taken using a tiny syringe at the end of the catheter.

Transabdominal CVS

  • A needle is inserted through the belly (abdomen) and into the uterus.

  • Ultrasound is used to guide the needle into place near the placenta

  • A small amount of tissue is taken into the syringe.

The tissue samples are sent to a laboratory to be checked. Test results are usually ready in about 10 to 14 days.

Women with more than one baby may need to have tissue taken from each placenta. However, CVS is not always successful in women with more than one baby. This is because the position of the babies in the uterus can make it difficult to get a tissue sample.

Some women may not be able to have CVS. The results of your CVS test may not be 100 percent accurate. In this case, you may need a follow-up test called an amniocentesis. You may not be able to have CVS if you have a vaginal infection such as herpes or gonorrhea. It is also possible that your health care provider won’t be able to get big enough a sample to grow in the laboratory.

What are the risks and benefits of chorionic villus sampling?

The risks of CVS are:

  • Miscarriage

  • Infection

  • Rh incompatibility in the mother.

The benefits of CVS include early diagnosis of genetic conditions, such as:

  • Down syndrome

  • Tay-Sachs disease

  • Cystic fibrosis

  • Sickle cell anemia

Talk about the risks and benefits of CVS with your health care provider.