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Chorionic Villus Sampling (CVS) is a procedure done early in pregnancy to look for certain genetic abnormalities in a developing fetus. This test is offered to women who are at high-risk for fetal genetic abnormalities because of their:

  • Age
  • Family history
  • Abnormal screening test

Women usually undergo genetic counseling before having CVS.

This procedure is usually performed in the first trimester (between approximately 10-1/2 weeks to 14 weeks gestation). CVS can be performed in two different ways:

  • Transcervically (through the cervix) using a flexible catheter
  • Transabdominally (through the maternal abdomen) using a thin needle

Both techniques use continuous ultrasound guidance. The catheter or needle is placed within the placenta (afterbirth) where the sample of chorionic villi is obtained which can then be sent for genetic testing.

Frequently Asked Questions

What are the risks to my baby?
Any diagnostic procedure carries some risk. Your physicians and the genetic counselors at the Prenatal Diagnosis and Treatment Center at Johns Hopkins will explain the test and risks so you can make an informed decision about whether to proceed.

Will I need to have a full bladder?
Yes, a full bladder makes it easier to do the test, so your doctor may recommend drinking a full glass or two of water about an hour before the test.

When will I get the results?
10 – 14 days, in most cases.


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