Chorionic Villus Sampling (CVS)

Chorionic Villus Sampling (CVS)

(CVS, Chorionic Villus Biopsy)

Procedure Overview

What is chorionic villus sampling?

Chorionic villus sampling (CVS) is a prenatal test that involves taking a sample of tissue from the placenta, a structure in the uterus that provides blood and nutrients from the mother to the fetus, to test for chromosomal abnormalities and certain other genetic problems.

The chorionic villi are tiny projections of placental tissue that look like fingers and contain the same genetic material as the fetus. Testing may be available for other genetic defects and disorders depending on the family history and availability of lab testing at the time of the procedure.

CVS is usually performed between the 10th and 12th weeks of pregnancy. Unlike amniocentesis (another type of prenatal test), CVS does not provide information on neural tube defects, such as spina bifida. For this reason, women who undergo CVS also need a follow-up blood test between 16 to 18 weeks of their pregnancy to screen for neural tube defects.

There are two types of CVS procedures:

Another related procedure that may be used to diagnose genetic and chromosomal defects is amniocentesis. Please see this procedure for additional information.

Anatomy of the fetus in utero:

Illustration of fetus in utero
Click Image to Enlarge

Reasons for the Procedure

Chorionic villus sampling may be used for genetic and chromosome testing in the first trimester of pregnancy in the presence of one or more of the following conditions:

There may be other reasons for your physician to recommend a chorionic villus sampling.

Risks of the Procedure

As with any invasive procedure, complications may occur. Some possible complications may include, but are not limited to, the following:

Patients who are allergic to or sensitive to medications or latex should notify their physician.

Women with twins or other multiples will need sampling from each placenta in order to study each baby.

There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.

Certain factors or conditions may interfere with CVS. These factors include, but are not limited to, the following:

Before the Procedure

During the Procedure

Illustration demonstrating a transcervical chorionic villus sampling
Click Image to Enlarge

A CVS procedure may be performed on an outpatient basis, or as part of your stay in a hospital. Procedures may vary depending on your condition and your physician’s practices.

Generally, a CVS procedure follows this process:

  1. You will be asked to undress completely, or from the waist down, and put on a hospital gown.
  2. You will be asked to lie down on an examination table and place your hands behind your head.
  3. Your vital signs (blood pressure, heart rate, and breathing rate) will be checked.
  4. An ultrasound will be performed to check the fetal heart rate, and the position of the placenta, fetus, and umbilical cord.
  5. Based on the location of the placenta, the CVS procedure will be performed through your cervix (transcervical) or through your abdominal wall (transabdominal).

For a transcervical CVS procedure:

  1. The physician will insert an instrument called a speculum into your vagina to spread the walls of the vagina apart.
  2. Your vagina and cervix will be cleansed with an antiseptic solution.
  3. Using ultrasound, a thin tube will be guided through the cervix to the chorionic villi.
  4. Cells will be gently suctioned through the tube into a syringe. You may feel a twinge or slight cramping. More than one sample may be needed to obtain enough tissue for testing.
  5. The tube will then be removed.

For a transabdominal CVS procedure:

  1. For an abdominal CVS, your abdomen will be cleansed with an antiseptic. You will be instructed not to touch the sterile area on your abdomen during the procedure.
  2. The physician may inject a local anesthetic to numb the skin. If a local anesthetic is used, you will feel a needle stick when the anesthetic is injected. This may cause a brief stinging sensation.
  3. Ultrasound will be used to help guide a long, thin, hollow needle through your abdomen and into the uterus and placenta. This may be slightly painful, and you may feel a cramp as the needle enters the uterus.
  4. Cells will be gently suctioned into a syringe. More than one sample may be needed to obtain enough tissue for testing.
  5. The needle will then be removed. An adhesive bandage will be placed over the abdominal needle insertion site.

Procedure completion, both methods:

  1. The fetus’ heart rate and your vital signs will be reassessed.
  2. If you are Rh negative, you may be given Rhogam. This is a specially developed blood product that can prevent an Rh negative mother's antibodies from reacting to Rh positive fetal cells.
  3. The chorionic villus tissue will be sent to the lab.

After the Procedure

You and your fetus will be monitored for a time after the procedure. Your vital signs and the fetal heart rate will be checked periodically for an hour or longer.

The CVS tissue will be sent to a specialty genetics lab for analysis. Counseling with a genetics specialist may be recommended depending on the test results.

You may experience some slight cramping and light spotting for a few hours after CVS.

You should rest at home and avoid strenuous activities for at least 24 hours. You should not douche or have sexual intercourse for two weeks, or until directed by your physician.

Notify your physician to report any of the following:

If a transabdominal procedure was performed, check the bandaged needle site on your abdomen for any bleeding or drainage of fluid.

Your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.

Online Resources

The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your physician. Please consult your physician with any questions or concerns you may have regarding your condition.

This page contains links to other Web sites with information about this procedure and related health conditions. We hope you find these sites helpful, but please remember we do not control or endorse the information presented on these Web sites, nor do these sites endorse the information contained here.

American College of Obstetricians and Gynecologists

Gene Tests

March of Dimes

National Center on Birth Defects and Developmental Disabilities

National Human Genome Research Institute

National Institutes of Health (NIH)

National Library of Medicine

National Women's Health Information Center


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