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Chorionic Villus Sampling (CVS)

How To Prepare

You may be asked to drink a glass of fluid about an hour before the test so that your bladder is full. A full bladder makes it easier to do the test.

You will be asked to sign a consent form that says you understand the risks of the test and agree to have it done.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

Be sure to tell your doctor if you are allergic to any medicines, such as numbing medicines (local anesthetics), before the procedure.

How It Is Done

Chorionic villus sampling is most commonly done by a perinatologist in the doctor's office or the hospital. An overnight stay in the hospital usually is not needed unless problems occur during the procedure.

Transabdominal (through the belly) chorionic villus sampling or transcervical (through the cervix camera.gif) chorionic villus sampling can be done. The choice may depend on where the fetus and placenta are in the uterus.

Through the belly (transabdominal)

You will lie on your back on an examination table with your belly bare.

Gel will be rubbed on your belly to use with the ultrasound unit. An ultrasound device (transducer) that gives off and picks up sound waves will be passed over your belly. The reflected sound waves are sent to a computer to make a picture of the uterus, your baby, and the placenta on a screen. Your doctor or an ultrasound technician will look at the picture on the screen to help guide the needle used to collect a sample of the chorionic villus. Your baby's heart rate can also be checked during the procedure using ultrasound. For more information, see the topic Fetal Ultrasound.

Your skin where the needle will be put in is cleaned with alcohol and numbed with a medicine. Your doctor then puts a long thin needle through your belly and uterus to the placenta and collects a sample of the chorionic villus cells.

After the sample is collected, your doctor may listen to your baby's heart rate and check your blood pressure, pulse, and breathing.

Through the cervix (transcervical)

You will be asked to take off your clothes below the waist and drape a covering around your waist. You will then lie on your back on an examination table with your feet raised and supported by stirrups. This allows your doctor to look at your genital area.

Your doctor will put an instrument with curved sides (speculum) into your vagina. The speculum gently spreads apart the vaginal walls, allowing the inside of the vagina and the cervix to be seen. The cervix will be cleaned with a special soap.

WebMD Medical Reference from Healthwise

Last Updated: April 04, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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