Chorionic Villus Sampling (CVS)

Chorionic villus sampling is most commonly done by a Reference perinatologist Opens New Window 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 Reference cervix Opens New Window) 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 Reference uterus Opens New Window, 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 Reference 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.

An ultrasound will be used to help your doctor guide the catheter through your cervix to the placenta. 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 baby's heart rate can also be checked during the procedure using ultrasound. For more information, see the topic Reference Fetal Ultrasound.

When the catheter is correctly placed, a sample of chorionic villus cells will be collected.

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

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