What you can expect

By Mayo Clinic Staff

Chorionic villus sampling is usually done in an outpatient facility or the health care provider's office.

During the procedure

First, your health care provider will use ultrasound to determine your baby's gestational age and the position of the placenta. You'll lie on your back on an exam table and lift your shirt to expose your abdomen. Your health care provider will apply a special gel to your abdomen, and then use a small device known as an ultrasound transducer to show your baby's position on a monitor.

Next, your health care provider will use the ultrasound image as a guide and take the tissue sample from the placenta. This can be done through your cervix (transcervical) or your abdominal wall (transabdominal).

  • Transcervical chorionic villus sampling. If the placenta is in a favorable position, your health care provider might take the sample through your cervix. After cleansing your vagina and cervix with an antiseptic, he or she will open your vagina with a speculum and insert a thin, hollow tube through your cervix. When the catheter reaches the placenta, gentle suction will be used to remove a small tissue sample. You might feel cramping while the tissue sample is removed.
  • Transabdominal chorionic villus sampling. If the placenta isn't clearly accessible through the cervix or you have a cervical infection, such as herpes, your health care provider might take the sample through a needle inserted into your uterus. After cleansing your abdomen with an antiseptic, he or she will insert a long, thin needle through your abdominal wall and into your uterus. You might notice a stinging sensation when the needle enters your skin, and you might feel cramping when the needle enters your uterus. The tissue sample from the placenta will be withdrawn into a syringe, and the needle will be removed.

You'll need to lie still while the tissue sample is removed. The entire procedure usually takes about 30 minutes.

If your health care provider isn't able to remove an adequate amount of tissue on the first try, the procedure might need to be repeated.

After the procedure

After the tissue sample is removed, your health care provider might use ultrasound to monitor your baby's heart rate. You might experience a small amount of vaginal bleeding immediately after the procedure.

The tissue sample will be analyzed in a lab. Results might take a few days or a couple of weeks, depending on the complexity of the lab analysis.

Contact your health care provider if you have:

  • Fluid leaking from your vagina
  • Heavy bleeding
  • A fever
  • Uterine contractions
Oct. 10, 2012