Chorionic Villus Sampling

Chorionic Villus Sampling

Chorionic villus sampling (CVS) is a procedure done early in pregnancy in order to test for certain conditions.  A CVS can tell whether a baby has Down syndrome, cystic fibrosis or other genetic or chromosomal conditions.

Chorionic villi are tiny finger-shaped cells found in the placenta. The genetic material in chorionic villus cells is the same as that in the baby’s cells. During CVS, a sample of the chorionic villus cells is taken and is checked for problems. The procedure is generally done early in pregnancy, most often between the 10th and 13th weeks.

A CVS is performed usually by a Maternal Fetal Medicine specialist or a Geneticist who received special training in the procedure. The sample can be taken two different ways, through the cervix/vagina or through the abdomen. The route performed is determined based on the location of the placenta, uterus, and baby. Both methods are performed under ultrasound guidance.

Common reasons why women choose to have a CVS include maternal age > 35, an abnormal finding on ultrasound exam, or screening test for Down Syndrome, or a family or personal history of a genetic condition, such as cystic fibrosis, Tay Sachs disease of sickle cell disease. Chorionic villus sampling can be done earlier in pregnancy (at 10 to 13 weeks) than amniocentesis (usually done at 15 to 20 weeks). This allows you to know more information about the health of your baby and potentially make an earlier decision whether to continue or end the pregnancy.

Some symptoms seen after CVS include cramping, leakage of amniotic fluid, and vaginal spotting, which goes away in 1 to 2 days. You may feel some soreness where the needle was put in if you had the procedure done through the belly. CVS is known to increase the risk of miscarriage. This risk is thought to be similar to the risk of amniocentesis (1 or 2:400).

Chorionic villus sampling can occasionally cause bleeding that could result in mixing your blood and your baby’s. If you have Rh-negative blood, you will be given the Rh immune globulin vaccine (such as RhoGAM) to prevent Rh sensitization which could harm your baby if they have Rh-positive blood.

For further information or to schedule an appointment, please call our Maternal Fetal Care Center at (414) 805-6624.