Chorionic villus sampling carries various risks, including:

  • Miscarriage. Overall, chorionic villus sampling carries a 1 in 100 risk of miscarriage. The risk of miscarriage appears to be slightly higher when the tissue sample is taken through the cervix (transcervical) rather than the abdominal wall (transabdominal). The risk of miscarriage also increases if the baby is smaller than normal for his or her gestational age.
  • Rh sensitization. Chorionic villus sampling might cause some of the baby's blood cells to enter your bloodstream. If you have Rh negative blood and you haven't developed antibodies to Rh positive blood, you'll be given a drug called Rh immunoglobulin after the test to prevent you from producing antibodies against your baby's blood cells. A blood test can detect if you've begun to produce antibodies.
  • Infection. Rarely, chorionic villus sampling might trigger a uterine infection.

Some older studies suggested that chorionic villus sampling might cause defects in a baby's fingers or toes. However, the risk appears to be a concern only if the procedure is done before week nine of pregnancy.

Remember, chorionic villus sampling is typically offered when the test results might have a significant impact on the management of the pregnancy. Ultimately, the decision to have chorionic villus sampling is up to you. Your health care provider or genetic counselor can help you weigh all the factors in the decision.

Oct. 10, 2012