Chorionic villus sampling carries various risks, including:

  • Miscarriage. The risk of miscarriage after chorionic villus sampling is about the same as that associated with transabdominal second-trimester amniocentesis — around .7 percent. The risk of miscarriage might increase 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 an injection of a blood product called Rh immune globulin after chorionic villus sampling. This will prevent your body from producing Rh antibodies that can cross the placenta and damage the baby's red blood cells. A blood test can detect if you've begun to produce antibodies.
  • Infection. Very 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 10 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. 17, 2015