Chorionic villus sampling seen safe

NEW YORK (Reuters Health) - Testing for genetic defects early in pregnancy through chorionic villus sampling, or CVS, does not appear to raise the risk of fetal loss.

CVS involves using a needle to collect samples of the embryonic structure that goes on the form the placenta. The process can be performed as early as 10 weeks into pregnancy, and provides cells of fetal origin that can be examined for chromosomal abnormalities.

There has been concern that the procedure might cause miscarriage, but in the current study the fetal loss rate following chorionic villus sampling was no different than the rate among pregnant women who did not undergo an invasive procedure.

"With the recent recommendations for screening for chromosomal abnormalities...demand for prenatal diagnosis are expected to increase," the researchers write in the medical journal Obstetrics & Gynecology. "Providing reliable information on the fetal loss rate and potential risk factors for fetal loss is important during counseling before undergoing an invasive procedure."

Using information from their institution's prenatal diagnosis database for all pregnant women seen between 1990 and 2006, Dr. Anthony O. Odibo and colleagues at the Washington University School of Medicine in St. Louis compared the fetal loss rate before 24 weeks gestation in women who underwent CVS to that of women who did not have any invasive procedure.

The fetal loss rates among the 5148 women who had chorionic villus sampling and the 4803 women who had no procedure were 2.7 percent and 3.3 percent, respectively -- a nonsignificant difference from a statistical standpoint.

Nonetheless, some women seemed to have a higher risk of miscarriage after the procedure -- among them, those of African-American race and those younger than 25 years of age.

The information from the study could be useful for women considering this method of prenatal diagnosis, Odibo's team concludes.

SOURCE: Obstetrics & Gynecology, October 2008.