Early Checking for Down's Syndrome: Still a Distant Dream
Still No Substitute for Second-Trimester Testing
For now, the two definitive tests for Down's syndrome and other chromosomal abnormalities are amniocentesis and chorionic villi sampling (CVS). Both carry a slight risk of miscarriage. Because CVS has a somewhat higher risk of miscarriage than amniocentesis, as well as a risk of malformations, fewer women request it.
Laboratory screening tests that can help a woman know her risks include plasma protein A concentration and free beta-hCG concentration. FASTER will determine the value of a combination approach and will involve both laboratory tests such as these and nuchal translucency.
"I couldn't agree more that [nuchal translucency] is still in the investigational stage," Ronald J. Wapner, MD, tells WebMD. For a woman who finds the risk of losing a normal pregnancy as the result of testing, screening tests at a proper center may be a realistic option, says Wapner, who is the director of maternal-fetal medicine and reproductive genetics at Jefferson Medical College in Philadelphia. Wapner reviewed the study for WebMD.
"This is an opinion article and not unbiased, because some of the authors are conducting an NIH [study]," Greggory DeVore, MD, tells WebMD. "First trimester screening really has no benefits other than detection of a few patients two weeks earlier into the pregnancy. The safest and most cost-effective screening is second-trimester ... screening plus genetic ultrasound. " DeVore, who was not involved in the article, is the medical director of Fetal Diagnostic Center of Pasadena, Calif.
- Although there are screening tests available for women in the first trimester of pregnancy to evaluate the risk of chromosomal abnormalities, these tests are not definitive.
- The nuchal translucency is the newest of such tests, and researchers are currently looking at its effectiveness in combination with other tests and comparing it to second-trimester screening.
- Two definitive tests for chromosomal abnormalities are amniocentesis and chronic villi sampling, but both of these carry a small risk of miscarriage.