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Researchers study new screening method for Down syndrome
Screening could be done earlier, more accurately
ATLANTA (CNN) -- Researchers at New York Presbyterian Hospital and Columbia University are evaluating a new screening method for Down syndrome that could detect cases earlier and more accurately. The project is called FASTER (First And Second Trimester Evaluation of Risk).
Down syndrome is one of the leading causes of mental retardation and serious birth defects. If successful, the new screening method could help alleviate some of the anxiety many women experience with the current Down's test, which is administered in the second trimester of pregnancy.
"One of the most common complaints I have heard from patients over the years from offering second trimester screening is that they would much prefer to have this information much earlier in pregnancy," said Dr. Fergal Malone, a perinatologist at Columbia University.
Current tests have flaws
Any woman, regardless of her age, health or family history, can have a baby with Down syndrome. The current detection test, a blood test known as the "AFP" or "triple screen," is usually offered to women who are 15 to 20 weeks pregnant.
The test can detect 60 percent to 65 percent of Down syndrome cases, but it isn't always accurate.
"I knew a little bit going into it and that there might be a chance I'd get a false positive," said Susan Loeffler, who had a triple screen when she was four months pregnant. But when her results came back positive, she said, "I remember thinking 'Oh, brother, here we go,' because I had done some reading and I knew I had a lot of choices ahead or I could do nothing."
A positive AFP result must be confirmed with amniocentesis, a more invasive procedure that is accurate, but can cause miscarriage. Moreover, getting the results can take weeks.
Though her amniocentesis found no evidence of Down syndrome, Loeffler, whose baby is due in June, said the uncertainty and waiting were "frightening."
Initial reports promising
In the FASTER study, researchers will determine whether they can successfully screen for Down syndrome earlier in pregnancy and whether the new methods have a higher detection rate and fewer false positive results than current tests.
The new screening method involves two tests, both conducted in the first trimester of pregnancy -- between 10 and 14 weeks. In the first, doctors use an ultrasound exam to measure the skin thickness at the back of the fetus's neck. The thicker it is, the higher the chance of Down syndrome. The second step is a blood test that measures certain proteins and hormones in the mother's blood.
"Initial reports," said Malone, "while they're still real preliminary, would suggest that that package will detect 85 to 90 percent of cases of Down syndrome during the first trimester of pregnancy." That's a substantially higher detection rate than the current test offers.
But Malone and others are concerned that the new screening tests may already be in use in some doctors' offices. "And that's a potential problem," Malone explained, "because there's already evidence that when performed poorly, without quality control, (the test) actually does more harm than good."
The project is funded by the National Institutes of Health and the affiliated National Institute of Child Health and Human Development. It will last for three years.
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