New Screen for Down Syndrome

A noninvasive screen for Down syndrome has shown high accuracy in a recent study and offers a significant advantage over current screening. The findings were published in the November 10, 2005, issue of The New England Journal of Medicine.

The new screen uses a blood test that analyzes the level of a protein and hormone in the mother's blood, combined with an ultrasound view of the thickness of skin on the back of the baby's neck, known as nuchal translucency, or NT. Test results are available within five days, often before a woman is starting her second trimester of pregnancy. This combination approach determines the odds that the baby might have Down syndrome and offers the woman the option of having a prenatal diagnosis for abnormalities within the first trimester. The researchers found the test provided higher detection, 87%, in the first trimester, compared to 81% for the best second-trimester screening method.

The first-trimester screening was performed on 38,167 patients, of whom 117 were found to have a fetus with Down syndrome. Women who had a positive result were given the option to have the finding confirmed with chorionic villus sampling (CVS) or amniocentesis.

"These results will undoubtedly change national practice. All pregnant women should have the option of early screening for Down syndrome in their first trimester,” noted Mary E. D'Alton, chair of the department of obstetrics and gynecology at Columbia University College of Physicians and Surgeons (New York, NY, USA). "Down syndrome screenings based on either maternal age alone, or an ultrasound or sonogram, are no longer justified protocols.”




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