Instead of a needle, simple measurements rule out Down syndrome

Yale researchers have developed an algorithm that allows physicians to gauge the risk of Down syndrome in fetuses without resorting to amniocentesis, an invasive procedure that could cause a miscarriage. Instead, physicians rely on what is called an ultrasonic biometry algorithm, which measures risk based on a number of factors, including information gathered by ultrasound—measurements of the fetus’s upper arm and skin at the back of the neck.

In a study published in the May issue of the American Journal of Obstetrics and Gynecology, Ray O. Bahado-Singh, M.D., associate professor of obstetrics and gynecology, reported that the algorithm proved accurate in almost 80 percent of cases. Having this assessment allows parents to determine whether to proceed with amniocentesis.

Down syndrome is a congenital disorder caused by an extra chromosome 21. Children affected have mild to moderate mental retardation, shorter stature and flattened facial features. Women over 35 have a higher risk of giving birth to a child with Down syndrome, but using age alone physicians detect only about one in five cases, said co-author Joshua A. Copel, M.D., professor of obstetrics and gynecology and pediatrics. “Using blood tests and ultrasound we apply adjustments to the mother’s age-related risk,” Copel said. “This would mean fewer amniocenteses and a higher percentage of abnormal babies identified.”