New Down syndrome test reports fewer false positives

Jan 15, 2018

With increasing numbers of higher-risk older pregnant women, there's a new test available for those concerned about Down syndrome.

It's a DNA test called reflex DNA screening. British doctors say the new test is far quicker than current testing and produces a much smaller percentage of false positives results, according to the testing on 22,000 women in London.

The current standard test has a much higher rate of false positives and, if there is a positive, it can take weeks for a second test while caregivers counsel the pregnant woman.

Credit Queen Mary University of London

The new test uses two blood samples. If the first comes back positive, the second is immediately DNA tested. University at Buffalo OB/GYN Chair Dr. Vanessa Barnebei said use of the current tests varies.

"When I practiced in a large urban area on the East Coast, people were very anxious to have as much screening or testing as possible," said Barnebei. "When I practiced in a urban areas in the Midwest, much less so, but, still, the uptake is pretty high."

Barnebei said Down syndrome can occur at any age, but it's increasingly common as women become pregnant at a higher age, roughly a one in 100 chance for a 40-year-old pregnant woman. She said the test can be frightening.

"This patient is at increased risk, based on this combination of markers that we assessed and then we would have to call the patient, counsel her about the risk, what that means and then offer her additional testing," she said.