One spring day in 2013, Dr. Jayme Sloan had bad news for Stacie Chapman, who was nearly three months pregnant. Her unborn child had tested positive for Edwards syndrome, a genetic condition associated with severe birth defects. If her baby — a boy, the screening test had shown — was born alive, he probably would not live long.
Sloan explained that the test — MaterniT21 PLUS — has a 99 percent detection rate. Though Sloan offered additional testing to confirm the result, a distraught Chapman said she wanted to terminate the pregnancy immediately.
What she — and the doctor — did not understand, Chapman’s medical records indicate, was that there was a good chance her screening result was wrong. There is, it turns out, a huge and crucial difference between a test that can detect a potential problem and one reliable enough to diagnose a life-threatening condition for certain. The screening test only does the first.
Sparked by the sequencing of the human genome a decade ago, a new generation of prenatal screening tests, including MaterniT21, has exploded onto the market in the past three years. The unregulated screens claim to detect with near-perfect accuracy the risk that a fetus may have Down or Edwards syndromes, and a growing list of other chromosomal abnormalities.
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What are the dangers of false positive test results? In one of the three Stanford cases, the woman actually obtained a confirmatory test and was told the fetus was fine, but aborted anyway because of her faith in the screening company’s accuracy claims.
Companies that sell the screens stand behind their tests, saying they provide much more reliable assurance for expecting mothers than earlier screens. Some say their research focused first on how to accurately identify fetuses with potential genetic defects and only recently have they been able to get enough data to understand how often positive tests are wrong.
Read full original article: Oversold prenatal tests spur some to choose abortion
