A blood test that has recently become available for pregnant women is demonstrating 80 percent reliability in identifying a number of different types of fetal problems, according to a local specialist.
Dr. Greggory R. DeVore said the test, Maternal Serum Alpha-Fetroprotein screening, is proving valuable in detecting incorrectly estimated due dates, multiple pregnancies, birth defects, fetal stress and impending fetal death."When a pregnant woman begins prenatal care, blood tests are done routinely," said DeVore, medical director of the Intermountain Fetal Diagnostic and Treatment Center at LDS Hospital. "This testing identifies for the mother any potential problems with her unborn child. AFP screening gives the mother's physician another important tool to use to identify other potential risk factors."
DeVore said that AFP is a chemical made by the fetus, and is evident in the amniotic fluid. "Higher- or lower-than-average levels of AFP are indications of potential problems," he said. "But it is important to understand that an abnormal blood test does not prove that the baby has a birth defect. It only means that other tests are needed, such as ultrasound or amniocentesis, to determine whether a problem actually exists."
The specialist said MS/AFP was first used to screen for neutral tube defects (malformations involving the brain and spinal column), that occur in one of every 1,000 pregnancies. But now physicians have found that elevated MS/AFP levels can indicate multiple pregnancies, abdominal defects, fetal stress due to placental problems, impending fetal death, and incorrectly estimated due dates.
In addition, lower-than-average MS/AFP levels can indicate Down's syndrome.
De Vore said the benefit of the screening is that a prenatal diagnosis may alter how the mother and her unborn child are cared for during pregnancy and delivery.
A specialist in caring for high-risk mothers and their unborn children, De Vore added that "should an abnormal value show up, the mother is always counseled as to any further testing, as well as to the consequences of any detected abnormality. But the AFP test is simply a screen, and not all abnormal values mean something is wrong"
The MS/AFP screen, he advised, should be done as soon as possible after the 15th week and no later than the 20th week of pregnancy. The procedure has become an accepted standard of care in the United States and is recommended by the American College of Obstetricians and Gynecologists.