Yale scientists have successfully used a non-invasive technology called Doppler ultrasound to detect whether or not a fetus is anemic, eliminating the risks accompanying traditional invasive tests for the deficiency.
"Invasive procedures place the fetus in unnecessary danger," said Giancarlo Mari, M.D., associate professor of obstetrics and gynecology at Yale School of Medicine and the study1s lead author. "In more than 70 percent of cases, the fetuses tested were either non-anemic or mildly anemic and an invasive procedure could have been either avoided or delayed."
Between one and two in every 1,000 pregnancies in the U.S. is at risk of having a fetus that may develop anemia, an oxygen deficiency in the blood. A fetus that develops anemia may require transfusion because he/she is at risk of dying. However, only between 10 and 20 percent of the fetuses at risk for anemia will develop the deficiency.
Diagnosis of fetal anemia is currently performed using invasive procedures such as amniocentesis and cordocentesis. Both carry a risk of death to the fetus and if an initial sample does not demonstrate anemia, the timing of repeat invasive procedures is arbitrarily determined.
Published in the January 6 issue of New England Journal of Medicine, the study shows that anemic fetuses have a higher blood flow velocityÐrate of blood flow in arteries and veinsÐin cerebral arteries than non-anemic fetuses. Doppler ultrasound was used to test fetal blood velocity and to determine fetal anemia.
The assessment of fetal blood velocity with Doppler ultrasound detected all the moderately and severely anemic fetuses, with a false positive rate of 15 percent. Doppler study can be performed in three to five minutes and does not pose any risk to the mother and the fetus. The procedure is also far less expensive than amniocentesis and cordocentesis.
"By using Doppler ultrasound to assess the velocity of blood flow, we can save about $50 million each year in the United States alone," said Mari. "The procedure is also easy to perform in the hands of experienced operators."
The data used in the study were compiled at eight medical centers in the United States, Europe, South America and Asia.
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