Researchers Have Developed A Non-Invasive Way To Detect Fetal Anemia

Yale scientists have successfully used a non-invasive technology -- Doppler ultrasound -- to detect whether or not a baby in utero is anemic. Doppler allows them to eliminate the risks accompanying traditional invasive tests for this problem.
"Invasive procedures place the fetus in unnecessary danger," said Giancarlo Mari, MD, associate professor of obstetrics and gynecology at Yale School of Medicine, and the study's 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 babies 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, 2000, issue of The New England Journal of Medicine, the study showed that anemic fetuses have a higher blood flow velocity -- the rate of blood flow in arteries and veins -- in 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 far less expensive than amniocentesis and cordocentesis, and, said Mari, "The procedure is also easy to perform in the hands of experienced operators."

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