Ultrasound Scan May Harm Cells In the Fetal Brain
Associated Press
August 8, 2006; Page D4

WASHINGTON -- Exposure to ultrasound can affect fetal-brain development, a new
study suggests. But researchers say the findings, in mice, shouldn't discourage
pregnant women from having ultrasound scans for medical reasons.
When pregnant mice were exposed to ultrasound, a small number of nerve cells
in the developing brains of their fetuses failed to extend correctly in the
cerebral cortex.
"Our study in mice does not mean that use of ultrasound on human fetuses for
appropriate diagnostic and medical purposes should be abandoned," said lead
researcher Pasko Rakic, chairman of the neurobiology department at Yale
University School of Medicine.
However, he added, women should avoid unnecessary ultrasound scans until more
research has been done.
Joshua Copel, president-elect of the American Institute of Ultrasound
Medicine, said his organization tries to discourage "entertainment" ultrasound,
but considers sonograms important when there is a medical benefit.
"Anytime we're doing an ultrasound we have to think of risk versus benefit.
What clinical question are we trying to answer," Dr. Copel said. "It may be very
important to know the exact dating of pregnancy, it's certainly helpful to know
the anatomy of the fetus, but we shouldn't be holding a transducer on mom's
abdomen for hours and hours and hours."
Dr. Rakic's paper said that while the effects of ultrasound in human-brain
development aren't yet known, there are disorders thought to be the result of
misplacement of brain cells during their development. "These disorders range
from mental retardation and childhood epilepsy to developmental dyslexia, autism
spectrum disorders and schizophrenia," the researchers said.
Their report is in today's edition of Proceedings of the National Academy of
Sciences.
Early ultrasound scans are done to determine the exact week of the pregnancy
and they are also done later to check for anatomical defects and other problems.
However, some expectant parents have sought scans to save as keepsakes even
when they weren't medically necessary, a practice the Food and Drug
Administration discourages.
In Dr. Rakic's study, pregnant mice were exposed to ultrasound for various
amounts of time ranging from a total exposure of five minutes to 420 minutes.
After the baby mice were born their brains were studied and compared with those
of mice whose mothers hadn't been exposed to ultrasound.
The study of 335 mice concluded that in those whose mothers were exposed to a
total of 30 minutes or more, "a small but statistically significant number" of
brain cells failed to grow into their proper position and remained scattered in
incorrect parts of the brain. The number of affected cells increased with longer
exposures.

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