Study Shows Potential Dangers of Ultrasound in Fetal Development

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SonographyStudy Shows Potential Dangers of Ultrasound in Fetal DevelopmentAug. 24, 2006 https://www.asrt.org/content/News/IndustryNewsBriefs/Sono/studyshows062408.aspx A new study reports that prolonged and frequent use of ultrasound on pregnant mice causes brain abnormalities in the developing mouse fetus. Researchers said that the study findings support warnings by the U.S. Food and Drug Administration against the use of medically nonindicated or commercial prenatal ultrasound videos.

While ultrasound generally is considered safe if properly used when information is needed about a pregnancy, the FDA has expressed concern over the burgeoning use of the technology for entertainment purposes, such as in "keepsake" pictures and videos.

There is evidence that the exposure of pregnant mice and nonhuman primates to ultrasound waves may affect the behavior of their exposed offspring. Additionally, studies have shown that the frequent exposure of the human fetus to ultrasound waves is associated with a decrease in newborn body weight, an increase in the frequency of left-handedness, and delayed speech.

Because ultrasound energy is a high-frequency mechanical vibration, researchers hypothesized that it might influence the migration of neurons in a developing fetus. Neurons in mammals multiply early in fetal development and then migrate to their final destinations. Any interference or disruption in the process could result in abnormal brain function.

In the study, researchers injected more than 335 fetal mice at embryonic day 16 with special markers to track neuronal development. Exposure to ultrasound waves for 30 minutes or longer caused a small but statistically significant number of neurons to remain scattered within inappropriate cortical layers and in the adjacent white matter. The magnitude of dispersion of labeled neurons was highly variable but increased with duration of exposure to ultrasound waves.

"We have observed that a small but significant number of neurons in the mouse embryonic brain do not migrate to their proper positions in the cerebral cortex following prolonged and frequent exposure to ultrasound," said Pasko Rakic, M.D., of the Yale School of Medicine in New Haven, Conn. The study appeared in the Aug. 7 edition of the Proceedings of the National Academy of Sciences.

Dr. Rakic emphasized that the study does not mean that ultrasound use on human fetuses for appropriate diagnostic and medical purposes should be abandoned.

"On the contrary: ultrasound has been shown to be very beneficial in the medical context," he said. "Instead, our study warns against its non-medical use."

The research team intends to conduct research on nonhuman primates to see if a similar effect is occurring in the developing larger brains, which are more similar to humans. Those upcoming studies should provide information that will be more directly applicable to uses of ultrasound waves in humans.

By Laurie Volkin and Richard S. Dargan, ASRT Contributing Writers

 

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