Dr. David Toms, radiologist, discusses on his website an inconsistency found in the regulations of ultrasound power output for fetal scanning. The eye is a fluid filled sac with very delicate anatomy — there is a hard cap on the maximum power of ultrasound exposure allowed to pass through it for safety reasons.
However, this max amount is different for adults and the fetus. Strangely, the fetal eye is not protected as much as the adult eye. By quite a large margin, too.
Further strange, ultrasound devices do not accurately report the amount of ultrasound exposure in the lower regimes of power. Most all concerns about the limits for fetal scanning extend from known mechanisms of damage such as hemorrhaging and cavitation, but scientific evidence suggests the existence of other dangers.
It is almost as if regulatory authorities wish to remain absolutely ignorant of their own ignorance. There has even been talk of removing the upper power limit to allow practitioners to use as much ultrasound as desired with little to no baseline.
Dr. Toms says it best –
“Exposure limits are somewhat arbitrary, given the paltry amount of clinical and experimental data, but prudence would seem an important underlying principle. In view of this, a debate about removing all upper limits strikes me as being of questionable social responsibility.”