Biological effects of ultrasound.

In summary, there are many deficiencies and gaps in the current data base for ultrasound-induced bioeffects. More information is needed on the effects of low intensity ultrasound, the effects of pulsed ultrasound, the relationship between peak intensities and average intensities of pulsed ultrasound, the possibility of cumulative effects, and the possibility of long-term effects. Also, very little of the data, either positive or negative, has been verified by other laboratories. Although there is presently no evidence to indicate that diagnostic ultrasound involves a significant risk, the evidence is insufficient to justify an unqualified acceptance of safety. The potential for acute adverse effects has not been systematically explored, and the potential for delayed effects has been virtually ignored. Because of the difficulties involved in searching for and defining potential risks from exposure to low levels of chemicals, radiation, or other forms of energy, it is unreasonable to expect that in the near future, the degree of risk, if any, will be clearly defined for diagnostic ultrasound. As in other areas (e.g., the effects of ionizing radiation) no single study, epidemiological or experimental, can accomplish this goal. In the meantime, a prudent public health policy calls for judicious use of diagnostic ultrasound, using it only when diagnostic benefits to patients are indicated, and keeping any exposure to diagnostic ultrasound as low as practicable, consistent with its intended purpose.