Diagnostic ultrasound ranks along with the stethoscope as one of the safest analytical tools available to medicine. This does not mean, however, that its potential effects can be completely ignored.

At the present time, there is no way to predict theoretically whether effects will occur under diagnostic conditions. However, in a general sense, two fundamentally different mechanisms have been identified through which ultrasound may produce potentially adverse biological effects. One is heating and the other is acoustic cavitation. Of course, the  sound wave itself exerts mechanical stresses on the propagating media including biological tissues. In addition to the stresses that change with time at the frequency of the sound field, the propagating medium also experiences steady forces. In fluids, this leads to macroscopic streaming. Particles, including bubbles, may be segregated in standing waves or driven relative to the suspending medium in traveling waves. At the present time, however, these purely mechanical forces have not been associated with any adverse reactions in laboratory animals under diagnostically relevant conditions.