This question raises a valid point. However since therapeutic ultrasound has been around since the 1940’s and no deleterious effects have been observed it doesn’t seem to be a major concern. In the case of thalidomide it was only around for about 5 years before they stopped selling it. So if therapeutic ultrasound was a major health concern with serious and common side effects I think it would have been removed from use a long time ago. As well keeping in comparison to thalidomide there are contraindications against using U/S for pregnant women because of the unknown effects it has on the growing fetus.