Therapeutic ultrasound is a modality commonly used by physical therapists. Ultrasound therapy works by driving sound waves into the tissue to help alleviate pain, inflammation and muscles spasms while increasing range of motion. Therapeutic ultrasound can be used to produce both thermal and non-thermal changes in the tissue. While this type of ultrasound is safe for treating many conditions, there are contraindications for this therapy.
Eyes
Ultrasound therapy is contraindicated over the eyes. In the book "Thermal Agents in Rehabilitation," author Susan L. Michlovitz explains that due to the poor blood supply to the eye, the heat from the ultrasound can build up. This might lead to retinal damage and increased risk for cataracts.
Pregnant Women
Therapeutic ultrasound should not be applied to the abdomen of pregnant women. Unlike diagnostic ultrasound, in which harmless sound waves are used to provide an image of the developing fetus, ultrasound therapy often involves deep penetrating heat and vibration. Health Canada's Guidelines for the Safe Use of Ultrasound suggests that ultrasound therapy could overheat the fetus which can possibly lead to a birth defect, especially if administered during the first trimester.
Testicles
Ultrasound therapy applied over the testicles is contraindicated, due to the potential for producing short-term heat-related sterility.
Cancer
Application of ultrasound thereapy to cancerous tissue should be avoided. According to Thermal Agents in Rehabilitation, research suggests this could promote metastasis, or spreading of the cancer cells to other parts of the body.
Infection
Localized tissue or bone infections are contraindicated for treatment with therapeutic ultrasound, explains Health Canada. The heat from the ultrasound therapy increases the likelihood of spreading the infection.
Pacemakers
Health Canada discourages the use of ultrasound over the chest of patients with cardiac pacemakers. The sound waves could interfere with the performance of the pacemaker.
Thromboembolic Disease
Patients with thromboembolic disease, or blood clots, should avoid ultrasound therapy, explains Health Canada, since the heat might increase the risk of a clot dislodging.
Laminectomy
Therapeutic ultrasound should not be performed over the spine after a laminectomy, suggests the Family Physiotherapy Centre of London. Doing so carries risks of injury to the spinal cord.
Metal Implants
Due to the tendency of metal to have higher heat conductivity than tissue, ultrasound therapy should never be used directly over metal implants because of the risk for burns.
References
- "Thermal Agents in Rehabilitation"; Susan L. Michlovitz, 1996
- Health Canada: Guidelines for the Safe Use of Ultrasound
- Family Physiotherapy Centre of London: Therapeutic Ultrasound
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