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In diathermy, high-frequency electrical currents are used to heat deep muscular tissues. The heat increases blood flow, speeding up recovery. Doctors also use diathermy in surgical procedures by sealing blood vessels with electrically heated probes.

The term diathermy is derived from the Greek words therma, meaning heat, and dia, meaning through. Diathermy literally means heating through.


The therapeutic effects of heat have long been recognized. More than 2,000 years ago, the Romans took advantage of heat therapies by building hot-spring bathhouses. Since then, various methods of using heat have evolved. In the early 1890s, French physiologist Arséne d'Arsonval began studying the medical application of high-frequency currents. The term diathermy was coined by German physician Carl Franz Nagelschmidt, who designed a prototype apparatus in 1906. Around 1925, United States doctor J. W. Schereschewsky began studying the physiological effects of high-frequency electrical currents on animals. It was several years, however, before the fundamentals of the therapy were understood and put into practice.


Diathermy can be used to treat arthritis, bursitis , and other conditions involving stiff, painful joints. It is also used to treat pelvic infections and sinusitis. A benefit of diathermy is that it is a painless procedure that can be administered at a clinic. Also, if the treatment relieves pain , then patients can discontinue pain killers and escape their high cost and side effects.


Diathermy involves heating deep muscular tissues. When heat is applied to the painful area, cellular metabolism speeds up and blood flow increases. The increased metabolism and circulation accelerates tissue repair. The heat helps the tissues relax and stretch, thus alleviating stiffness. Heat also reduces nerve fiber sensitivity, increasing the patient's pain threshold.

There are three methods of diathermy. In each, energy is delivered to the deep tissues, where it is converted to heat. The three methods are:

  • Shortwave diathermy. The body part to be treated is placed between two capacitor plates. Heat is generated as the high-frequency waves travel through the body tissues between the plates. Shortwave diathermy is most often used to treat areas like the hip, which is covered with a dense tissue mass. It is also used to treat pelvic infections and sinusitis. The treatment reduces inflammation. The Federal Communications Commission regulates the frequency allowed for short-wave diathermy treatment. Most machines function at 27.33 megahertz.
  • Ultrasound diathermy. In this method, high-frequency acoustic vibrations are used to generate heat in deep tissue.
  • Microwave diathermy. This method uses radar waves to heat tissue. This form is the easiest to use, but the microwaves cannot penetrate deep muscles.

Diathermy is also used in surgical procedures. Many doctors use electrically heated probes to seal blood vessels to prevent excessive bleeding. This is particularly helpful in neurosurgery and eye surgery. Doctors can also use diathermy to kill abnormal growths, such as tumors, warts , and infected tissues.


To keep patients from sweating, patients are usually asked to remove clothing from the body part being treated. If a patient sweats, the electrical currents may pool in the area, causing burns . Also, clothing containing metal must be removed, as must earrings, buttons, barrettes, or zippers that contain metal. Watches and hearing aids should be removed because the therapy may affect their function.

Practitioners of surgical diathermy should steer clear of alcohol-based solutions to prepare and cleanse the skin. These preparations can create a flammable vapor and cause burns and fires.


Patients with metal implants should not undergo diathermy treatment because the metal can act as a conductor of heat and result in serious internal burns. Female patients with metallic uterine implants, such as an IUD, should avoid treatment in the pelvic area. Diathermy should not be used in joints that have been replaced with a prosthesis or in those with sensory impairment who may not be able to tell if they are burning. Furthermore, pulsed shortwave diathermy should be avoided during pregnancy , as it can lead to abnormal fetal development.

Patients with hemophilia should avoid the treatment because the increased blood flow could cause them to hemorrhage.

Side effects

Some patients may experience superficial burns. Since the therapy involves creating heat, care must be taken to avoid burns, particularly in patients whose injuries have caused decreased sensitivity to heat. Also, diathermy may affect pacemaker function.

Female patients who receive treatment in the lower back or pelvic area may experience an increased menstrual flow.

Research & general acceptance

For years, physiotherapists and physical therapists have used diathermy as a routine part of physical rehabilitation.

Training & certification

It is recommended that those who treat patients with diathermy complete a course in shortwave therapy and should retake courses every five years to stay updated on procedures. Physiotherapists should also stay updated by reading appropriate medical journals.



Magill's Medical Guide. Englewood Cliffs, NJ: Salem Press Inc., 1998.

The Merck Manual. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Michlovitz, Susan L. Thermal Agents in Rehabilitation. Philadelphia: F.A. Davis Company, 1996.

Thom, Harald. Introduction to Shortwave and Microwave Therapy. Springfield, IL: Charles C. Thomas, 1966.


"Diathermy." (19 June 2000).

Lisa Frick

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diathermy (dī´əthûr´mē), therapeutic measure used in medicine to generate heat in the body tissues. Electrodes and other instruments are used to transmit electric current to surface structures, thereby increasing the local blood circulation and facilitating and accelerating the process of absorption and repair. Diathermy is used for arthritis, bursitis, and other disorders of the tendons and muscles, as well as for certain other conditions requiring tissue repair. Because of the high-frequency current used in shortwave diathermy, care must be taken to avoid burning the patient's skin or injuring the deeper tissues.

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diathermy (dy-ă-therm-i) n. the production of heat in a part of the body by means of a high-frequency electric current passed between two electrodes placed on the patient's skin. The principle of diathermy is utilized in various surgical instruments (e.g. d. knives, forceps, and scissors) to coagulate tissues and seal off blood vessels. d. snare (or needle) a snare (or needle) used to destroy unwanted tissue and to remove small superficial neoplasms. See also electrosurgery.

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