In the natural sciences, the term diathermy means "electrically induced heat" and is commonly used for muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 relaxation. It is also a method of heating tissue electromagnetically or ultrasonically for therapeutic purposes in medicine.

Surgical uses

Surgical diathermy is usually better known as "electrosurgery

Electrosurgery

Electrosurgery is the application of a high-frequency electric current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate tissue. . Its benefits include the ability to make precise cuts with limited blood loss...

." (It is also referred to occasionally as "electrocautery", but see disambiguation below). Electrosurgery and surgical diathermy involve the use of high frequency A.C. electrical current in surgery

Surgery

Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...

 as either a cutting modality, or else to cauterize small blood vessels to stop bleeding. This technique induces localized tissue burning and damage, the zone of which is controlled by the frequency and power of the device.
Some sources insist that electrosurgery

Electrosurgery

Electrosurgery is the application of a high-frequency electric current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate tissue. . Its benefits include the ability to make precise cuts with limited blood loss...

 be applied to surgery accomplished by high frequency A.C. cutting, and that "electrocautery" be used only for the practice of cauterization with heated nichrome

Nichrome

Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various...

 wires powered by D.C. current, as in the handheld battery-operated portable cautery tools.

History

Diathermy was used for the first time on gynecology by the spanish doctor Celedonio Calatayud

Celedonio Calatayud

Celedonio Calatayud Costa was a spanish scientist and radiologist, remembered for his achievements on radiology and electrology. He pioneered the use of radiology and electrology in Europe for both diagnostics and therapeutical purposes, introducing radiotherapy in Spain in 1906...

 in 1910.

Trivia

Medical Diathermy devices were used to cause interference to German radio beams used for targeting night time bombing raids in WWII during the Battle of the Beams

Battle of the beams

The Battle of the Beams was a period early in the Second World War when bombers of the German Air Force used a number of increasingly accurate systems of radio navigation for night bombing. British "scientific intelligence" at the Air Ministry fought back with a variety of increasingly effective...

.