Differences Between Electrosurgery (diathermy) & Electrocautery.

Do you know that Electrosurgery (also called diathermy) and Electrocautery are essentially different modalities?

Yes, that’s true and before you plan to buy a machine, you should have a clear understanding of this difference!

It’s all about ' modifying ' electric current in different ways to perform different surgical tasks like coagulation, cutting etc.

So, why and how is current ‘modified’ OR ‘ manipulated ’ ?

The normal frequency of A/C current that we use is around 50/60 Hz. Although this frequency is ideal for use in household electrical appliances, it has the potential of stimulating neural and skeletal tissues in human body. So, if this frequency is utilized in Electrosurgical or Electrocautery procedures, muscles may contract in a violent fashion and result in severe injury.

How is this problem solved?

Electrosurgery and Electrocautery machines are designed to increase the frequency of current from 50/60 Hz to at least " above 300,000 Hz" ; (HFAC or High Frequency Alternating Current). This frequency is so high that neural or skeletal muscle stimulation ceases to exist at this point. So, the current becomes usable for use on living tissues.

Let’s now turn towards the real question: How is Electrocautery different from Electrosurgery (diathermy) ?


In electrocautery, the high frequency electric current passes through a metal wire causing it to “heat up”. This heated wire is then applied to the tissue resulting in a ‘burn’ or ‘coagulation’ in the target tissue. Remember, in electrocautery, the current DOES NOT pass through the living tissue; instead it passes through the metal wire (which becomes hot due to electrical resistance).

Electrocautery equipment is routinely used by Dermatologists, Urologists and ophthalmologists etc, since their jobs mostly require handling of superficial tissues.

Electrosurgery (Diathermy)

The term diathermy is a Greek term which means “ heating through ”. This term suggests how HFAC (high frequency electric current) flows during electrosurgery.

Electrosurgery works by passing electric current through living tissues of the body to achieve the following results:

Coagulation – enhancing blood clot formation

Cutting – tissue cell destruction through heat

Fulguration – Cell wall destruction by dehydration

Furthermore, electrosurgery can be Monopolar or Bipolar:


The pathway of HFAC (high frequency alternating current) in monopolar electrosurgery is as follows:

The Electrosurgical Unit produces HFAC which then passes through the Electrode. During passage through electrode, it performs cutting, coagulation or fulguration. After this, the current enters body tissues and reaches the Grounding/Return electrode which collects the current and provides passage to allow it to flow back to Electrosurgical Unit.


As the name suggests, a bipolar technique requires the use of a forceps-style electrode, such that both tips of the forceps function as the poles through which electric current flows. The target body tissue is held between the tips of forceps-style electrode and desired action (cutting, coagulation etc.) is performed. In this case, one tip of the forceps 'releases' current, which is 'picked-up' by the other tip of the forceps, after it has passed through the body tissue.

Now that you are aware of the science behind Electrocautery and Electrosurgery, you are in a better position to choose a machine that suits your working requirements!


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