Table 1 Principles of electrosurgery for endometrioma

Electrosurgery application

The thickness of the capsule of an endometrioma can be up to 3.0 mm and varies between cysts, but may also change within the same cyst. During the application of HF energy for destruction of an endometriotic lesion by a thermal effect, it is difficult to assess the changes in the tissue. Whereas the impact on superficial tissue may be visible by change of colour and vaporisation, coagulation of deeper structures is more difficult to observe. The surgeon needs to be aware of the exact HF effect of each instrument and various application forms. Coagulation or vaporisation of the ovarian cyst should inactivate endometriotic lesions superficially and respect the underlying tissue. Uncontrolled application of heat or deep coagulation may result in destruction of healthy tissue, primordial follicles and/or blood supply of the ovary, with severe consequences for ovarian function.

Monopolar energy

Cutting current is unmodulated alternating current, and vaporises or cuts the tissue for superficial ablation and deeper coagulation effect. Coagulation current is modulated alternating high voltage current and has a higher thermal spread, which leads to deeper coagulation of the tissue. Blended current is a mixture of cutting and coagulation currents, and is generated by altering the time that the current is applied. The more concentrated the energy, the greater is the thermodynamic effect. Current density depends on the size of the electrode (a smaller electrode may require a lower power setting). Use of monopolar diathermy, with a low power setting and small contact surface, provides better control of the tissue effect.

Argon beam coagulation

With this instrument, ionised argon gas carries electrons from the electrode to the tissue. The gas stream produces a monopolar tissue effect depending on the diameter of the beam and the distance between the beam and the target. The tissue effect is similar to that achieved by monopolar coagulation, but allows treatment of wider superficial areas.

Bipolar energy

Bipolar diathermy is a very useful technique to coagulate endometriosis in a safer way than monopolar diathermy. The current passes across the tissue between the two jaws of the instrument. The tissue temperature could be up to 300 400°C at the point of maximum current flow. The penetration into the tissue can be up to 10 12 mm, depending on the power setting and the application time.