Electrosurgical loop electrodes: choosing the right loop for the procedure

How a loop electrode works

A loop electrode concentrates current along a thin wire. Where the wire touches tissue, the current density is high enough to vaporise cell water and separate tissue, producing a clean cut with a limited zone of thermal effect when the settings are right. The same loop can then be used with a coagulation waveform for haemostasis.

Most loops are monopolar: current passes from the loop through the patient to a neutral electrode. Bipolar designs keep the return path inside the instrument and are used mainly where a conductive saline medium is needed, such as bipolar hysteroscopic resection. Which type you can use is dictated by your generator and the instrument.

LEEP loop electrode and diathermy loop shapes

For loop excision of the cervical transformation zone, a LEEP loop electrode is selected by width and depth to match the lesion and cervix. Wire loops come in different widths and depths, and many clinics keep several sizes available so that the specimen can be removed in one pass where possible. A diathermy loop with a very thin wire reduces tissue distortion but must be handled carefully, since a loop that is too small or used with too much power can char the specimen margin.

Insulated shafts and a well-fitting handle matter as much as the loop itself. Inspect the insulation before each use, confirm the loop seats firmly in the pencil, and use a smoke evacuator, since LEEP generates plume close to the clinician. Smoke evacuation for laser and LEEP is covered separately.

Loops in hysteroscopic resection

In operative hysteroscopy, loops are mounted on a working element inside a resectoscope. The Richard Wolf Princess resectoscope is a slim 7 mm / 21 Fr continuous-irrigation instrument, expandable to 8 mm. According to the manufacturer it is a hybrid design that can be used for monopolar and bipolar resection with the same basic instrument, and a rotating double sheath lets the working element turn 360 degrees while the outer sheath stays still.

When choosing between monopolar and bipolar resection, remember the medium. Monopolar resection needs a non-conductive distension fluid, while bipolar resection works with saline. This affects fluid management protocols in the theatre and should be agreed with the gynaecology team before purchase.

Electrosurgical loop hysterectomy: the MetraLOOP system

For laparoscopic supracervical hysterectomy, the BOWA MetraLOOP allows the uterus to be detached quickly and precisely with a loop. Two loop diameters, 100 mm and 175 mm, adapt the system to small and large uteri. The instrument has a diameter of 5 mm with ceramic insulation, the inner and outer shafts are reusable and the loops are single-use, which keeps cutting performance consistent.

MetraLOOP works with common HF generators and is optimised for the dedicated MetraLOOP mode of the BOWA ARC 400. A COMFORT version stores preferred settings and documents the number of uses.

Generator settings and common mistakes

Start with the lowest power that gives a clean cut, then adjust. Typical errors include dragging the loop slowly through tissue, using coagulation waveforms to cut, and activating before the loop is in contact or in position. Always check neutral electrode contact for monopolar loops and keep the loop clear of metal instruments during activation. Our guides on cut and coag waveforms and diathermy machine settings explain the options in more detail.

Ask suppliers which loop sizes are held in stock locally, how reusable shafts are reprocessed and how many uses are validated, since these factors drive running costs and downtime.

Next step

If you are equipping a gynaecology or day-surgery unit, Beckfinity can help match generator, loops and smoke evacuation to your procedures. Contact us via our contact page for a consultation.