Endoscopic electrosurgery

Preparation

Be aware of metal jewellery or metalwork
Bowel prep - methane gas (which can be associated with mannitol preparations) can explode

Functions: resect, cut, coagulate mucosal lesions
Hot polypectomy snare, or hot biopsy forceps, or monopolar EMR knives
Hot polypectomy:
- Use either modulated low-voltage (blended) or modulated high-voltage (coag). Pure cutting has the highest risk of post-polypectomy bleeding. Coag has a higher risk of delayed bleed, while blended has a higher risk of immediate bleed.
- Some people use coag to blanch the tissue followed by blended to pull through
- Can also do saline lift and tenting the mucosa at the base of the polyp.
- Don't allow the snare to be tightened too quickly

Radiofrequency array for ablation of oesophageal mucosa, and multipolar electrocoagulation probe (gold probe)

Achieves superficial coagulation of the GI mucosa without deeper thermal injury
Good for ablating AVMs and radiation proctitis
Thin-walled areas - 20W modulated high voltage is usually sufficient
Thick-walled areas - 40-60W may be used
Adjust effect by modulating flow rate of argon and the configuration of the APC probe
Evacuate the argon gas intermittently throughout the procedure to prevent overdistension

Perforation
- Related to thickness of wall - be very careful in caecum and duodenum, while stomach and rectum are much thicker
- Current density is highest at the base of the polyp - if broad-based, it requires more energy to cut, and full-thickness injury is more likely
- Saline lift can buffer the muscularis propria from thermal energy
- The smallest snare and lowest power settings should be used
Direct coupling
- Can occur with failure to fully push instrument out of channel of scope
- Also when a large polyp rests against the opposite wall - prevent this by jiggling the snare to shift the focus of the polyp around