Electrosurgical hot biopsy forceps coagulation: more (intensity) is less (complications)

I have read with interest the ESGE guideline on the use of electrosurgical units [1] and would like to make some comments.

Hot biopsy forceps polypectomy (HBFP) is frequently criticized for its high frequency of complications. In fact, the main problem lies in an erroneous understanding of the effect of high frequency current (HFC) [1].

Impedance, it should be noted, is the appropriate concept to use with regard to HFC, and not resistance [2].

Desiccation induced by coagulation increases impedance, implying diminished heating beyond the immediate area and re-routing of current through non-desiccated pathways, especially if the current is applied in successive short bursts [3]. This leads to an homogeneous coagulation of the base of the polyps.

It is well known to surgeons that high intensity of application leads to bad coagulation, as the steep increase of impedance limits the depth of the effect [2] [3]. On the contrary, a good, deep, efficient coagulation requires a lower setting and a longer time, according to the thickness of the grasped tissues [2] [3].

However, for small polyps, the task is the destruction of mucosa, which is superficial and lacks large vessels, rather than artery-rich submucosa.

The popular but erroneous recommendation to use the lowest power setting possible is dangerous because this method is safe only if the application time is short [3], and this has been progressively forgotten [1] [2] [3]. Short duration – low intensity implies a low total energy transfer to tissues, which probably explains the high failure rate for HBFP. On the other hand, if enough energy is to be transferred, a low intensity implies a longer application time and, therefore, deep heating, which would account for occurrences of perforation and also of late bleeding [3] [4]. This is especially dangerous in the case of a thin wall. As a matter of fact, the risk of late bleeding is proportional to the number of needlessly coagulated arteries.

Delivery of the same total amount of energy has very different effects, according to the duration of that delivery [2] [3].

In this case, misplaced caution leads to less safety for the patient.

• References

• 1 Rey JF, Beilenhoff U, Neumann CF. European Society of Gastrointestinal Endoscopy (ESGE) et al. Guideline: the use of electrosurgical units. Endoscopy 2010; 42: 764-771
• 2 Morris ML, Tucker RD, Baron TH et al. Electrosurgery in gastrointestinal endoscopy: principles to practice. Am J Gastroenterol 2009; 104: 1563-1574
• 3 Curtiss LE. High frequency currents in endoscopy: a review of principles and precautions. Gastrointest Endosc 1973; 20: 9-12
• 4 Maroy B, Moullot P. High intensity-low duration “Hot biopsy” forceps coagulation: a safe method. Internet J Surg 2004; 5 (2)