Histological Depth of Burn with Bipolar Plasma Arc – Is That the Cause for Urethral Sphincter Damage in Bipolar Transurethral Resection of the Prostate?

Abstract

Introduction: The bipolar plasma button is gaining acceptance as a modality to perform endoscopic enucleation of the prostate. The plasma arc during activation of the button electrode extends for a distance beyond the edge of the evaporated area as seen on endoscopy. The extent of tissue affected by the intense heat of the arc is not certain. The histologically measurable depth of burn may have relevance during apical dissection, where thermal spread has been implicated in sphincter injury. Objectives: Our objective was to assess the histological depth of burn in animal tissue using a bipolar button electrode. Materials and Methods: Using a KENTAMED hARTT 400 electrosurgical unit machine, the following cuts were made over three freshly acquired goat liver specimens in a normal saline bath: (a) 280 W single superficial cuts using cutting current, (b) 280 W multiple deep cuts in the same groove using cutting current, and (c) 140 W, 2 s contact with coagulation current. Samples were fixed in neutral buffered formalin and processed paraffin embedded, and sections were stained with hematoxylin and eosin. The extent of thermal effect beyond the evaporated tissue edge was assessed on histopathology by a senior pathologist. Results: The histological depth of injury (involving about 5–6 rows of hepatocytes) did not extend more than 0.5 mm beyond the grossly visible edge of evaporated tissue. Conclusions: We found that the histological depth of burn in animal tissue extended only 0.5 mm beyond the grossly visible edge of the evaporation defect unlikely contributing to sphincter injury.