Monopolar electrosurgery through single-port laparoscopy: a potential hidden hazard for bowel burns.

Background: Surveys indicate that up to 90% of general surgeons and gynecologists use monopolar radiofrequency during laparoscopy and 18% have experienced visceral burns. Monopolar electrosurgery compared with other energy sources is associated with unique characteristics and inherent risks and complications caused by inadvertent direct or capacitive coupling or insulation failure of instruments. These dangers become particularly important with the reemergence of single-port laparoscopy, which requires close proximity and crossing of multiple intraabdominal instruments outside the surgeon's field of view.

Study Objectives: To determine the effects of monopolar electrosurgery on various tissues/organs during simulated single-port laparoscopic surgery in vitro and in vivo.

Design: Simulation in a dry laboratory with fresh sheep liver, pig bowel and bowel in an anesthetized dog (Canadian Classification II-3).

Setting: University-affiliated teaching hospital and animal facilities.

Measurements And Main Results: We used Valleylab Force 2 and FX electrosurgical generators at clinically used power outputs of 40 to 60 watts, and both high- and low-voltage (coagulation and cut) waveforms and commercially-available single-port devices. The effect on tissue was recorded by pictures and video camera and graded visually and histologically with hematoxylin and eosin stains. During activation of any standard monopolar laparoscopic instrument (scissors, coagulating electrode, etc), capacitive coupled currents resulting in visible tissue burn (blanching) caused by other adjacent cold instrument (graspers, etc) including metallic suction-irrigation cannulas and the laparoscope itself were noted. Histopathologic study confirmed transmural thermal damage extending to the mucosa of small bowel, even in the presence of mild serosa blanching. With prolonged activation of the electrosurgical generator, the capacitive coupled corona discharge burned the insulation and caused rapid insulation breakdown of the electrode instrument resulting in direct coupling (sparking, arcing) to adjacent cold instruments and more severe burning to the contacted tissue/organ.

Conclusions: During single-port laparoscopy and use of monopolar radiofrequency, the proximity and crossing of multiple instruments generate capacitive or direct coupled currents, which may cause visceral burns.