An In-Vivo Evaluation of the Correlation Between Histologic and Visually Estimated Zones of Tissue Injury Created with Monopolar Electrosurgery

It has been postulated that laparoscopic electrosurgery may be a less predictable surgical method than lasers and substantial tissue injury may occur unbeknownst to the surgeon. We proposed to evaluate the correlation of histologic injury to visual estimated injury in a porcine model undergoing laparoscopic electrosurgery. A 25 kg female pig underwent laparoscopy. Using monopolar scissors, "touch cuts" were performed to create a peritoneal defect. Progressive increases in current density where achieved by increasing the pre-calibrated wattage of a Valley Lab Force 2 generator. Both pure cutting and coagulation waveforms were used. An estimate of lateral damage was obtained by using a calibrated probe. At laparotomy, these tissue samples were individually extracted en-bloc, pinned flat and placed in formalin. Multiple sections were taken from each block and stained. A pathologist who was blinded to power settings evaluated the amount of thermal destruction. Thirty evaluable peritoneal sections were multiply examined by the blinded pathologist. A significant correlation was found between the visual estimation of injury and the histologic grading of tissue damage. (Pearson's Correlation Coefficient=0.42, P<0.02). These findings suggest that visual estimation of laparoscopic tissue injury is correlated to the actual histologic tissue damage. These data may aid the laparoscopic surgeon in evaluating the efficacy of the power settings and the need for modification during the operative procedure rather than retrospectively in the pathology laboratory.