In vitro studies of uterine electrosurgery.

This study investigated electrosurgical techniques in vitro with emphasis on the tissue effects and heat transfer through full-thickness blocks of excised uterine tissue. Uterine morphometry was also examined. The 7-mm cutting resection loop was associated with a surrounding zone of thermal necrosis between 1.07-1.40 mm. There was no variation in this zone when power was altered, but a statistically significant increase was demonstrated with duration of exposure. A depth of destruction of 3.24-3.49 mm was possible with the desiccating coagulation technique, but fulguration achieved a depth of only 1.70-1.78 mm. A greater tissue effect was demonstrated as time intervals were increased. There was a fall-off in the measured rise in temperature with distance; at 4 mm from the active electrode, a mean rise of 4.5C was noted, whereas at 12 mm the mean temperature rise was 3.9C. There was a statistically significant increase in the mean temperature as power output in the cutting mode was increased. At 180 W, the mean rise was 2.0C but by 260 W, it was 3.9C. When the time interval was increased and the power held constant (220 W), a mean rise of 2.5C was recorded at 1 second, compared with 4.6C at 5 seconds, achieving statistical significance. Power increments in the coagulating mode did not alter the temperature profile, but increasing duration of exposure was associated with a significant rise in mean temperature (from 0.8 to 4.6C). A stepwise increase in the baseline temperature was noted with repetitive insults. The mean myometrial thickness of the anterior and posterior walls measured 1.8 and 1.9 cm, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)