THE HISTOLOGY AND STRENGTH OF LAPAROSCOPIC UTERINE INCISIONS MADE WITH MONOPOLAR, PLASMA KINETIC, ULTRASONIC, AND LASER ENERGY SOURCES IN THE PORCINE MODEL

Tristi W. Muir, MD, Mohamed Bedaiwy, MD, Jennifer Brainard, MD, Jeffrey Goldberg, MD, Sarah Worley, MS, Tommaso Falcone, MD Cleveland Clinic Foundation, Cleveland, Ohio

   Objective: To examine the integrity of a hysterotomy scar produced by laparoscopic energy sources.

   Materials and Methods: Three pigs were assigned to each of five study groups: control (hysterotomy produced by laparoscopic scissors without energy), monopolar (monopolar hook), plasma kinetic (plasma kinetic needle), ultrasonic (ultrasonic shears), and carbon dioxide laser. Each pig underwent bilateral three-centimeter laparoscopic hysterotomy incisions in the proximal uterine horns with the energy source directed by their study group. These incisions were closed laparoscopically with delayed-absorbable suture. Following a 12-week recovery period, the animals underwent a laparotomy. The presence of uterine fistulas and a qualitative assessment of adhesions (1= mild, 2= moderate, 3= severe) were recorded. To determine the ability of the scar to withstand distention, the endometrial cavity of the uterine horns was inflated to 750 mmHg; the incision was documented to remain intact or burst. Both uterine horns of each porcine hysterectomy specimen were examined grossly and the pr! esences of a scar, perforation, serosal adhesions, or serosal hemorrhage were recorded. Serial cross-sections at 3-mm intervals along the entire length of the scar, as well as the flanking grossly normal regions were entirely submitted for histologic evaluation. The largest cross-sectional area of each fibrous scar at its midpoint was measured from the microscopic slide using a micrometer. A Movat pentachrome stain was used in selected cases to facilitate differentiation of fibrous tissue from myometrial smooth muscle. Groups were compared on adhesion severity using the Kruskal-Wallis test with Dunn’s multiple comparison procedure. Groups were compared on presence of fistulas and bursting using generalized estimating equations (GEE) methods. A Bonferroni correction to the significance criteria was used when multiple pairwise group comparisons were performed; an overall significance level of 0.1 was used because this correction is conservative. The significance level of each pa! irwise comparison was then 0.01.

   Results: There was no evidence of an overall difference between groups on adhesion scored (Kruskal-Wallis test, p=0.054) There were no significant pairwise group differences at the 0.01 level. However, in comparing the monopolar group (mean adhesion score- 2.7/3) with the ultrasonic group (mean adhesion score- 1/3) the pairwise group difference was 0.017 (close to achieving a significant difference). Fistulas were present in the control and the plasma kinetic groups; therefore an overall p-value or pairwise comparison was not possible. There was no evidence of an overall difference between groups on probability of bursting (GEE p= 0.12). There were no significant pairwise group differences at the 0.01 level. There were no significant differences in the mean cross-sectional areas of scar formation: monopolar- 1.67mm, plasma kinetic- 3.68mm, ultrasonic- 1.7mm, and carbon dioxide laser- 3mm.

   Conclusions: There are no significant differences in the integrity or histology of the healed porcine hysterotomy scar produced by the variety of different laparoscopic energy sources used in this pilot study. There was a trend toward more severe adhesions following a hysterotomy with monopolar energy when compared to ultrasonic energy.