Ultrasonic thermal damage during robotic hysterectomy

Application of energy in minimally invasive hysterectomy creates thermal injury which may increase vaginal cuff dehiscence. The purpose of this study was to compare vaginal tissue damage in a swine model between the two power settings of ultrasonic energy. This was an IACUC-approved, prospective, single-blinded study analyzing energy-induced damage to the swine vagina during robotic hysterectomy. Multiple colpotomy transections were performed on 18 animals using robotic ultrasonic energy, the exact same platform used in human surgery. Specimens (n = 72) were analyzed by a veterinary pathologist blinded to the energy source. Thermal injury was microscopically measured. Mean thermal injury (µm) was not statistically different between Max-Setting 5 and Min-Setting 3 (1243 ± 544 vs. 1293 ± 554; 95 % CI -310 to 210, p = 0.66). Time (s) to complete transection was significantly shorter when using Setting 5 (13.00 ± 7.75 vs. 17.92 ± 9.03; 95 % CI -4.92 to -8.88, p = 0.001). The rate of injury (µm/s) for Setting 5 also trended toward being higher (118.98 ± 72.81 vs. 93.03 ± 62.34; 95 % CI -5.91 to 57.81, p = 0.053). In these swine vaginal specimens, energy-induced tissue damage was not statistically different for the two ultrasonic power settings. Max-Setting 5 was faster and trended toward a higher rate of damage; this was balanced by equivalent distance of tissue injury compared with Min-Setting 3. In larger human specimens, the use of Max-Setting 5 may be recommended to decrease surgical time as it is faster and causes an equivalent amount of injury to Min-Setting 3.