Depth of endometrial coagulation with the urologic resectoscope

There is growing interest in using the urologic resectoscope for endometrial ablation, but the actual depth of tissue destruction is unknown. A preliminary in vitro study measured the depth of visible coagulation produced when various waveforms of high-frequency current were applied to tissue using the "rollerball" electrode of the resectoscope. Tissue necrosis caused by high-frequency electrical energy is not immediately apparent: several days must elapse before the true extent of the damage can be seen. To study it, the uterus from a woman who was planning to undergo a hysterectomy was treated with the resectoscope four days prior to surgery. The depth of tissue destruction caused by 19 and 59 W of "cutting" current and by 28 and 57 W of "coagulating" current was 1.5, 2.7, 6.1 and 1.8 mm, respectively. A second patient underwent a hysterectomy 48 hours after resectoscopic endometrial ablation. There was no endometrium remaining, and coagulation extended 2-3 mm into the myometrium. Visual effects on the surface do not predict actual tissue destruction, so further in vivo studies will be necessary in order to obtain consistent clinical results.