ENDOMETRIAL ABLATION WITH A VAPORIZING ELECTRODE - I - EVALUATION OF IN-VIVO EFFECTS

Background To evaluate histologically and histochemically the physical and thermal effects of a vaporizing electrode as compared with a stan dard cutting loop in the performance of endometrial ablation. Methods. Operative hysteroscopy was performed on 20 menorrhagic patients immed iately before hysterectomy. Part of the posterior uterine wall was tre ated with a cylindrical, grooved, vaporizing electrode and undamped cu rrent set at 200 watts, and part with a standard cutting loop and unda mped current set at 100 watts. A mucosal strip of about 1 cm width was left intact between the two treatment areas. Specimens underwent hist ologic examination after hematoxylin and eosin staining and histochemi cal assessment of thermal injury was based on detection of the respira tory enzyme dihydronicotinamide adenine dinucleotide diaphorase. Resul ts. The mean (standard deviation) endometrial thickness as determined on the untreated area of the posterior uterine wall was 1.08 (0.36) mm . The mean depth of furrows was 3.10 (0.90) mm with the use of the vap orizing electrode and 3.41 (1.11) mm after passage of the cutting loop . Corresponding values when thermal necrosis beneath the ablated area was assessed by the dihydronicotinamide adenine dinucleotide diaphoras e technique were, respectively, 1.80 (0.40) mm and 0.41 (0.20) mm (mea n difference, 1.39 mm; 95% confidence interval, 1.19 to 1.59; p<0.001, Mann-Whitney U test). Conclusions. A vaporizing electrode and a stand ard cutting loop obtained a similar degree of endomyometrial ablation. However, the depth of the thermal effect of the former electrode was significantly greater. Clinical studies are warranted, also considerin g the potential limitation of fluid absorption and menorragia recurren ce when a vaporizing electrode is used.