Endometrial destruction by hyperthermia - A possible treatment of menorrhagia - An experimental study

Background. Treatment of menorrhagia by heat-destruction of the endometrium, intended to be an alternative to hysterectomy, was investigated in an experimental study. Method. A specially designed catheter (Cavaterm(TM)) with a silicone balloon containing a self-regulating heating element is inserted into the uterus, filled with glycine to a pressure of around 180 mmHg and heated to about 75 degrees C. We investigated the treatment effect in vitro in five extirpated uteri (series A) and in vivo in three patients treated peroperatively just before hysterectomy, temperatures being monitored in the surrounding tissues (series B). In both series we monitored the following variables: heating-power, balloon-pressure, temperature of the heating element (around 85 degrees C) and the temperatures at five locations from top to bottom of the balloon surface. Results. After 30 min in vitro treatment at 75 degrees C, the endometrium was partly destructed, and condensed. Histological examination showed smooth muscle cells to be destroyed to a depth of 2-5 mm close to the endometrium. With in vivo treatment for 30 min at a heating power of about 20 W (resulting in balloon surface temperatures of 58-65 degrees C), the increases in temperature of the surrounding tissue were too small to measure accurately (+/-1 degrees C). Histological examination showed destruction of cells in the corpus uteri to a maximum depth of 8 mm. Conclusion. Findings in in vitro and in vivo experiments suggest that 30 min heating of the endometrium to 58-65 degrees C with an intrauterine silicone balloon filled with a liquid to a pressure of 180 mmHg exerts therapeutic effects on both endometrium and uterine cavity smooth muscle cells without damage to surrounding tissues.