Effect of low dose endometrial after-loading irradiation upon the hypophysis-ovarian axis.

Endometrial inactivation by irradiation, while simultaneously preserving the ovarian function is sometimes clinically indicated. We have found that after 1100 cGy (rad) the ovarian function remains intact, yet endometrial inactivation is unsatisfactory. Therefore, four premenopausal subjects, with clinical indications for eliminating disturbing uterine bleedings, received each an endometrial dose of 1600 cGy by using a Cathetron afterloading unit. When pre- and post-treatment cycles were compared, the circulating gonadotrophin and estrogen levels were unchanged in three subjects. Nine to 12 weeks after the treatments there were no signs of ovulation and the gonadotrophin levels were generally increased. None of the subjects had experienced any bleedings. We conclude that an endometrial dose of 1600 cGy is effective in inactivating endometrium, but may also lead to an impaired ovarian function and to a premature menopause.