Effects of subcutaneous oestradiol implants on ovarian activity

The effects of subcutaneous oestradiol implants on ovarian activity were investigated in 14 ovulating premenopausal women. Treatment with either 100 mg or 150 mg oestradiol was combined with cyclical oral norethisterone from days 20 to 26 of the cycle to ensure regular withdrawal periods and prevent endometrial hyperplasia. Ovarian function was monitored by regular pelvic ultrasonography and urinalysis over a period of nine cycles. During the first three cycles after hormone implantation, follicular development continued in almost half the study group, but only one of the women in each treatment group showed signs of follicular rupture and luteinization. By the sixth cycle, over half the women given the lower dose of oestradiol were developing follicles, including a large functional cyst in one, but none of them ovulated. A further implant given early in the seventh cycle was associated with ovarian suppression in all cases. Both doses of implant elevated the excretion of oestrone-3-glucuronide compared to pretreatment. The contraceptive and therapeutic implications of these results are discussed.