Subcutaneous implantation of pure crystalline estradiol pellets for conception control

Assessment of the contraceptive effectiveness of pure estradiol pellets implanted annually under the skin, thus avoiding the 'first passage phenomenon' through the liver, using a modification of Emperaire and Greenblatt's method.

228 women wishing birth control for 1 year or more were included. 5 pellets of estradiol (25 mg each) were implanted initially. At each subsequent annual treatment, 4 pellets were implanted. Withdrawal bleeding was induced monthly with oral norethindrone acetate 5 mg taken for 7 days. Our experience encompassed 8,136 cycles, or 678 women years. The study obtained approval of the local Ethical Committee.

Annual continuation rates were 51 per 100 women in the second year, 65 in the third, 72 in the fourth and 84 +/- 10.1 annually over the next 6 years. Through 12 years of our study, 2 accidental pregnancies occurred. The annual net cumulative pregnancy rates were 0.44 and 0.48 per 100 women at 1 and 2 years, and reduced to 0.29 at the end of 10 years. Return of fecundity after discontinuing treatment was 53% after 12 months, 81% after 24 months and 89% after 36 months. The mean estradiol levels were 1,413 +/- 161 pmol/l one week following the pellet installation. The mean serum estradiol level of the 43 women who were assayed arbitrarily or a year following last insertion was 1,207 pmol/l (range 462-2,904 pmol/l); 22% had serum estradiol levels <1,000 pmol/l and 6.3% (3 women) had levels >1,750 pmol/l. A total of 28 endometrial biopsies were obtained -19 were proliferative, 6 showed slight simple hyperplasia, and three, benign cystic glandular hyperplasia.

Subcutaneous implantation of pure estradiol pellets offers excellent birth control, has minimal untoward effects, is simple to insert and can serve as a possible alternative for conception control. It could be considered for 3 indications: for women who have completed family planning; for women in older age group (above 35 years) who are approaching the climacteric; and for women at any age, who need prolonged periods of contraception.