Ethynyl-estradiol (EE-2) retained in blood and endometrium during and after steroidal contraception

Thirty-six women under norgestrel + EE-2 interrupted the medication after 2 to 36 months of regular use. A single venous blood and a single endometrial sample were simultaneously obtained from each subject on different days of the cycle to measure the synthetic estrogen content. Samples were collected during the last month of contraception and in the month after the medication. The EE-2 values (means +/- SE) during and after the "pill" were as follows: endometrial = 90 +/- 18 vs 234 +/- 5 ng/g wet tissue (P less than 0.001), and in blood = 90 +/- 18 vs 234 +/- 32 pg/ml (P less than 0.001). In a hysterectomized woman 30 micrograms of oral EE-2/d/20 d, yielded plasma EE-2 concentrations up to 979 pg/ml, descending to 30 pg/ml under no treatment. The results demonstrate that in intact women, exfoliation of the endometrium after one month of no steroidal ingestion, did not achieve the complete synthetic estrogen elimination from tissue, while blood levels of EE-2 increased during the same period of observation.