Presence of ethynyl-estradiol (EE-2) in blood and endometrium after interrupting steroidal contraception for three months

Serial studies were conducted in five women under norgestrel + EE-2 after interrupting 11-34 months of regular use of the medication. A venous blood and an endometrial sample were simultaneously obtained from each subject between the 22nd and 25th day of the pseudocycle (last month of contraception) and on the same days of the following three cycles under no treatment for the measurement of EE-2 content. Values during and after the first month of no medication were: plasma = 85 +/- 6 versus 218 +/- 36 (pg/ml; P less than 0.001) and endometrium = 93 +/- 10 versus 29 +/- 7 (ng/g wet tissue; P less than 0.001). A decrement of circulating EE-2 from 346 pg/ml in the first month with no medication to 14 pg/ml in the third month off the treatment was observed. The EE-2 endometrial uptake of 93 +/- 10 (last month of steroidal ingestion) decreased to 29 +/- 7, 7 +/- 2 and 4 +/- 0.9 ng/g wet tissue in the following three months of no treatment. In 3/15 instances after interrupting contraception, circulating EE-2 was below the detection limit of the assay, while endometrial EE-2 uptake was in the range of 3-19 ng/g wet tissue. These data confirm our apparent controversial report that EE-2 plasma levels increased during the first month after interrupting medication and support the presence of the exogenous estrogen in plasma and endometrium after interrupting the steroidal contraceptive for three months.