Endometrial histology during intermittent intranasal luteinizing hormone-releasing hormone (LH-RH) agonist sequentially combined with an oral progestogen as an antiovulatory contraceptive approach.

Endometrial biopsies were performed in four groups of six or seven women treated for periods of 14 or 21 days with 200 micrograms twice daily or 400 micrograms once daily of intranasal Buserelin acetate. Five milligrams of medroxyprogesterone acetate (MPA) was taken orally twice daily on days 15 to 21. A medication-free week followed each treatment period. Between days 12 and 15 of the first treatment cycle, a proliferative endometrium was described in 16 out of 24 biopsies (66%). In 8 specimens (33%), early secretory changes were related to an early and/or short-lived rise in serum progesterone (P). At the end of the fourth treatment cycle, advanced maturation (days 23 to 28) was observed mainly in the 14-day schedules where serum estradiol (E2) was stimulated in or above the normal range of control cycles. Early to midluteal phase dating (days 16 to 22) was described mainly in the 21-day schedules. There was no P elevation in these groups. Five biopsies showing only proliferative tissue were associated with low levels of E2 mainly in the 400 micrograms/day group. The regimen capable of maintaining E2 in the low physiologic range (200 micrograms/12 hours X 21 days) was associated with incomplete secretory changes of the endometrium. A longer period of progestogen administration should produce a more complete maturation of the endometrium.