Effects of conjugated estrogens and progestogen in surgically induced endometriosis in oophorectomized rats.

This study aimed to verify whether estrogen replacement alone or associated with progesterone promotes the recurrence of experimental endometriosis in oophorectomized rats. The procedure utilized for endometriosis induction was adapted from the one described by Jones (1984). The rats were castrated three weeks after the induction. Hormonal replacement was started 14 days after the castration and was given for 24 days. One group received estrogen alone, another received estrogen associated with medroxiprogesterone acetate, and a last one received placebo. At the end of this study, the animals who received hormonal medication showed recurrence of the disease. This fact was more evident in the group that received estrogen alone. We concluded that estrogen alone leads to recurrence of endometriosis in oophorectomized rats with surgically induced endometriosis. The association of medroxiprogesterone promotes involutional changes in the implants, and should be added upon the existence of a past history of endometriosis.