Progestogens and endometriosis

In endometriosis, endometrial-like tissue is found most commonly in the peritoneal cavity, ovaries and rectovaginal septum. Endometriosis is characterised by a progesterone resistant endometrium and an immunologically compromised peritoneal microenvironment. The sequelae are infertility, dysmenorrhea, dyspareunia and chronic pelvic pain. Chronic pelvic pain causes disability and distress with a very high economic impact. The main treatment modality is surgery. The most likely mechanism of effect of progestogens is on the inflammatory reaction surrounding endometriotic deposits. However, resistance to progesterone is characteristic in endometriosis, as the ectopic endometrium cannot be decidualised as eutiopic endometrium. Progestogens are indicated for pain relief, bleeding and other symptoms of endometriosis when long-term medication or repeated courses of treatment are indicated. The main advantage of progestogen therapy is the relative lack of major side effects. However, there is little data comparing different progestogens and progestogens have no effect on endometriosis related infertility.