Endometriosis
A condition where endometrial-like tissue grows outside the uterus, causing pain and infertility (affecting approximately 10% of reproductive-age women). GnRH agonists (nafarelin, goserelin, leuprolide) and antagonists (elagolix) suppress oestrogen to reduce endometrial tissue activity.
Technical Context
Endometriosis affects approximately 10% of reproductive-age women (approximately 190 million globally). Pathophysiology: endometrial-like tissue outside the uterus (ovaries, peritoneum, rectovaginal septum, rarely extrapelvic) responds to cyclical oestrogen → proliferation, inflammation, fibrosis, adhesion formation → chronic pelvic pain, dysmenorrhoea, dyspareunia, and infertility. Diagnosis: definitive by laparoscopy with histological confirmation (though empirical treatment is increasingly accepted). Hormonal management aims to suppress oestrogen: combined oral contraceptives (first-line), progestins, GnRH agonists (nafarelin nasal spray, goserelin implant, leuprolide depot — effective but cause menopausal symptoms and bone loss, limiting use to 6-12 months; add-back therapy with low-dose HRT mitigates these effects), and oral GnRH antagonists (elagolix — partial oestrogen suppression, dose-dependent, with lower bone loss risk than agonists due to incomplete suppression). Surgery for visible implants/endometriomas is complementary.