Principles of medical therapy for endometriosis pain

Summary

Endometriosis essentially consists of patches of endometrioid differentiation of the pelvic mesenchyme. Endometriotic tissue is, like the endometrium itself, dependent on ovarian steroid hormones for support. Endometriosis, like endometrium, proliferates under the action of oestradiol, whereas progesterone and the progestagens put an end to epithelial mitosis, and secretory differentiation of the epithelium follows. When oestradiol, and particularly progesterone, are withdrawn, endometriotic tissue, again like endometrium, breaks down and releases locally and to some extent systemically, a range of important prostanoids and peptides that account for the symptoms we attribute to endometriosis, especially pelvic pain in the form of dysmenorrhoea, dyspareunia and tenderness on palpation. This can happen if bleeding and haemosiderin deposition takes place to produce pigmented stigmata or if, in ‘still-to-be’ pigmented endometriosis (Jansen and Russell, 1986), it does not.