Menstruation pulls the trigger for inflammation and pain in endometriosis.

Endometriosis is a chronic, hormone-dependent, inflammatory disease, characterized by the presence and growth of endometrial tissue outside the uterine cavity. It affects 5-10% of the female population of reproductive age and is frequently associated with moderate to severe pain, subfertility, and a marked reduction in health-related quality of life. Here, we propose a new pathophysiological concept of endometriosis, summarizing recent findings in one unifying picture. We propose menstruating tissue as the trigger for inflammatory pain in endometriosis through the activation of innate immune cells and peripheral nerve endings. We speculate how innovative treatment modalities beyond hormonal treatment will improve patients' lives.