What is endometriosis? Endometriosis is a disease where tissue similar to that which lines the uterus (the endometrium) grows abnormally, outside of the uterus. It affects 1 in 10 born with women's reproductive organs - not just those who identify as a woman. This can cause extreme pain, growths, nodules and other complications. Because of its growth patterns, it can impact other areas in the body, making it more than a reproductive issue. It can surround other organs, create lumps of tissue that impacts organs, and other common problems. Most commonly, it causes extreme pain during menstruation, or outside of...