What is endometriosis?

The endometrium is the type of tissue that lines the inside of the uterus. In endometriosis, tissue similar to the endometrium grows outside the uterus. Endometriosis can be a painful condition, especially during menstruation, and endometriosis can impair fertility. Research into the patient experience of this condition has suggested that we redefine endometriosis as a syndrome that includes both these ectopic uterine tissue deposits and the symptoms they cause, since some people with ectopic endometrial tissue don’t experience any symptoms.^[1]