Rethinking endometriosis and pelvic pain

Endometriosis is defined as the presence of endometrial glands and stroma outside of the uterine cavity that can lead to pelvic pain and infertility (1). Clinical histories consistent with endometriosis can be found dating back to the 17th and 18th centuries (2). In 1899, Russel first described and illustrated the presence of endometrial tissue within an ovary (3). In 1921, Sampson published his first case series of 23 patients with ovarian endometriomas and posited the theory of retrograde menstruation (4). Endometriosis affects up to 10%-15% of women of reproductive age (1). Despite this prevalence and ongoing research efforts, much about endometriosis remains an enigma, including its variability in symptoms and progression of disease, underlying pain mechanisms, effect on fertility, and response to treatment. After more than one hundred years of experience with endometriosis, why do we understand so little? To move the field forward, perhaps it's time to take a step back, pause, and reconsider critical issues related to endometriosis. What's in a name? In medical school, we are taught the "classic" phenotype of endometriosis - early onset of severe menstrual period pain (dysmenorrhea) that often progresses to include noncyclic pain - as well as the 3 "dys's," i.e., dyschezia (pain when defecating that may be accompanied by changes in frequency of bowel movement), dyspareunia (persistent or recurrent vaginal pain [...]