Pathogenesis of endometriosis: Look no further than John Sampson.

Rather than consider endometriosis as an enigmatic disease, reading John Sampson's two theories/mechanisms explains virtually all cases affecting the female. It is true that Sampson's most recent publication, in 1940, which talks about retrograde menstruation via the fallopian tubes, clearly fails to explain many types of endometriosis, particularly that located in extra-pelvic sites. However, his earlier publications of 1911 and 1912, on radiographic studies of hysterectomy specimens that had been injected with various gelatin/bismuth/pigment mixtures examining the unique uterine vasculature, were more important. These studies enabled him to describe 'the escape of foreign material from the uterine cavity into the uterine veins' in 1918 and subsequently to demonstrate metastatic or embolic endometriosis in the first of his two important publications in 1927. Later in that same year, in response to 'academic banter' from other historic gynaecologists, he published a second article that indicated his studies had been redirected to explore the retrograde tubal menstruation idea; this required undertaking his hysterectomies during menses. That work led to his 1940 presentation at the invitation of The American College of Obstetricians and Gynecologists to focus on the second theory/mechanism of endometriosis. This appears to have caused his more important first theory/mechanism to have been forgotten.