The history of endometriosis: identifying the disease.

The history of endometriosis is reviewed in the light of today's clinical and pathological knowledge of this disease. Prior to Sampson's report in 1921, attention was focused on the enclosed type of endometriosis, sited deep in the pelvis and called adenomyosis externa. Sampson's first hypothesis, that rupture of an ovarian endometrioma caused superficial peritoneal endometriosis, was probably changed after this observation that the free, superficial peritoneal implants reacted like eutopic endometrium. These implants were recognized as implants from menstrual blood regurgitated into the pelvic cavity. Adenomyosis externa, ovarian endometrioma and peritoneal endometriosis then came to be regarded as the same disease. In the light of today's knowledge, it may be important to remember this progressive understanding in the nosology of what is now universally called pelvic endometriosis.