ABSTRACT
Although the definition of endometriosis has not changed over time, our understanding of endometriosis has evolved progressively. It is mandatory therefore to interpret the literature inorder tounderstand which clinical conditions were considered whenatagivenperiodtheword ‘endometriosis’was used. Endometriosis has been defined as endometrial glands and stroma outside the uterus, and this morphologic definition is still the gold standard. At thebeginningof the20thcenturyendometriosiswas introduced as severe lesions, i.e. ovarian ‘chocolate cysts’1 and adenomyosis externa.2-4 In the following years, black puckered lesions in the pelvis found accidentally during surgery were recognized as endometriosis. In the early 1950s, transplantation experiments of endometrium seemed to bring final proof of the pathophysiologic implantation theory of endometriosis, as postulated by Sampson 30 years earlier.1
