Endometriosis and adenomyosis in the crosshair: variants of one disorder or fortuitous coincidence.

Adenomyosis and endometriosis share a common origin as both of them result from the development of endometrial tissue outside the endometrium. Despite this, the 2 disorders were until recently considered as 2 different entities notably, because of their different epidemiology. Today, however, new findings regarding core similarities in pathophysiology and endometrial receptivity - not altered in assisted reproductive technology when using frozen embryo transfers - tend to reunite these 2 ailments as variants of 1 disorder.