Endometriosis: a life cycle approach?

To improve the still fragmented understanding of endometriosis, a life cycle approach was adopted that revealed unexpected aspects of the natural history of the disease throughout a woman's life. Three age-related stages of endometriosis are distinguished. In premenarcheal and adolescent endometriosis, 2 types can be distinguished: a classic form that can occur before menarche, and a congenital obstructive form that is caused by uterine anomaly and outflow obstruction. The lesions include superficial peritoneal implants, but adhesions and endometrioma can also occur. It is suggested that premenarcheal and possibly adolescent endometriosis develop by activation of resting stem cells shed at the time of neonatal retrograde uterine bleeding. In the adult, endometriosis can be related to uterine preconditioning by cyclic menstruations acting as a priming mechanism for deep placentation. In adult life, the typical lesions are peritoneal, ovarian, and deep or adenomyotic endometriosis. More recently, endometriosis has been associated with endometrial dysfunction and myometrial junctional zone hyperplasia. These uterine changes can be linked with some major obstetrical syndromes. In postmenopause, endometriosis can develop or be reactivated both in the presence or absence of exogenous estrogens and can spread to a variety of organs and structures causing constrictive lesions.