Distribution of endometriotic lesions in endometriosis stage IV supports the menstrual reflux theory and requires specific preoperative assessment and therapy.

A detailed picture of the prevalence and distribution of abdomino-pelvic endometriosis in more that 1,500 cases of endometriosis stage IV is presented. A great prevalence of endometriotic localizations in the posterior pelvic compartment compared to the other quadrants with more frequently observed lesions on the left part of the pelvis supports the menstrual reflux theory. The extent of anatomical sites suggests the opportunity to plan a proper preoperative instrumental study for patients with clinical suspect of severe endometriosis possibly to set a multidisciplinary clinical or surgical management.