Current facts constituting an understanding of the nature of adenomyosis.

Adenomyosis seems to be the most widespread coexistent pathology included under the umbrella of common benign disorders of the human uterus. The incidence of adenomyosis is under discussion since different imaging criteria are used. In the majority of cases, prevalence is determined among women with uterine fibroids and endometriosis or severe gynecological symptoms. This common benign pathology is asymptomatic in 1/3 of cases. Up to 50% of women with infertility are affected by adenomyosis. It seems to be an important risk factor for spontaneous pre-term delivery and pre-term premature rupture of the membranes. Nowadays, the etiology of adenomyosis is still unclear and requires deeper investigation. This review summarizes the aspects of prevalence, co-existence, risk factors, classification, mechanisms of pathogenesis, genes and immunological features, main histological features, animal models, and clinical manifestation of adenomyosis. It might facilitate understanding of the independent nature of such a dual enigma as adenomyosis.