Menstruation as the pelvic aggressor.

Cumulative evidence supports the concept of retrograde menstruation being a pelvic aggressor as it contributes to both the development of endometriosis and related symptoms such as dysmenorrhoea and infertility. A major problem in studying the association between these entities (retrograde menstruation, endometriosis, dysmenorrhoea and infertility) is the lack of an accurate method to quantify the amount of retrograde menstruation.