In the 1920′s John Sampson of New York proposed that endometriosis resulted from retrograde menstruation. In other words some part of the menstrual loss flows up the Fallopian tubes and on to the surfaces of the pelvic organs rather than out of the body through the cervix. Sampson made many other observations regarding endometriosis in a series of detailed, and scholarly, papers between 1921 and 1929.
Since that time no-one has explained why this disturbance to the menstrual loss, occurs. Others have confirmed that it happens. Doctors see menstrual loss from the Fallopian tubes occasionally during laparoscopic examinations. Specific imaging studies using ultrasound techniques and dynamic magnetic resonance imaging confirm abnormal contractility of the uterus and Fallopian tube in women with endometriosis. Studies of women with chronic pelvic pain, without endometriosis, are less frequent – though we would expect them to show the same effects.
It is now clear that there are abnormal nerves in the lower uterus, cervix, vagina and uterosacral ligaments in women with chronic pelvic pain with, or without, endometriosis. These nerves may cause the abnormal contractility in the lower uterus and Fallopian tubes that will not only interfere with menstruation – but also interfere with transport of egg and sperm when trying to get pregnant.