A: The most widely accepted cause of the disease is retrograde menstruation.

One theory suggests that retrograde menstruation - or "reverse menstruation" may be the predominant cause.

However, in some patients, endometrial tissue transplanted by retrograde menstruation may be able to implant and establish itself as endometriosis.

(2) Through observations in laparoscopy, we know that 90 percent of women with normal, unobstructed Fallopian tubes have retrograde menstruation.

The theory of retrograde menstruation as a cause of endometriosis was first proposed by John A. Sampson.

The main theories for the formation of ectopic endometrium are retrograde menstruation, müllerianosis, coelomic metaplasia and transplantation, each further described below.

By the time a correct diagnosis has been made, endometrium and other fluids have filled the uterus and fallopian tubes with results similar to retrograde menstruation resulting in endometriosis.

The theory of retrograde menstruation (also called the implantation theory or transplantation theory) is the most widely accepted theory for the formation of ectopic endometrium in endometriosis.

But women with endometriosis may have a problem with the immune system that may impair this process.1 Menstrual bleeding (which contains endometrial cells) is carried up through the fallopian tubes into the abdomen (retrograde menstruation).

Retrograde menstruation alone is not able to explain all instances of endometriosis, and it needs additional factors such as genetic or immune differences to account for the fact that many women with retrograde menstruation do not have endometriosis.

His theory of 'retrograde menstruation' explains the typical distribution of endometriosis in the pelvis and why women with cervical or vaginal obstruction have a high incidence of endometriosis, it does not, however, provide an answer why some women have endometiosis after hysterectomy or in distant organs.