What Causes Endometriosis?
Endometriosis may be caused by retrograde menstruation, coelomic metaplasia, and congenital factors. The immune system may allow endometrial cells to establish themselves in other parts of the body and exposure to dioxin and related environmental toxins may also play a role.
Retrograde menstruation (also known as "reverse menstruation") occurs when blood and endometrial tissue back up into the fallopian tubes and enter the pelvic and abdominal cavities instead of flowing out through the cervix and vagina. Reverse menstruation is common, occuring in about 90 percent of women, and may cause endometriosis.
"Metaplasia" refers to the transformation of one kind of tissue into another. Coelomic metaplasia refers to cells that transform into endometrial cells, perhaps as a result of chronic inflammation or irritation from retrograde menstrual blood.
Endometriosis may be a congenital condition (present at birth). During fetal development, uterine tissue may remain in the pelvis and grow as a result of hormonal influence.