Those likely to develop endometriosis include people who have never given birth, have close female relatives with the condition, have a past history of pelvic inflammation or uterine abnormalities, or have a condition that restricts the normal flow of menstruation.
Endometriosis usually develops a few years after the first period and can end temporarily with pregnancy. The chances of developing endometriosis usually end with menopause but can be extended with estrogen use.
Endometrium tissue can develop in several areas -- as lesions or growths on the abdomen near or on the ovaries; in the area between the vagina and rectum; in the lining of the pelvic cavity; and on the outer surface of the uterus itself.
It can also be found in the bowel, bladder, vagina, vulva and cervix, in any previous surgical scars, the arm, thigh, lung and other locations.
While the exact cause of endometriosis remains a mystery, there are several theories on how and why the disease develops.
1) Retrograde menstruation – During menstruation, tissue reverses through the fallopian tubes and implants in the abdomen. Because all women experience some form of tissue backup, researchers believe that an immune system disorder or hormonal issue promotes the tissue growth that results in endometriosis. This is sometimes referred to as the trans-tubal migration theory.
2) Lymph/blood system distribution – Endometrial tissue is distributed by the uterus through the blood or lymph system to other parts of the body. This cause is believed to be genetic, which would explain why this disease runs in families.