Controlling endometriosis with hormone therapy may be a good idea for some women, as the female sex hormone estrogen certainly fuels endometriosis symptoms. That being said, some research is also suggesting that estrogen may not be the only problem. Some theories suggest that due to the fact that certain changes can be present in the immune system cells in endometriosis sufferers, endometriosis may be caused by a malfunctioning immune system.

Almost all women experience retrograde menstruation. This is when endometrial tissue moves backwards into the abdomen via the fallopian tubes during menstruation. However, despite this fact, usually less than 10% of menstruating women develop endometriosis. This has lead many researchers to believe the theory that endometriosis is actually caused by a faulty immune system that allows endometriosis to develop outside the uterus following retrograde menstruation.

Those who think a malfunctioning immune system may be the cause of endometriosis, believe that the immune system fails to detect and eliminate endometrial tissue developing outside the uterus. Unlike the immune system of the average women - which finds and destroys the endometrial tissue caused by retrograde menstruation - the immune system of women with endometriosis appears to be less active, and even defective, when it comes to the removal of these cells.

Researchers are not exactly sure why this happens. Some believe that women with endometriosis have an insufficient amount of NK (natural killer) cells, which are the part of the immune system responsible for detecting foreign invaders. Without these NK cells, the immune system is weakened and may not be able to stop or recognize endometrial tissue, allowing it to invade and develop.

Others believe that the immune system of endometriosis sufferers may already be overwhelmed in dealing with other problems such as allergies or infections. Still, some think that perhaps the burden of actually fighting the development of endometriosis, overstresses the immune system making it less effective in managing the disorder.

Certain research is also considering the link between autoimmune disorders and endometriosis. Autoimmune disorders are a malfunctioning of the immune system that causes the body to attack its own tissue. Recent studies have revealed that immune system disorders are more common among women with endometriosis than those without the condition.

Researchers are discovering through studies that women with endometriosis are more likely to have: