Endometriosis

Endometriosis is a common medical condition where the tissue lining the uterus (the endometrium, from endo, "inside", and metrium, "mother") is found outside of the uterus, typically affecting other organs in the pelvis. The condition can lead to serious health problems, primarily pain and infertility. Endometriosis primarily develops in women of the reproductive age.

Causes

While the exact cause of endometriosis remains unknown, many theories have been presented to explain its development. These concepts do not necessarily exclude each other.

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• Endometriosis is an estrogen-dependent condition, as it is seen during the reproducive years and generally disappears after menopause. In experimental models, estrogen is necessary to induce or maintain endometriosis. Medical therapy is often aimed at lowering estrogen levels to control the disease.
• "Retrograde menstruation", by which some of the menstrual debris of her period flows into her pelvis, may play an important role (John A. Sampson). While most women may have some retrograde menstrual flow, typically their immune system is able to clear the debris and prevents implantation and growth of cells from this occurrence. However, in some patients, endometrial tissue transplanted by retrograde menstruation is able to implant and establish itself as endometriosis. Factors that might cause the tissue to grow in some women, but not in others, need to be elucidated, and some of the possible causes below may provide some explanation, i.e. hereditary factors, toxins, or a compromised immune system. It can be argued that the uninterrupted occurrence of regular menstruation over decades month after month is a modern phenomenon, as in the past women had more frequently menstrual rest due to pregnancy or lacation.
• A competing theory suggests that endometriosis does not represent transplanted endometrium but starts de novo from local stem cells. This process has been referred to as coelomic metaplasia. Triggers of various kind (including menses, toxins, or immune factors) may be necessary to start this process.
• Hereditary factors play a role. It is well recognized that daughters or sisters of patients with endometriosis are at higher risk to develop endometriosis themselves. A specific gene, however, has not been identified. ***new research just identified link***

A recent study (2005) published in the American Journal of Human Genetics found a link between endometriosis and chromosome 10q26.

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http://www.medicine.ox.ac.uk/ndog/oxegene/Papers/ASHG%20%282005%29.pdf

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• It is accepted that in specific patients endometriosis can spread directly. Thus endometriosis has been found in abdominal incisional scars after surgery for endometriosis.
• On rare occasions endometriosis may be transplanted by blood or by the lymphatic system into peripheral organs (i.e. lungs, brain).
• Recent research is focussing on the immune system that may not be able to cope with the cyclic onslaught of retrograde menstrual fluid. In this context there is interest to study relationship to autoimmune disease, allergy reactions, and the impact of toxins.

Another area of research is the search for endometriosis markers. These markers are substances made by or in response to endometriosis that health care providers can measure in the blood or urine. If markers are found, health care providers could diagnose endometriosis by testing a woman's blood or urine, which might reduce the need for surgery. CA 125 is known to be elevated in many patients with endometriosis, but not specifically indicative of endometriosis.

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