Other predisposing factors include previous surgery in which the
uterine lining is touched by surgical instruments. It is hereditary. If your mother or
sister had endometriosis, there is a good chance that you will develop one too.
The most consistent risk factor is severe stress, especially of a
sexual nature. This could be a physical stress or it could be a combination of physical
and emotional distress.
No fewer than 12 theories have been proposed since 1921 to explain how
and why endometriosis occurs. The reflux menstruation theory was developed by John
Sampson, M.D., in 1920. According to this theory, menstrual fluid backs up into the
fallopian tubes and drops into the peritoneal cavity, where endometrial cells implant
themselves and grow. While this theory offers an answer to the question of what causes
endometriosis, it has never been proved. Another popular theory states that endometriosis
is caused when endometrial cells spread to other parts of the body through
blood and lymphatic channels. Still another theory postulates that endometriosis
is in effect a congenital condition.
The "immune defect" theory, is based on the high levels of
antibodies (disease-fighting proteins) found in endometriosis patients' blood, plus
observation of spontaneous development of endometriosis in monkeys and the fact that women
whose close relatives have the disease are at increased risk. In some women a hereditary
tendency toward endometriosis, together with an immune reaction against their own tissues,
might bring on the disease.
Environmental factors may also contribute to endometriosis. Studies have shown that
women who suffer from endometriosis had a higher levels of the pesticide dioxin in their
blood. Eighty percent of female rhesus monkeys exposed to very small amounts of these
chemicals over four years have developed endometriosis. More of the monkeys on the highest
doses had moderate to severe disease than those on the lowest doses. Monkeys not receiving
dioxin did not develop either moderate or severe disease.
A 1992 study done in Germany showed that endometriosis is also
correlated with PCBs. PCBs and dioxin both interfere with the immune system and the
endocrine system. Researchers have postulated that endometriosis is somehow caused by
malfunction of both the immune and endocrine systems.