Infertility

Endometrial tissue also may grow in the abdominal area or, more rarely, travel far from the pelvic region into the lungs, skin and other regions of the body. No matter where it goes, however, endometrial tissue continues to respond to hormonal signals--specifically estrogen--from the ovaries each month telling it to grow. Estrogen is the hormone that causes your uterine lining to thicken each month. When estrogen level drops, the lining is expelled from your vagina (you get your period). But unlike the tissue lining the uterus, which leaves your body during menstruation, endometriosis tissue is trapped in the pelvic cavity. With no place to go, the tissue bleeds. Your body tries to stop the bleeding through inflammation, a process that can lead to the formation of scar tissue, also called adhesions. This inflammation and the resulting scar tissue may cause pain and other symptoms.
Recent research also finds that this misplaced endometrial tissue may develop its own nerve supply to communicate with the brain, one reason for the condition's severe pain and the other chronic pain conditions so many women with endometriosis also suffer from.
The type and intensity of symptoms range from completely disabling to mild. Sometimes, there aren't any symptoms.
If your endometriosis results in scarring of the reproductive organs, it may affect your ability to get pregnant. In fact, 35 to50 percent of women with the condition have endometriosis have difficulty getting pregnant. Even mild endometriosis can result in infertility.
Researchers don't know what causes endometriosis, but many theories exist. One suggests that retrograde menstruation--or "reverse menstruation"--may be the main cause. In this condition, menstrual blood doesn't flow out of the cervix (the opening of the uterus to the vagina), but, instead, is pushed backward out of the uterus through the fallopian tubes into the pelvic cavity.
But because most women experience some amount of retrograde menstruation without developing endometriosis, researchers believe something else may contribute to its development.
For example, endometriosis could be an immune system problem or hormonal imbalance that enables the endometrial tissue to take root and grow after it is pushed out of the uterus.
Other researchers believe that in some women, certain abdominal cells mistakenly turn into endometrial cells. These same cells are the ones responsible for the growth of a woman's reproductive organs in the embryonic stage. It's believed that something in the woman's genetic makeup or something she's exposed to in the environment in later life changes those cells so they turn into endometrial tissue outside the uterus. There's also some thinking that damage to cells that line the pelvis from a previous infection can lead to endometriosis.
Some studies also show that environmental factors may play a role in the development of endometriosis. Toxins in the environment seem to affect reproductive hormones and immune system responses, but this theory has not been proven and is controversial in the medical community.
Other researchers believe the endometrium itself is abnormal, which allows the tissue to break away and attach elsewhere in the body.
Endometriosis may also be a genetic condition, with studies finding a 5 to 7 percent increase in risk if your mother or sister had the disorder. Research also indicates that daughters of women who took the drug diethylstilbestrol (DES) between 1938 and 1971 to prevent miscarriage have an increased risk of endometriosis.