Interstitial cystitis (IC) and endometriosis have been dubbed the “evil twins.” Like IC, endometriosis affects girls and women. Also like IC, the cause of endometriosis is not known with certainty, but a number of theories have been advanced.

In “endo,” as it is called, tissue from the inner lining of the uterus (endometrium) is found outside the uterus, in other areas of the body. In these locations outside the uterus, the endometrial tissue develops into what are called “nodules,” “tumors,” “lesions,” “implants,” or “growths.” These growths can cause pain, infertility, and other problems.

The most common locations of endometrial growths are in the abdomen—involving the ovaries, the fallopian tubes, the ligaments supporting the uterus, the perineum (area between the vagina and the rectum), the outer surface of the uterus, and the lining of the pelvic cavity. Sometimes the growths are also found in abdominal surgery scars, on the intestines or in the rectum, or on the bladder, vagina, cervix, or vulva. Endometrial growths have also been found outside the abdomen, in the lungs, arms, thighs, and other locations, but this is not common. Like the lining of the uterus, endometrial growths usually respond to the hormones of the menstrual cycle. They build up tissue each month and then break down. The result is internal bleeding, degeneration of the blood and tissue shed from the growths, inflammation of the surrounding areas, and formation of scar tissue (adhesions).

Endometriosis research has shown that environmental toxins such as dioxin and PCBs, which act like hormones in the body and damage the immune system, can cause endometriosis.

For the latest information about endometriosis, visit the Endometriosis Association website.

Revised Wednesday, March 25th, 2015