In endometriosis, tissue similar to the endometrium is found in other areas in the body and acts like tissue in the uterus. It most often appears in places within the pelvis, including the:

• Ovaries
• Fallopian tubes
• Outside of the uterus
• Cul-de-sac (the space behind the uterus)
• Bowel
• Bladder
• Rectum

Endometrial tissue may at-tach to organs in the pelvis or to the peritoneum. It may also be found in other parts of the body, although this is very rare. Endometrial tissue outside the uterus responds to monthly changes in hormones the same way it does inside the uterus It also breaks down and bleeds This bleeding can cause pain especially during your period The breakdown and bleeding of this tissue each month can Rectum cause scar tissue, called adhesions. Sometimes adhesions bind organs together. Adhesions can also cause pain. If blood is trapped in the ovary because of adhesions, it can form an endometrioma (also known as a cyst). No one is certain of the cause of endometriosis. One theory is that blood sometimes backs up and car-ries tissue from inside the uterus into the fallopian tubes during your period. The tissue then travels out of the tubes and attaches to other places. Another theory is that endometrial cells are transported through blood and lymph vessels.

About 7% of women of childbearing age in the United States have endometriosis. It is most common in women in their 30s and 40s, but it can occur anytime in women who menstruate. Endometriosis occurs more often in women who have never had children. Women whose mother, sister, or daughter has had en-dometriosis are more likely to have it. The symptoms of endometriosis often get worse over time. It will progress in more than half of women who are not treated and in 20% of women who are treated. Treatment may help keep the condition from getting worse.