Endometriosis is a painful condition in which the endometrium (tissue normally found on the inside surface of the uterine wall) is found outside the uterus. The expelled tissue cells migrate to different areas of the body, where they implant themselves and grow, causing pain, infertility and other health problems. These abnormal tissue growths can take the form of nodules, lesions, cysts or other growths.

Why Does It Happen?

Every month, the female body prepares for a possible pregnancy by stimulating normal endometrial tissue growth with female hormones. If conception does not occur, this endometrial lining is shed, which starts the normal menstrual cycle. When a person suffers from endometriosis, the uterus continues its monthly function, while the ectopic (outside the uterus) endometrial tissue that has implanted elsewhere also responds to hormone fluctuations -- swelling, thickening and bleeding at the same time.

Unlike normal endometrial lining, this tissue and bleeding has nowhere to go -- so it remains in the body and causes inflammation in the surrounding tissue, causing scar tissue and adhesions to form. It also creates a dense, fibrous tissue that can weave itself among the pelvic organs, tying them together and interfering with normal organ function. Typically, the affected organs include the ovaries, the muscle tissue around the uterus, the fallopian tubes and the lining of the pelvic cavity.

Less commonly, this tissue can spread to other parts of the body, including the gastrointestinal system, and rarely, the urinary tract and lower genital tract. At times, the lungs and limbs can be affected.

Risk Factors for Endometriosis

While the exact trigger for endometriosis is unknown, researchers believe that a combination of genetics, a dysfunctional immune system, hormones and environmental factors may contribute to its onset. According to the Endometriosis Foundation, a family history of endometriosis increases a woman’s risk of developing endometriosis herself by seven times.