Endometriosis refers to the condition in which cells making up the lining of the uterus (the endometrium), break away and grow outside the uterine cavity, implanting themselves in the pelvis. These implants can occur in many locations within the pelvis, including the ovaries, cervix, appendix, bowel, bladder, and ligaments of the uterus.
Like the regular lining of the uterus, these implants respond to hormonal stimulation and can cause bleeding in the pelvic cavity. Unlike normal menstrual bleeding, implant bleeding cannot leave the body through the vaginal opening during menstruation. Instead, blood from the endometrial implants remain trapped in the pelvis where it can cause inflammation, cysts, scar tissue, and other structural damage to the many tissues and organs in this area.
The endometrial implants can assume a variety of shapes and colors. Fibrous tissue often grows around these lesions, giving them a puckered appearance. In advanced cases, adhesions (scar tissue) develop around the implants. The scar tissue can be so dense that it obliterates the normal pelvic structures. Endometrial implants on the ovaries can cause painful ovarian cysts.
Endometriosis is a relatively common problem, affecting as many as five million American women (up to 15 percent of the female population). Women in their 30s and 40s are most likely to have endometriosis. Endometriosis causes chronic pain and damage to the reproductive system, and can hamper childbearing. In fact, 20 to 66 percent of women with endometriosis experience infertility.