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What is endometriosis?

Endometriosis is a common, yet poorly understood, disease that can strike women of any socioeconomic class, age or race. It is estimated that between 10 percent and 20 percent of American women of childbearing age have endometriosis. The disease can affect nearly every aspect of a woman's life--her ability to work, her ability to reproduce, and her relationships with her mate, her child, and everyone around her.

The name endometriosis comes from the word "endometrium," the tissue that lines the inside of the uterus. If a woman is not pregnant, this tissue builds up and is shed each month and discharged as menstrual flow at the end of each cycle. In endometriosis, tissue that looks and acts like endometrial tissue is found outside the uterus, usually inside the abdominal cavity. This misplaced tissue acts like it would if it were inside the uterus. However, unlike menstrual fluid from the uterus, which is discharged from the body during menstruation, blood from the misplaced tissue has no place to go. Tissues surrounding the area of endometriosis may become inflamed or swollen, leading to the development of scar tissue. These endometrial tissue sites may develop into what are called "lesions," "implants," "nodules" or "growths." After menopause, the abnormal implants shrink away and the symptoms subside.

What are the symptoms of endometriosis?

Most commonly, the symptoms of endometriosis start years after menstrual periods begin. Over the years, the symptoms tend to gradually increase as the endometriosis areas increase in size.

The most common symptom is pain, especially excessive menstrual cramps (dysmenorrhea), which may be felt in the abdomen or lower back or during or after sexual activity (dyspareunia). Infertility occurs in about 30 percent to 40 percent of women with endometriosis. Rarely, the irritation caused by endometrial implants may progress into infection or abscesses causing pain independent of the menstrual cycle. Endometrial patches may also be tender to the touch or to pressure, and intestinal pain may also result from endometrial patches on the walls of the colon or intestine. The amount of pain is not always related to the severity of the disease. Some women with severe endometriosis have no pain; while others with just a few small growths have incapacitating pain.

Does endometriosis cause endometrial cancer?

Endometrial cancer is very rarely associated with endometriosis, occurring in less than 1 percent of women who have the disease. When it does occur, it is usually found in more advanced patches of endometriosis in older women and the long-term outlook in these unusual cases is reasonably good.

Does endometriosis make you infertile?

Severe endometriosis with extensive scarring and organ damage may affect fertility. It is considered one of the three major causes of female infertility. However, unsuspected or mild endometriosis is a common finding among infertile women and how this type of endometriosis affects fertility is still not clear. While the pregnancy rates for patients with endometriosis remain lower than those of the general population, most patients with endometriosis do not experience fertility problems.

What is the cause of endometriosis?

The cause of endometriosis is still unknown. One theory is that during menstruation some of the menstrual tissue backs up through the fallopian tubes into the abdomen, where it implants and grows. Another theory suggests that endometriosis may be a genetic process or that certain families may have predisposing factors to endometriosis.

How would my health care provider know if I had endometriosis?

Diagnosis of endometriosis begins with a gynecologist evaluating the patient's medical history. A complete physical exam, including a pelvic examination, is also necessary. However, diagnosis of endometriosis is only complete when proven by laparoscopy, a minor surgical procedure in which a laparoscope (a tube with a light in it) is inserted into a small incision in the abdomen. The laparoscope is moved around the abdomen, which has been distended with carbon dioxide gas to make the organs easier to see. The surgeon can then check the condition of the abdominal organs and see the endometrial implants. The laparoscopy will show the locations, extent and size of the growths and will help the patient and her doctor to make better-informed decisions about treatment.

What is the treatment for endometriosis?

While the treatment for endometriosis has varied over the years, doctors now agree that if the symptoms are mild, no further treatment other than medication for pain may be needed. For those patients with mild or minimal endometriosis who wish to become pregnant, doctors are advising that, depending on the age of the patient and the amount of pain associated with the disease, the best course of action is to have a trial period of unprotected intercourse for six months to one year. If pregnancy does not occur within that time, then further treatment may be needed.

For patients not seeking to become pregnant and where a definitive diagnosis of endometriosis by laparoscopy has been made, a physician may suggest hormone suppression treatment. Since this therapy shuts off ovulation, women being treated for endometriosis will not get pregnant during such therapy, although some may elect to become pregnant shortly after therapy is stopped. Depending on the severity of the endometriosis, some women may seek surgical treatment to remove the diseased tissue without risking damage to healthy surrounding tissue. This surgery is called laparotomy and is performed in a hospital under anesthesia.

For more information, contact the following organization:

National Institutes of Health