Resource Library

Endometriosis is a condition in which the tissue that behaves like the cells lining the uterus (endometrium) grows in other areas of the body, causing pain, irregular bleeding, and possible infertility.

The tissue growth (implant) typically occurs in the pelvic area, outside of the uterus, on the ovaries, bowel, rectum, bladder, and the delicate lining of the pelvis. However, the implants can occur in other areas of the body, too.

Each month a woman's ovaries produce hormones that stimulate the cells of the uterine lining (endometrium) to multiply and prepare for a fertilized egg. The lining swells and gets thicker.

If these cells (called endometrial cells) grow outside the uterus, endometriosis results. Unlike cells normally found in the uterus that are shed during menstruation, the ones outside the uterus stay in place. They sometimes bleed a little bit, but they heal and are stimulated again during the next cycle.

This ongoing process leads to symptoms of endometriosis (pain) and can cause scars (adhesions) on the tubes, ovaries, and surrounding structures in the pelvis.

The cause of endometriosis is unknown, but there are a number of theories. One theory is that the endometrial cells loosened during menstruation may "back up" through the fallopian tubes into the pelvis. Once there, they implant and grow in the pelvic or abdominal cavities. This is called retrograde menstruation. This happens in many women, but there may be something different about the immune system in women who develop endometriosis compared to those who do not get the condition.

Endometriosis is a common problem. Sometimes, it may run in the family. Although endometriosis is typically diagnosed between ages 25 - 35, the condition probably begins about the time that regular menstruation begins.

A woman who has a mother or sister with endometriosis is six times more likely to develop endometriosis than women in the general population. Other possible risk factors include:

• Starting menstruation at an early age
• Never having had children
• Frequent menstrual cycles
• Periods that last 7 or more days
• Problems such as a closed hyman, which block the flow of menstrual blood during the period

Pain is the main symptom for women with endometriosis. This can include:

• Painful periods
• Pain in the lower abdomen or pelvic cramps that can be felt for a week or two before menstruation
• Pain in the lower abdomen felt during menstruation (the pain and cramps may be steady and dull or severe)
• Pain during or following sexual intercourse
• Pain with bowel movements
• Pelvic or low back pain that may occur at any time during the menstrual cycle

Note: Often there are no symptoms. In fact, some women with severe cases of endometriosis have no pain at all, whereas some women with mild endometriosis have severe pain.

Tests that are done to diagnose endometriosis include:

• Pelvic exam
• Transvaginal ultrasound
• Pelvic laparoscopy

Hormone therapy and pelvic laparoscopy cannot cure endometriosis. However, it can partially or completely relieve symptoms in many patients for a number of years.

Removing the uterus (hysterectomy), both ovaries and tubes give the best chance of a cure for endometriosis. You may need hormone replacement therapy after your ovaries are removed. Rarely endometriosis can come back, even after a hysterectomy.

Endometriosis may result in infertility, but not in every patient, and especially if the endometriosis is mild. Laparoscopic surgery may help improve fertility. The chance of success depends on the severity of the endometriosis. If the first surgery does not aid in getting pregnant, repeating the laparoscopy is unlikely to help. Patients should consider further infertility treatments.

Endometriosis can lead to problems getting pregnant (infertility). Other complications include:

• Chronic or long-term pelvic pain that interferes with social and work activities
• Large cysts in the pelvis (called endometriomas) that may break open (rupture)

Other complications are rare. In a few cases, endometriosis implants may cause blockages of the gastrointestinal or urinary tracts.

Very rarely, cancer may develop in the areas of endometriosis after menopause.

Call for an appointment with your health care provider if:

• You have symptoms of endometriosis
• Back pain or other symptoms come back after endometriosis is treated

Consider getting screened for endometriosis if your mother or sister has been diagnosed with endometriosis, or if you are unable to become pregnant after trying for 1 year.

Birth control pills may help to prevent or slow down the development of the disease.

Lobo R. Endometriosis: etiology, pathology, diagnosis, management. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap. 19.

Mounsey AL. Diagnosis and management of endometriosis. Am Fam Physician. 2006;74(4):594-600.

Davis L, Kennedy S. Modern combined oral contraceptives for pain associated with endometriosis. Cochrane Database Syst Rev. 2007;(3):CD001019.

Levy BS. The complex nature of chronic pelvic pain. J Fam Pract. 2007;56:S16-S17.

Bulun SE. Endometriosis. N Engl J Med. 2009;360:268-279.

Jacobson TZ, Barlow DH, Koninckx PR, Olive D, Farquhar C. Laparoscopic surgery for subfertility associated with endometriosis. Cochrane Database Syst Rev;2002;(4):CD001398.