Endometriosis Patient Information Fact Sheet

What is endometriosis?
The medical term for the lining of the womb (uterus) is the endometrium. The cells that make up the endometrium are responsive to hormonal changes that occur throughout the menstrual cycle. These changes cause the lining of the womb to thicken in preparation for a fertilized egg. If fertilization does not occur, the lining is then shed in the form of a monthly period. In women with endometriosis, some of the specialized cells that make up the endometrium are also found outside the womb. The cells outside the womb react to hormonal changes in the same way as those inside the womb. However, when the cells outside the womb break down and bleed they remain inside the body, where they can cause considerable pain and discomfort. They can also cause the formation of scar tissue.

The severity of endometriosis varies depending on where the extra cells occur. The cells can grow anywhere in the body, but are usually found within the pelvis; for example, within the fallopian tubes, ovaries, bladder, or bowel. It is estimated that endometriosis affects at least 6.3 million women and girls in the U.S.

What causes endometriosis?
It is not known what causes the growth of the extra endometrial cells, and currently there is no cure for the condition. However, there are a number of treatments available that can help manage the symptoms.

What are the symptoms of endometriosis?
Severe pain may be experienced during periods as a result of bleeding outside the womb. Pain may also be experienced at the time of ovulation or during sexual intercourse. Periods may be heavy (sometimes with clots) or prolonged. Endometriosis may cause the fallopian tubes to become blocked. This can prevent the passage of eggs from the ovaries and lead to fertility problems. Endometriosis is often diagnosed during investigations into infertility.

What tests confirm a diagnosis of endometriosis?
Endometriosis is usually diagnosed using a procedure called a laparoscopy. This is a minor operation that may be carried out as outpatient surgery. A laparoscope, a small fiber-optic tube that transmits images to a video monitor, is passed into the pelvis via a tiny incision at the navel. This enables the doctor to view inside the pelvis and look for the presence of the extra cells.