Clinical features

Endometrium outside the womb, in various sites of the body goes through the same monthly change as the lining of the womb, causing swelling and bleeding into the body cavity, which can cause inflammation and pain. When it occurs in the ovaries the endometriosis can form cysts (endometrioma). These are also called "chocolate cysts" because of the brown fluid that they contain. They may not cause any symptoms and found incidentally on examinations for other reasons, but they can cause varying degrees of pain, and can be severe if they burst. Fibrous bands of scar tissue, called "adhesions" may form.

Pelvic pain, which feels like period pain, is most common symptom of endometriosis, and is usually felt in the lower abdomen. The symptoms can vary, with some women having no symptoms at all, while others have severe pain. The pain usually occurs around the time of a period, but in some women pelvic pain can be constant. It may be felt on one side of the lower abdomen, in the midline, or bilaterally (both sides). Some women find that sexual intercourse before or during a period is painful. There may also be changes to periods, such as a small loss of blood before the period is due (spotting), irregular, and heavy periods.

Endometriosis affecting the bowel or bladder may cause swelling of the lower abdomen and pain when going to the toilet, or blood in the stools during a period.

Symptoms of endometriosis often disappear during pregnancy or after the menopause.

Amended November 2008