The name endometriosis comes from the word endometrium. The endometrium is the tissue that lines the inside of the uterus. This tissue builds up every month and then sheds when a woman has her period. Sometimes tissue that is like endometrial tissue shows up on the outside of the uterus and in other places in the body, and starts to grow. This is called endometriosis.

Endometrial tissue (shown in green) can attach to many of the pelvic organs.

The most common locations for endometrial growths are in the:

• cul-de-sac, or pouch between the uterus and rectum
• ligaments that attach the uterus and cervix to the base of the spine
• ovaries
• surface of the uterus
• bowel
• rectum
• bladder
• lining of the abdominal cavity (peritoneum)

Endometrial growths can develop in places outside the abdomen and pelvis, such as the lung, arm and thigh, although this is rare.

Clumps of endometrial tissue growing outside the uterus may be called nodules, lesions, implants, cysts or growths. Sometimes the cysts are called “chocolate cysts” because they contain old blood and have a distinctive brown colour. Like the tissue in the lining of the uterus, these growths build up each month but cannot shed during a woman’s menstrual cycle. This can cause painful internal bleeding and the formation of scar tissue.

Most women do not even know they have endometriosis because they experience no symptoms, but for many women, the condition causes extremely painful periods and other pain symptoms. Endometriosis may be associated with chronic pelvic pain and the inability to get pregnant.

Symptoms of endometriosis include:

• painful periods
• painful sex
• pain in the lower abdomen and/or lower back
• painful bowel movements
• fatigue
• heavy or irregular bleeding
• nausea/dizziness
• diarrhea/constipation

Approximately 30 to 40 percent of women with endometriosis have trouble getting pregnant.

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