Endometriosis (pronounced end-oh-mee-tree-oh-sis) is a painful, chronic and sometimes debilitating gynaecological disease which affects millions of women worldwide.

It occurs when tissue similar to that which lines the uterus (called endometrium) is found growing outside of the womb, usually in the pelvis (although it can be found anywhere in the body), and develops in to growths or lesions.

Endometriosis is most commonly found on or around

:: ovaries
:: fallopian tubes
:: lining of the pelvic cavity
:: ligaments supporting the womb
:: the area between the vagina and rectum
:: vagina
:: vulva
:: bowel
:: bladder
:: existing scars from previous operations
:: intestines
:: pouch of Douglas
:: outer surface of the uterus
:: abdominal cavity
:: uterus

Less commonly (and relatively rarely) it can be found on or around
:: diaphragm
:: lungs
:: kidneys
:: liver
:: nose
:: ears
:: eyes
:: skin
:: spine
:: joints and muscles of the limbs
:: brain

Endometrial tissue can also grow in the muscle layers of the wall of the womb (adenomyosis).

Every month, a woman's body goes through hormonal changes. They naturally release hormones which cause the lining of the womb to increase in preparation for a fertilised egg. If pregnancy does not occur, this lining will break down and bleed. This blood is then released from the body as a menstrual bleed - or a 'period'.

Endometriosis cells react in the same way - except these cells are located outside of the womb. During a woman's monthly cycle, hormones stimulate the endometriosis, causing it to grow, then break down and bleed. This internal bleeding, unlike a period, has no way of leaving the body and results in a build up of inflammation and scarring.

The inflammation can cause various organs such as the bowl or bladder and other pelvic organs to become matted together in a web of scar tissue (called adhesion's). These can cause chronic pain and may interfere with the normal function of the bowel, bladder, ovaries or fallopian tubes, and can sometimes cause infertility.

Endometrial tissue can also form cysts on the ovaries. Some of these are called 'functional' cysts and may not cause any problems. Another form of cyst, known as 'endometrioma', or 'chocolate' cysts (so called due to their appearance), can cause intense pain and spill their contents inside the pelvic cavity if they rupture, this can then lead to mere adhesion's.

Endometriosis is not an infection.
Endometriosis is not contagious.
Endometriosis is not cancer.