Endometriosis (pronounced end-oh-mee-tree-oh-sis) is a painful, chronic and sometimes debilitating condition.

It occurs when cells similar to those found in the lining of the womb (endometrium) are found growing elsewhere in the body. 

Endometriosis is very common. The known incidence is 1 in 10, however, the prevalence is thought to be much higher as there are so many individuals who have the disease but are not diagnosed. It is thought that around 176 million people suffer from endometriosis worldwide.

Endometriosis is not an infection.

Endometriosis is not contagious.

Endometriosis is not cancer.

Where is endometriosis found?

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. This condition is called adenomyosis.

How does endometriosis occur?

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 the 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 organs to become matted together in a web of scar tissue (called adhesions). These can cause chronic pain and may interfere with the normal function of the organ.

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, if ruptured, can spill their contents, which can then lead to more adhesions.