Endometriosis is a common condition in which small pieces of the womb lining, known as the endometrium, are found outside the womb in places such as the fallopian tubes, ovaries, bladder, bowel, vagina or rectum.
Endometriosis commonly causes pain in the lower abdomen (tummy), pelvis or lower back. It may also lead to fertility problems (see Symptoms for more information). However, some women have few or no symptoms at all.
The cause of endometriosis is uncertain, but there are several theories (see Causes for more information).
What happens
The endometriosis cells behave in the same way as those that line the womb, so every month they grow during the menstrual cycle and are shed as a bleed.
Normally before a period, the endometrium thickens to receive a fertilised egg, in response to a release of the hormone oestrogen. When pregnancy does not happen, this lining breaks down and leaves the body as menstrual blood (a period).
Endometriosis tissue anywhere in the body will go through the same process of thickening and shedding, but it has no way of leaving the body and is trapped. This leads to pain, swelling and sometimes damage to the fallopian tubes or ovaries, causing fertility problems.
Who is affected?
Endometriosis affects around two million women in the UK, most of whom are diagnosed between the ages of 25 and 40.
Outlook
There is no known cure for endometriosis. It is a chronic (long-term) condition that can cause pain, lack of energy, depression and fertility problems. However, symptoms can be managed and fertility improved through the use of pain medication, hormone treatment or surgery, so that the condition does not interfere with your daily life.
