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

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

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


Symptoms of endometriosis can vary and some women experience symptoms while others may not. The most common symptom is chronic pelvic pain which feels similar to menstrual cramps. The pain often correlates to the menstrual cycle, however a woman with endometriosis may also experience pain at other times during her monthly cycle.

Endometriosis is described as a chronic illness as it lasts a long time, sometimes for the rest of the affected persons life. When describing an illness, the term chronic refers to how long a person has it, not to how serious a condition is.

The symptoms of endometriosis can vary in intensity. For many women, but not every woman, the pain of endometriosis can unfortunately be so severe and debilitating that it impacts on her life so that she may not be able to carry out normal day to day activities.

The most common symptoms of endometriosis are
:: pain in the lower abdomen, pelvis or lower back
:: changes to your periods such as spotting before your period is due
:: pain before, during or after your period
:: painful, heavy or irregular periods
:: painful menstrual cramps
:: pain during or after sex
:: abdominal bloating
:: painful or problematic bowel movements including diarrhoea or constipation
:: pain on passing urine
:: extreme fatigue
:: nausea
Image courtesy of http://www.endometriosis-uk.org/information/symptoms.html
Most women with endometriosis may also experience pain in the area between their hips and the tops of their legs.

Another symptom of endometriosis can be infertility. It is estimated that 30-40% of women with endometriosis are sub-fertile (the condition of being less than normally fertile though still capable of effecting fertilisation). Infertility is not always caused by endometriosis - it can be due to many other factors.

Endometriosis is often classified as mild, moderate or severe or as stage I-IV.

:: Mild or stage I endometriosis small patches, surface lesions or inflammation on or around organs in the pelvic cavity.
:: Moderate or stage II-III endometriosis sometimes more widespread and starting to infiltrate pelvic organs, peritoneum (pelvic side walls) or other structures. Sometimes there is also scarring and adhesions.
:: Severe or stage IV endometriosis infiltrative and affecting many pelvic organs and ovaries, often with distortion of the anatomy and adhesions.

These stages provide a useful guideline however they also have limitations. For instance, the amount of endometriosis does not always correspond to the amount of pain and discomfort. A small amount of endometriosis can be more painful than severe endometriosis. It depends, largely, on where the endometriosis is actually growing inside the body.

All of the symptoms above may have other causes. It is important to seek medical advice to clarify the cause of any symptoms you may experience. If your symptoms change after diagnosis, it is important to discuss these changes with a medical practitioner. It is easy to attribute all your problems to endometriosis, but it may not always be the cause of your symptoms. The symptoms of endometriosis can also indicate many other conditions and because endometriosis manifests itself in a variety of ways, diagnosis can be difficult.


Long term (chronic) pelvic pain is the most common complaint for women with endometriosis, and it can significantly impair the quality of life, including work and social activities.

Women commonly describe active endometriosis pain as burning, dull, heavy and miserable.

The main complication of endometriosis is difficulty in getting pregnant (sub-fertility) or not being able to get pregnant at all (infertility).

Endometriosis does not equal infertility! Little research has been carried out when it comes to endometriosis and fertility, but, it is important to remember that having endometriosis does not automatically mean that you will never have children. Rather, it means that you may have more problems in getting pregnant.

Studies indicate that women with minimal-mild endometriosis take longer to conceive (become pregnant) and are less likely to conceive than women in general. It also appears that the more severe the woman's endometriosis, the more likely it is that she will have difficulty becoming pregnant. Thus, women with moderate-severe endometriosis tend to have more difficulty conceiving than women with minimal-mild endometriosis.

Many women with endometriosis have children without difficulty, and many others become pregnant eventually - though it may take time. Surgery can improve fertility by removing endometriosis tissue, but there is no guarantee that this will allow you to get pregnant. You may also require the help of assisted reproductive technologies.

The longer someone has endometriosis, the greater the chance that their fertility will be affected. However, it is estimated that up to 70% of women with mild-moderate endometriosis will still be able to get pregnant without treatment. Pregnancy is also known to reduce the symptoms of endometriosis, although the symptoms often return once the menstrual cycle returns to normal.

Infertility can be related to scar formation and anatomical distortions due to the endometriosis; however, endometriosis may also interfere in more subtle ways: cytokines and other chemical agents may be released that interfere with reproduction.

Effects on other parts of the pelvic region
Ovarian cysts (fluid-filled cysts in the ovaries) can form when the endometriosis tissue is in or near the ovaries. In some cases, ovarian cysts (endometriomas) can become very large and painful. They can bleed or rupture, causing severe pain.

Adhesion's are bands of fibrous scar tissue, which forms inside the body. They can be found anywhere in the body between almost all organs and tissue. For women with endometriosis, they can bind an ovary to the side of the pelvic wall, or they may extend between the bladder and the uterus etc.

Whilst adhesion's are more often than not spoken of as a post-operative complication, this does not necessarily hold entirely true for women with endometriosis, even though they, of course, are a group of people who often have had numerous surgeries and thereby, by that factor alone, increase their risk of developing further adhesion's.

Endometriosis, however, can cause local inflammation, which is a key factor in adhesion formation. Adhesion's may therefore form as a result of endometrial implants bleeding on to the area around them, causing inflammation, which again leads to the formation of scar tissue as part of the healing process.

Adhesion's vary in appearances from thin and transparent to thick, dense and opaque. In some cases, adhesion's have been found to such an extent throughout the pelvis to create what is known as a 'frozen' or 'fixed' pelvis.

Just like endometriosis itself, adhesion's can cause pain and subsequently affect a woman's quality of life to the extent that her day-to-day activities are impaired. Women with endometriosis describe the pain associated with adhesion's as stabbing, sharp, pulling, intense and nauseating.

Yet, whilst the problem of adhesion's in endometriosis is widely recognised, there is at the moment no way of preventing them, when caused by the disease alone, nor a fool proof prophylactic which can be applied during surgery, though many companies are at present working on finding a product which prevents adhesion's.

Other complications can include
:: bowel obstruction implants can sometimes form in the intestine and cause painful bowel movements, constipation or diarrhoea
:: ureteral obstruction implants can occur in the bladder (although less commonly) and cause pain and even bleeding during urination
:: peritonitis from bowel perforation can occur
:: an increased risk of certain types of cancer, particularly ovarian cancer
:: an increased risk of miscarriage or giving birth prematurely there is no evidence that endometriosis causes women to have repeated miscarriages, also, there is no evidence that treating endometriosis results in women having fewer miscarriages.


The actual cause of endometriosis is unknown. There are many theories, but none fully explain why the condition occurs.

Most scientists working in the field of endometriosis do agree, however, that it is exacerbated by oestrogen. Subsequently most of the treatments for endometriosis attempt to temper oestrogen production in a woman's body in order to relieve her of symptoms.

Several theories have become more accepted, and it is possible that a combination of these factors could be causing endometriosis to develop in some women.

Retrograde menstruation
This theory was promoted by Dr John Sampson in the 1920's. When you have a period, some of the endometrium (lining of the womb) flows backwards, out through the fallopian tubes and in to the abdomen. This tissue then implants itself on organs in the pelvis and grows. It has been suggested that most women experience some form of retrograde menstruation, but their bodies are able to clear this tissue and it does not deposit on the organs. This theory does not explain why endometriosis has developed in some women after hysterectomy, or why, in rare cases, endometriosis has been discovered in some men when they have been exposed to oestrogen through drug treatments.

Genetic predisposition
The theory is that endometriosis is passed down to new generations through the genes of family members. Some families may be more susceptible to endometriosis.

Lymphatic or circulatory spread
The theory is that endometriosis tissue particles somehow travel round the body through the lymphatic system or in the bloodstream. This could explain why it has been found in areas such as the eyes and brain.

Immune dysfunction
The theory is that for some women, their immune system is not able to fight off endometriosis. Many women with endometriosis appear to have reduced immunity to other conditions. It is not known whether this contributes to endometriosis or whether it is a result if endometriosis.

Environmental causes
The theory is that certain toxins in our environment, such as dioxin, can affect the body, the immune system and reproductive system and cause endometriosis. Research studies have shown that when animals were exposed to high levels of dioxin they developed endometriosis. This theory has not yet been proven for humans.

Metaplasia is the process where one type of cell changes or morphs in to a different kind of cell. Metaplasia usually occurs in response to inflammation and enables cells to change to their surrounding circumstances to better adapt to their environment.

In the case of endometriosis, metaplasia would explain how the endometriosis cells appear spontaneously inside the body - and how they appear in areas such as the lungs and skin. It would also explain the appearance of endometriosis cells in women with no womb - or in men who have taken hormone treatments.

During development in the womb. metaplasia allows for the development of the human body as a natural process.To explain endometriosis, some researchers believe this change from one type of cell in to an endometriosis cell happens as an embryo (developing baby in the womb), when the baby's womb (uterus) is first forming.

Others believe that some adult cells retain the ability they had as an embryo, to transform in to endometriosis cells.