What is Endometriosis?

Endometriosis is a common condition where tissue from the lining of the womb, grows in other areas of the body, such as ovaries, vagina, fallopian tubes, bladder, bowel, or rectum. It mainly affects women during their reproductive years. It can affect women from every social group and ethnicity and affects about 2 million women in the UK.

Endometriosis is not an infection

Endometriosis is not contagious

Endometriosis is not cancer

What are the symptoms of endometriosis?

The symptoms of endometriosis vary and some women may have no symptoms at all.

Most common symptoms include:

  • painful or heavy periods
  • pain during sex
  • long term pain in the lower back, pelvis or abdomen
  • bleeding between periods
  • difficulty in getting pregnant or infertility
  • long term fatigue

The experience of pain varies between women. Most women with endometriosis get pain in the area between their hips and the tops of their legs. Some women have this all the time, while others only have pain during their periods, when they have sex or when they open their bowels.

How severe the symptoms are depends largely on where in your body the endometriosis is. A small amount of tissue can be as painful as a large amount.

Some women with endometriosis become pregnant easily while others have difficulty getting pregnant. The pain may get better during pregnancy and then recur after the birth of the baby. Some women find that their pain resolves without any treatment.

Why does endometriosis occur?

It is not yet known why endometriosis occurs. A number of theories have been suggested but none has been proved.

Retrograde menstruation

The most commonly accepted theory is that, during a period, light ‘backward’ bleeding carries tissue from the womb to the pelvic area via the fallopian tubes. This is called ‘retrograde menstruation’.


Endometriosis is sometimes believed to be hereditary, being passed down through the genes of family members. It can affect women of every ethnicity, but is less common in women of African-Caribbean origin and more common in Asian women than in white women. This suggests that genes may play a part.

Bloodstream or lymphatic system spread

Although it is not known how, endometriosis cells are believed to get into the bloodstream or lymphatic system (a network of tubes, glands and organs that is part of the body's defence against infection). This theory could explain how, in very rare cases, the cells are found in remote places such as the eyes or brain.

Problems with the immune system

It is believed that some women's immune systems are not able to fight off endometriosis effectively. Many women with endometriosis are found to have lower immunity to other conditions. However, this may be a result of the endometriosis rather than the cause of the condition.

Environmental causes

It is thought that endometriosis may be caused by certain toxins in the environment, such as dioxins, that affect the body, the immune system and the reproductive system.

However, while research suggests there is a link between endometriosis and high levels of dioxin exposure in animals, it is not currently known if this is also the case in humans.


Metaplasia is the process of one type of cell changing into another to adapt to its environment. It is this development that allows the human body to grow in the womb before birth.

It has been suggested that some adult cells may retain this ability to change, and that the shedding of menstrual blood or blood products into the pelvis during menstruation may stimulate them to transform into endometrial cells.

How is endometriosis diagnosed?

The tests that are offered are

Ultrasound scan- this can identify whether there is an endometriosis cyst in the ovaries. A normal scan does not rule out endometriosis.

Laparoscopy- this is considered to be ‘the gold standard test’ for the diagnosis of endometriosis.

A laparoscopy is a small operation, which is carried out under general anaesthesia. A small cut is made in your abdomen near your tummy button (navel), and then a telescope (known as a laparoscope), which is about the width of a pen, is inserted. This allows the gynaecologist to see the pelvic organs clearly, look for any endometriosis and can also perform a biopsy for laboratory testing or insert other surgical instruments to treat the endometriosis. You can usually go home the same day after you have had a laparoscopy.

How is endometriosis treated?

There are different treatment options and this will be discussed with you. Several factors will influence the recommended treatment options, such as

  • Your age
  • Your main symptom (pain, fertility problems)
  • If you are planning a pregnancy
  • If you have had any treatments previously
  • If you are anxious about surgery

Although there is no cure for endometriosis, the aim of treatment is to ease the symptoms so that the condition does not interfere with your daily life. Treatment can help to relieve pain, improve fertility, slow the growth of endometriosis, and prevent the disease from coming back.

Treatments for endometriosis:

Pain relief- Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen act against the inflammation and help to ease pain and discomfort

Hormone treatments- There is a range of hormone treatments to stop or reduce ovulation (the release of an egg) to allow the endometriosis to shrink or disappear.

The hormonal methods below are contraceptives and will prevent you from becoming pregnant:

  • The combined oral contraceptive (COC) pill or patch These contain the hormones estrogen and progestogen and work by preventing ovulation and can make your periods lighter, shorter and less painful.
  • The intrauterine system (IUS): this is a small T-shaped device which releases the hormone progestogen. This helps to reduce the pain and makes periods lighter. Some women get no periods at all.

The hormonal methods below are non-contraceptive, so contraception will be needed if you do not want to become pregnant:

  • Use of hormonal progestogens or testosterone derivatives
  • GnRH agonists – these drugs prevent estrogen being produced by the ovaries and cause a temporary and reversible menopause.

Surgery can remove or destroy the areas of endometriotic tissue. The type of surgery used will depend on where the tissue is and how extensive it is. 

What are the surgical options for treatment of endometriosis?

Surgery including hysterectomy does not always successfully remove the endometriosis. There are different types of surgery, depending on where the endometriosis is and how extensive it is. How successful the surgery is can vary and you may need further surgery.

  • Laparoscopic surgery - here the patches of endometriosis are removed by destroying them or cutting them out.
  • Laparotomy If the endometriosis is severe and extensive, you may be offered a laparotomy. This is major surgery which involves a cut in the abdomen, usually in the bikini line.
  • Hysterectomy Some women have surgery to remove their ovaries or womb (a hysterectomy). Having this surgery means that you will no longer be able to have children after the operation.

In many women endometriosis can come back after surgery. You may be advised to take hormonal drugs after surgery to help delay the return of symptoms.