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Endometriosis is a condition affecting women, in which cells that normally line your womb (uterus) grow outside the lining of your womb. These cells go through the same monthly changes as the womb lining itself, sometimes swelling and bleeding into your body.

About endometriosis

If you have endometriosis, cells like the ones found in your womb lining (endometrium) grow on other organs outside the lining of your womb. Endometriosis is most common on your ovaries, fallopian tubes and the tissues that hold your womb in place. You can also get endometriosis on or around other organs in your pelvis and abdomen (tummy), such as your vagina, bladder or bowel. Rarely, endometriosis can occur in the space around your lungs or in the muscle of your womb. 

Normally, before you have your period, your endometrium will thicken to receive a fertilised egg. When an egg is released and isn’t fertilised (if you don’t get pregnant), the lining of your womb will break down and will leave your body as menstrual blood (a period). If you have endometrial tissue elsewhere in your body, it will go through the same process of thickening and breaking down, but it has no way of leaving your body. This can lead to pain, swelling and scarring, which can damage your fallopian tubes or ovaries and cause fertility problems.

Illustration showing the womb and surrounding structures 

Estimates vary, but around five to 10 in 100 women are affected by endometriosis. It can affect any woman of childbearing age.

Symptoms of endometriosis

The symptoms of endometriosis can vary. You may have no symptoms at all. The most common symptom is chronic pelvic pain that feels like period pain. A chronic illness is one that lasts a long time, sometimes for the rest of the affected person’s life. When describing an illness, the term chronic refers to how long a person has it, not to how serious a condition is.

Other symptoms you may have include:

  • pain during sex
  • changes to your periods, such as spots of blood before your period is due, irregular bleeding or heavy periods
  • painful bowel movements
  • extreme tiredness

If you have any of these symptoms, see your GP.

Endometriosis on your bowel can cause swelling in your lower abdomen or pain when you have a bowel movement. You may also have blood in your faeces during a period. If you have endometriosis on your bladder, it can cause pain when you urinate. Some women find that their symptoms go away without any treatment, but for most women the condition will continue to cause problems.

If you become pregnant and have endometriosis, the pain may get better during your pregnancy and then come back after you give birth.

Symptoms of endometriosis usually get better or disappear after the menopause.

Complications of endometriosis

Complications of endometriosis include those listed below.

  • The bleeding can form bands of scar tissue (adhesions) that can attach to the organs in your pelvis and abdomen.
  • Your fertility may be reduced. This could be due to adhesions forming on or near to your ovaries or fallopian tubes, or because the endometriosis changes how well your womb functions, or there may be no obvious cause.
  • Endometriosis increases your risk of getting ovarian cysts. These can bleed or rupture, causing severe pain.
  • Endometriosis of the intestine can cause your bowel to become blocked or twisted.
  • You may be at an increased risk of certain types of cancer, particularly ovarian cancer.

Causes of endometriosis

The exact cause of endometriosis is unknown; however, there are several theories about why some women may get it.

One theory is that your immune system isn’t functioning properly. Usually your immune system would destroy any endometrial tissue that's growing outside the lining of your womb, but with endometriosis, this doesn’t appear to happen.

It appears that endometriosis may be inherited, so you’re more likely to get it if your mother or sister has it too.

A process known as retrograde menstruation may be partly to blame. In retrograde menstruation, cells from your womb flow backwards into your body through your fallopian tubes. Once in your body, they continue to react to oestrogen, causing the pain and inflammation associated with endometriosis. However, almost all women have some retrograde menstruation, so it’s not known why it seems to lead to endometriosis in only some of these women. More research is needed to pinpoint what causes endometriosis.

There are certain factors that may make you more likely to get endometriosis. For example, you're more likely to get it if you:

  • started your periods early
  • have frequent, heavy or painful periods
  • haven’t had any children

It’s likely that a combination of factors leads to endometriosis developing.

Diagnosis of endometriosis

Your GP will ask you about your symptoms. You may need to have a vaginal examination. Your GP may refer you to a gynaecologist (a doctor who specialises in women's reproductive health).

The only way to be sure that you have endometriosis is to have a gynaecological laparoscopy. This is a procedure used to examine your fallopian tubes, ovaries and womb. Once you have a diagnosis, your doctor will be able to recommend the most appropriate treatment for you. Many women find it takes a number of years to get a diagnosis of endometriosis because the symptoms are similar to lots of different conditions.

Treatment of endometriosis

There is currently no cure for endometriosis, but treatments are available to manage your symptoms. The type of treatment you have will depend on your age, the severity of your symptoms and whether or not you want to have children.


If you need pain relief, you can take over-the-counter painkillers, such as ibuprofen. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.

The combined oral contraceptive is one of the most common treatments for endometriosis, but it isn't licensed for this condition and is prescribed ‘off-label’. This means the medicine is being used to treat a condition that it hasn’t been licensed for and isn't listed in the patient information leaflet that comes with the medicine. Your doctor can legally prescribe outside the licence if he or she feels the medicine will be effective for you.

There are other hormonal medicines available that your doctor can prescribe to reduce the amount of oestrogen in your body. These can help to reduce the size of the endometriosis and ease your symptoms. Some examples are:

  • gonadotrophin-releasing hormone (GnRH) analogues (eg buserelin)
  • progestogens (eg norethisterone)

These hormonal treatments all have different side-effects. Your doctor may suggest trying several different hormonal medicines one at a time to find one that works best for you. There may be time limits for how long you can be prescribed a hormonal treatment, for example, GnRH analogues aren’t usually prescribed for longer than six months. Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Some hormonal medicines can harm a developing baby. So, it’s important to use an effective method of contraception (such as condoms or an intrauterine device) to prevent getting pregnant while taking these medicines. Ask your doctor for advice.


Surgery can remove areas of endometriosis. This can help to improve your fertility if the endometriosis is interfering with your womb and ovaries.

There are different types of surgery, depending on where the endometriosis is and how extensive it is. Your gynaecologist can cut away the endometriosis, or he or she can destroy it with heat from an electric current or a laser (endometrial ablation).

Surgery can usually be done by keyhole surgery (laparoscopy – the same procedure you will have had during your diagnosis). Your gynaecologist will make small cuts in your abdomen and then use a laparoscope (a narrow, flexible, tube-like telescopic camera) to view the inside of your pelvis. He or she will use special keyhole instruments to remove the endometriosis.

If you have severe and extensive endometriosis, you may need to have open surgery (a laparotomy), in which your gynaecologist will make a larger cut in your abdomen. However, you will be offered keyhole surgery whenever possible.

If you have very severe symptoms, your doctor may advise you to have an operation to remove your womb (and sometimes your ovaries). This is called a hysterectomy.

In many women, endometriosis can come back after surgery, even after a hysterectomy. Your gynaecologist will give you more information about which option might be best for you. Please see our frequently asked questions for more information about endometriosis and having a hysterectomy.


Produced by Louise Abbott, Bupa Health Information Team, February 2013.

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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