Endometriosis is a common condition where tissue that behaves like the lining of the womb (the endometrium) is found outside the womb.

These pieces of tissue can be found in many different areas of the body, including:

  • the ovaries and fallopian tubes
  • outside the womb
  • the lining of the inside of the abdomen
  • the bowel or bladder

The condition is estimated to affect around two million women in the UK. Most of them are diagnosed between the ages of 25 and 40.

Endometriosis is rare in women who have been through the menopause.

Symptoms of endometriosis

Endometriosis is a long-term (chronic) condition. Symptoms can vary significantly from person to person, and some women have no symptoms at all.

The most common symptoms include:

  • painful periods or heavy periods
  • pain in the lower abdomen (tummy), pelvis or lower back
  • pain during and after sex
  • bleeding between periods
  • difficulty getting pregnant

Most women with endometriosis get pain in the area between their hips and the tops of their legs. Some women experience this pain all the time.

Other symptoms may include:

  • persistent exhaustion and tiredness
  • discomfort when going to the toilet
  • bleeding from your back passage (rectum) or blood in your poo
  • coughing blood – in rare cases when the endometriosis tissue is in the lung

How severe the symptoms are depends on where in your body the abnormal tissue is, rather than the amount of tissue you have. A small amount could be more painful than a large amount.

What causes endometriosis?

The causes of endometriosis aren't fully known, but there are several theories.

The most widely accepted theory is the womb lining doesn't leave the body properly during a period and embeds itself on the organs of the pelvis. This is known as retrograde menstruation.

However, this doesn't explain why the condition can occur in women who have had a hysterectomy.

Read about the possible causes of endometriosis.

Diagnosing endometriosis

See your GP if you have symptoms of endometriosis so they can try to identify a cause. They may refer you to a gynaecologist, a specialist in problems affecting the female reproductive system.

It can be difficult to diagnose endometriosis because the symptoms can vary considerably, and many other conditions can cause similar symptoms. 

Your gynaecologist will ask about your symptoms, your periods and possibly your sexual activity. They may also carry out an internal pelvic exam or recommend an ultrasound scan to look for cysts in your ovaries that may have been caused by endometriosis.


Endometriosis can only be confirmed with a surgical examination called a laparoscopy. This is carried out under general anaesthetic (where you're put to sleep) and you can usually go home the same day.

A thin tube with a light on the end (laparoscope) will be passed into your body through a small cut in your skin at your belly button. It has a tiny camera that transmits images to a video monitor so the specialist can see any endometriosis tissue.

During the procedure, a small sample of tissue (biopsy) can be taken for laboratory testing, or other surgical instruments can be inserted to treat the endometriosis. 

How endometriosis is treated

The symptoms of endometriosis can often be managed with painkillers and hormone medication, which help prevent the condition interfering with your daily life. However, there's no known cure for endometriosis.

Patches of endometriosis tissue can sometimes be surgically removed to improve symptoms and fertility.

Endometriosis can be a difficult condition to deal with, both physically and emotionally. Charities such as Endometriosis SHE Trust UK and Endometriosis UK can offer advice and support to help you cope.

Read more about treating endometriosis.

Endometriosis and pregnancy

One of the main complications of endometriosis is difficulty getting pregnant or not being able to get pregnant at all (infertility).

Although surgery can't guarantee you'll be able to get pregnant, there's good evidence that removing endometriosis tissue with a laser or an electric current during keyhole (laparoscopic) surgery can improve your chances of having a successful pregnancy.

If you have endometriosis and you do become pregnant, the condition is unlikely to put your pregnancy at risk. Pregnancy sometimes reduces the symptoms of endometriosis, although they often return once you've given birth and finished breastfeeding, and the menstrual cycle returns to normal.

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Page last reviewed: 09/11/2015

Next review due: 09/11/2017