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Endometriosis is a condition where tissue similar to the lining inside your womb (uterus) starts to grow in other parts of your body, such as your ovaries, bowel or bladder, and the lining inside your tummy (abdomen). The lining tissue is called endometrium.

If the tissue grows on your ovaries, it can sometimes form ovarian cysts (fluid-filled sacs).

Endometriosis is very common and can happen at any age. It affects at least one in 10 women (usually in their reproductive years).

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

Causes of endometriosis

We do not know the exact cause of endometriosis, but it's believed that it may be due to a combination of factors. Theories about what causes endometriosis include:

Symptoms of endometriosis

About a third of women with endometriosis have no symptoms. If you do have symptoms, they usually happen around the time you get your period. The most common symptom of endometriosis is pelvic pain. Other symptoms include:

Endometriosis can cause problems with getting pregnant, but this doesn't happen to everyone. It's important to remember that if you have endometriosis and do not want to get pregnant, you still need to use contraception.

Symptoms of endometriosis can have a big impact on your life, and can even lead to feelings of depression. See your GP if you have any concerns about your mood.

Diagnosing endometriosis

It can often be difficult to diagnose endometriosis. Other conditions such as irritable bowel syndrome, adenomyosis and diverticulitis can cause similar symptoms.

Your doctor will ask you about your pelvic pain including the type, frequency, and how severe your pain is. They will also ask about your periods and if you have been trying or wish to become pregnant. It can be helpful to complete a menstrual diary, which is a record of your periods. The diary can help your GP understand when you have period pain. You can also download a period tracker app, called Clue, for iPhones and Android phones, or Period Tracker for Android phones.

Your doctor will examine your tummy, and do an internal (vaginal) examination. They may do blood tests and swabs to check for infections, such as sexually transmitted infections. Endometriosis tissue doesn't usually show on an ultrasound but you may have one to check for other problems such as a cyst on your ovary.

The only way to definitely diagnose endometriosis is to have a laparoscopy (keyhole surgery), which allows your doctor to see inside your pelvis and examine the uterus, ovaries and tubes.

  HealthInfo recommends the following pages

On the next page: Treating endometriosis

Written by GP liaison, Christchurch Women's Hospital. Adapted by HealthInfo clinical advisers. Last reviewed September 2021.


See also:

Pelvic pain in women


Preparing for your doctor's visit

Understanding your vaginal swab results

Page reference: 32552

Review key: HIEND-30280