Your health expert: Dr Madhavi Vellayan, Consultant Gynaecologist
Content editor review by Rachael Mayfield-Blake, January 2023
Next review due January 2026

Endometriosis is when cells similar to those normally found in the lining of your womb (uterus) also appear in other parts of your body, most commonly in your pelvis. When you have your period, these cells can build up and break away in the same way as your womb lining. This causes painful inflammation in surrounding tissues.

An image showing the location of the womb and surrounding structures

About endometriosis

About one in every 10 people assigned female at birth and of child-bearing age has endometriosis. But it could affect as many as half of people who have infertility. Endometriosis usually becomes inactive after the menopause but not always.

During your period (menstrual cycle), your womb lining thickens to receive a fertilised egg. If you don’t get pregnant, the lining of your womb breaks down and leaves your body as menstrual blood (a period) each month. This process is controlled by your body’s hormones.

In endometriosis, cells like those that line your womb (endometrial tissue) are also elsewhere in your body. This tissue thickens, breaks down and bleeds with your menstrual cycle. Your body does get rid of the broken-down tissue and blood but very slowly. While it’s there, it causes scarring, irritation and as a result, pain.

Endometriosis usually affects tissues inside your pelvis. It’s most common in and around your ovaries, the surrounding ligaments and between your womb and the end part of your bowel (rectum). If you have endometriosis on your fallopian tubes or ovaries, it can lead to fertility problems.

Endometriosis can affect other parts of your body, such as your lungs, but this is rare.

Endometriosis isn’t a type of cancer, and you can’t catch it or give it to anyone else.

Causes of endometriosis

Doctors don’t really know what causes endometriosis yet. There are lots of different ideas about how it develops but none of these fully explain why endometriosis happens. It’s probably caused by a combination of things. For example, your immune system or hormones might play a role. Endometriosis may also run in families, as you’re more likely to get it if your mother or sister has it.

Some things may increase your risk of getting endometriosis. These include if you:

  • started your periods early
  • haven’t given birth to any children
  • have a low body mass index (BMI)
  • have an autoimmune disease, which means it’s caused by your own immune system attacking healthy body tissues
  • smoke

Symptoms of endometriosis

One of the most common symptoms of endometriosis is pain in your pelvis, which is usually worse just before and during your period. The endometriosis pain may get worse over time and you may find that it doesn’t get better when you take over-the-counter painkillers, such as ibuprofen.

Other endometriosis symptoms include:

  • pain during sex
  • heavy periods
  • extreme tiredness (fatigue)
  • difficulty getting pregnant (conceiving)

You may become depressed or anxious because of the long-term pain.

There are some fewer common symptoms of endometriosis.

  • Endometriosis on your bowel can cause pain when you poo (have a bowel movement). You may have blood in your poo during your period too.
  • If you have endometriosis on your bladder, it can be painful when you pee (pass urine). You may also see blood in your pee.

These symptoms can also be caused by conditions other than endometriosis. So if you have any of them, see a GP.

Symptoms of endometriosis often ease during pregnancy, and they may disappear without any treatment.

Some women have no symptoms of endometriosis. You may only find out that you’ve got it after having tests for something else, such as infertility.

infographic showing first symptom of endometriosis: Painful or heavy periods
Infographic showing a symptom of endometriosis: fatigue
Infographic showing the second symptom of endometriosis: Pain in lower abdominal area
Infographic showing the third symptom of endometriosis: Painful sex
Graphic showing the fourth common symptom of endometriosis: Problems with fertility
Infographic showing the fifth symptom of endometriosis: Feeling depressed

Diagnosis of endometriosis

A GP will ask about your symptoms to help make an endometriosis diagnosis. Don’t be embarrassed to tell them about the problems you’re having – including pain during sex, or seeing blood when you go to the toilet. It’s important that they know everything.

A GP may offer you the following tests, or refer you to a gynaecologist (a doctor who specialises in women’s reproductive health) for them.

A vaginal or rectal examination

  • In a vaginal examination, a GP will put some gloves on and add some lubricant, then insert their fingers into your vagina. They’ll use their other hand to press lightly on your tummy (abdomen). The GP will gently feel for any abnormalities in and around your womb.
  • In a rectal examination, a GP will again put on some gloves and lubrication, then insert their finger into your back passage (anus).

These examinations may feel uncomfortable but shouldn’t be painful. Let the GP know if anything hurts. You can ask to have someone stay with you while a GP does these tests, if you prefer.


You may have an ultrasound scan, using a probe that’s put into your vagina. This can help to pick up endometriosis or other causes of your symptoms. But there’s a chance that it won’t pick up endometriosis, even if you have it.

You might also be offered a magnetic resonance imaging (MRI) scan. This can help to diagnose endometriosis that’s deep inside your pelvis, or that affects your bladder or bowel.


It can take time diagnosing endometriosis because the symptoms are similar to other health conditions. The only way doctors can be sure is to check with a procedure called a laparoscopy. You have this under general anaesthetic so you’ll be asleep. Your gynaecologist will look inside your tummy (abdomen) with a laparoscope. This is a narrow tube with an eyepiece that they will put into your tummy through a small cut. They may take a small sample of tissue (biopsy) to send to the lab for examination under a microscope.

If you have a laparoscopy to diagnose endometriosis, your gynaecologist may destroy or remove the endometriosis at the same time. Or they may recommend you have surgery to remove it later. See our section on Treatment below.

Sometimes, rather than having this procedure right away, your doctor may suggest you try other treatments first, such as hormonal medicines, to see if they help.

Treatment of endometriosis

If you need treatment for your endometriosis symptoms, the type of treatment you will have will depend on how bad your symptoms are, and whether or not you want to have children in the future.

Your doctor will discuss the various options with you, and help you decide which treatment is best.

Pain medicines

Your doctor will probably suggest that you try a non-steroidal anti-inflammatory medicine (NSAID), such as ibuprofen to ease pain and discomfort. Paracetamol is an alternative that you can take alone or with an NSAID. You can buy these pain medicines over the counter from a pharmacy. Always read the patient information leaflet that comes with your medicine. If you have any questions, ask a pharmacist for advice.

Hormone treatments

Hormone treatments can help to reduce areas of endometriosis tissue and so lessen your pain. They aren’t suitable to treat endometriosis if you’re trying to get pregnant as they’re contraceptives. But they won’t have any effect on having children in the future.

Your doctor may offer you the combined oral contraceptive pill. This may be for around six months at first, but if it’s helpful, you’ll usually be able to carry on taking it.

If that doesn’t help, or doesn’t suit you, there are several other types of hormonal treatment that your doctor may offer. These include:

  • progestogens, which you can take as tablets, have as an injection every three months or in an intrauterine system (coil)
  • gonadotrophin-releasing hormone (GnRH) agonists, which you have as injections, an implant, or a nasal spray

Each of these treatments has different side-effects. Your doctor can explain these and discuss which treatment will suit you best.


It’s possible to have areas of endometriosis removed with surgery. If endometriosis is affecting your fertility, this can help to improve your chance of getting pregnant and can also reduce pain. You have surgery for endometriosis under a general anaesthetic so you’ll be asleep. Endometriosis can come back after surgery, so you may need to have surgery again in the future.

Laparoscopy (keyhole surgery)

You may have a laparoscopy – a type of keyhole surgery to treat endometriosis. Your gynaecologist will look inside your tummy (abdomen) by making a small cut and putting in a narrow tube with an eyepiece (laparoscope). Through the laparoscope, they can see and remove or destroy patches of endometriosis.

Laparotomy (open surgery)

If you have severe endometriosis, keyhole surgery may not be suitable. You may need an operation called a laparotomy where a surgeon will make a larger cut in your tummy (abdomen), usually along your bikini line. Your gynaecologist will explain the procedure and why it may be best for you.


If you don’t want to have children in the future, your gynaecologist may suggest a hysterectomy. This is a larger operation to remove your womb, and often, your ovaries. This operation can also be done using keyhole surgery.

If you have your ovaries removed, you’re likely to have menopausal symptoms afterwards, such as hot flushes. Your specialist may suggest taking hormone replacement therapy (HRT). Talk to your gynaecologist about the pros and cons of this type of surgery.

Complications of endometriosis

Complications of endometriosis include the following.

  • Scar tissue can attach to organs in your pelvis and tummy (abdomen). These scars are known as adhesions and can cause pain.
  • You may have difficulty getting pregnant (reduced fertility). This affects around a third of all women with endometriosis.
  • Endometriosis can cause ovarian cysts (called endometriomas or chocolate cysts). These can rupture and cause pain and affect your fertility.

Endometriosis isn’t a cancer and doesn’t cause cancer. Overall, the risk of all types of cancer is no different for people without endometriosis. Statistically, there’s a slight increase in risk of ovarian cancer, breast cancer and thyroid cancer but the risk is very small.

Speak to a GP or doctor if you have any questions about the complications of endometriosis.

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The best way to confirm a diagnosis of endometriosis is with a laparoscopy. In a laparoscopy, a doctor will put a laparoscope (a narrow tube with an eyepiece) into your tummy through a small cut. This will allow them to look inside and to take a small sample of tissue (biopsy). You have a general anaesthetic, so you’ll be asleep.

See our section: Diagnosis of endometriosis above for more information.

Hormonal treatment for endometriosis can help to ease your pain, but doctors don’t think it increases your chance of getting pregnant. Having laparoscopic surgery to remove or destroy patches of endometriosis may potentially improve your fertility. Fertility treatments may be an option to help you get pregnant if you have endometriosis. Ask your gynaecologist for more information.

The severity of endometriosis can vary – while some people don’t have any symptoms, for others, they can be severe. Endometriosis can also lead to complications, such as difficulty getting pregnant (infertility) and ovarian cysts, which may rupture. This can be very painful but is rare.

See our section: Complications of endometriosis above for more information.

Nothing will necessarily happen if endometriosis is left untreated. There isn’t any evidence that endometriosis will progress and get worse if you don’t get treatment. So, if you don’t have symptoms, your doctor won’t usually recommend treatment. But if you do develop symptoms, it will usually become necessary.

See our section: Treatment of endometriosis above for more information.

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Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, January 2023
Expert reviewer, Dr Madhavi Vellayan, Consultant Gynaecologist
Next review due January 2026

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