Fibroids are non-cancerous growths that grow in or around your womb (uterus) and may cause heavy or painful periods. They're also called:

  • Fibroids in the womb
  • Fibromyomas
  • Leiomyomas
  • Uterine fibroids
  • Uterine myomas

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2021

What are fibroids?

Fibroids are growths made of fibrous tissue and muscle. They can be as small as a pea or grow as large as a melon. You may have more than one fibroid.

Around one in five women between 30 and 50 years have fibroids. The risk of having them is higher if you:

  • Are of African or Caribbean origin
  • Are overweight — this increases levels of the sex hormone oestrogen, which is linked to the growth of fibroids
  • Have a diet low in fruit and vegetables
  • Have a family history of fibroids
  • Use the contraceptive pill

Your risk of having fibroids decreases if you are a woman who has had a child. The more children you have the lower your risk of fibroids. 

You may not realise you have fibroids, as sometimes there are no symptoms. However, the condition can cause problems, including heavy or painful periods and, occasionally, infertility, so it's important to see a GP if you're concerned.

Fibroids mostly disappear naturally after the menopause.

Types of fibroids

There are three main types of fibroids: 

  • Intramural — these are the most common type and develop in the muscle that forms the wall of the womb 
  • Subserosal — these develop outside the wall of the womb and grow into the pelvis, where they can become very large
  • Submucosal — these develop in the muscle that sits under the inner lining of the womb and grow into the womb cavity

Sometimes subserosal or submucosal fibroids attach to the womb via a stalk of tissue — these are pedunculated fibroids. 

How to tell if you have fibroids

Around one in three women with fibroids have symptoms, including:

Fibroids do not interfere with the menstrual cycle but can make periods heavier. This can cause low iron levels or anaemia

Complications of fibroids

In rare cases, fibroids can make it difficult to become pregnant or cause infertility by preventing a fertilised egg from attaching to the womb lining or by preventing sperm from reaching an egg.

If you are pregnant, fibroids can cause problems with the development of your baby and increase your risk of premature labour. They may also cause problems during labour. If they block your vagina, you may need a caesarean section. In rare cases, fibroids can cause miscarriage. 

Talk to your doctor if you’re concerned about symptoms

You can book an appointment with a Spire private GP today.

Diagnosis and tests for fibroids

Two out of three women with fibroids do not have any symptoms and are sometimes diagnosed by chance during a routine gynaecological examination. 

If you have ongoing fibroid symptoms, tell your GP. They'll perform a pelvic examination and, if necessary, an ultrasound scan that will show any fibroids in your womb.

There are two types of ultrasound scan used to diagnose fibroids, abdominal and transvaginal. All ultrasound scans are painless. They use a probe that produces high-frequency sound waves to create images of the inside of your body. Your doctor can then examine these images for signs of fibroids. 

You may be referred to a gynaecologist (a doctor specialising in the female reproductive system) for further investigations, such as:

  • Hysteroscopy — a thin, tube-like telescope is inserted through your vagina and used to look for fibroids inside your womb; this five minute procedure is usually done under local anaesthetic so you won't feel any pain but you may experience some cramping
  • Laparoscopy — a thin, tube-like telescope is inserted through a small incision in your abdomen and used to look for fibroids in the muscle surrounding your womb or outside your womb; this is done under general anaesthetic

During these procedures, a small tissue sample (biopsy) may be removed to examine under a microscope.

Causes of fibroids

The exact cause isn’t always known. However, oestrogen and progesterone may cause fibroids to grow. These are female sex hormones that cause the lining of your womb to develop again after each menstrual cycle. 

Fibroids commonly develop during your reproductive years when your oestrogen levels are at their highest. They usually shrink after menopause when your oestrogen levels decrease. 

If you're pregnant, the natural increase in the production of oestrogen and progesterone can cause fibroids to grow quickly.

Common treatments for fibroids

Fibroids without symptoms don't need treatment. They'll often shrink and disappear by themselves over time. If you have symptoms, these will usually reduce or stop completely after menopause when your oestrogen levels decrease.

A common symptom of fibroids is heavy or painful periods. Treatments to reduce heavy periods include: 

  • Contraceptive pill 
  • Injected progestogen delivered once every 12 weeks for as long as needed; this is a contraceptive and stops your womb lining from growing so quickly — side effects include:
    • Irregular bleeding
    • No periods
    • Premenstrual symptoms, such as bloating, breast tenderness and fluid retention 
    • Weight gain
  • LNG-IUS (levonorgestrel intrauterine system), a small, plastic T-shaped device placed in your womb that releases the sex hormone levonorgestrel, which stops your womb lining from growing so quickly — side effects include:
    • Acne
    • Breast tenderness
    • Headaches
    • Irregular vaginal bleeding — this may last for six months or longer
    • No periods 
  • NSAIDs (non-steroidal anti-inflammatory drugs) taken three times a day to reduce your body's production of the sex hormone prostaglandin — common side effects include diarrhoea and indigestion
  • Oral progestogen taken once a day from days 5 to 26 of your menstrual cycle to stop your womb lining from growing so quickly — this is not a contraceptive and side effects include acne, breast tenderness and weight gain
  • Tranexamic acid taken three or four times a day during your period for up to four days to stop bleeding from small blood vessels in your womb lining — this is not a contraceptive and side effects include diarrhoea and indigestion

There are also treatments to shrink your fibroids:

  • GnRHas injections to stop the production of oestrogen by your pituitary gland — this can be used to shrink fibroids before surgery to remove them but is also used to reduce heavy periods and discomfort due to pressure on your stomach; side effects include:
    • Hot flushes
    • Increased sweating
    • Muscle stiffness
    • Vaginal dryness
  • Ulipristal acetate tablets for women aged over 18 who have not gone through the menopause, have moderate to severe symptoms and are either waiting for surgery or can’t have surgery to remove their fibroids — side effects include: 
    • Dark urine
    • Itchy skin
    • Liver damage
    • Severe tiredness, nausea and/or vomiting
    • Stomach ache on the upper right side of your body
    • Yellowing of your eyes or skin

If you have severe symptoms and medication is not working, your doctor may advise surgery, such as a:

  • Hysterectomy to remove your womb — this is the most effective way to stop fibroids returning and may be recommended if you have severe bleeding or very large fibroids
  • Hysteroscopic resection of your fibroids — a thin, tube-like telescope and small surgical instruments are used to remove your fibroids
  • Hysteroscopic morcellation of fibroids — a surgical instrument called a morcellator is used to cut out and remove your fibroids
  • Myomectomy to remove fibroids from the wall of your womb — fibroids may return after this procedure but this option is preferable to a hysterectomy for women who still want to have children

Non-surgical procedures to shrink or remove your fibroids include: 

  • Endometrial ablation to remove your womb lining
  • MRI-guided procedures — MRI (magnetic resonance imaging) is used to guide small needles into the centre of your fibroid so that it can be destroyed by passing laser or ultrasound energy through the needle into the fibroid
  • UAE (uterine artery embolisation) — the blood vessels that supply your fibroids are blocked, causing your fibroids to shrink over the next 6–9 months, with symptoms improving in three months; one in three women will need further treatment after this procedure

Frequently asked questions

What does fibroid pain feel like?

Large fibroids can make you feel a pressure pushing down on your pelvis or a fullness. They can also cause pain in your lower back and/or stomach area. You may also experience pain during intercourse if your fibroids are pushing into the wall of your vagina.

How do I know if I have fibroids?

Most women with fibroids do not have any symptoms. However around one in three women with fibroids do have symptoms, including:

If you are concerned that you might have fibroids, see your GP.

What happens if fibroids go untreated? Fibroids without symptoms don't need treatment. They'll often shrink and disappear by themselves over time. However, if you do have symptoms and don’t seek treatment, your fibroids may grow and cause pain or discomfort during sex, stomach and/or lower back pain, anaemia due to heavier periods, constipation and a frequent need to urinate. In rare cases, they can also make it difficult to become pregnant or cause infertility.

Fibroids without symptoms don't need treatment. They'll often shrink and disappear by themselves over time. However, if you do have symptoms and don’t seek treatment, your fibroids may grow and cause pain or discomfort during sex, stomach and/or lower back pain, anaemia due to heavier periods, constipation and a frequent need to urinate. In rare cases, they can also make it difficult to become pregnant or cause infertility.

Are fibroids serious?

For most women, fibroids are not serious and will shrink and disappear over time. However, for one in three women with fibroids, they can cause pain and discomfort that affects their quality of life. In rare cases, fibroids can make it difficult to become pregnant or cause infertility.

Treatments are available to reduce your symptoms and remove your fibroids. If you are concerned that you have fibroids or your fibroids are affecting your quality of life, see your GP.

Can fibroids come out as clots?

No, fibroids do not naturally pass out of your body. However, they can cause heavier periods. This can cause large clots, which will pass out during your period.

Can fibroids come out during a period?

No, fibroids do not naturally pass out of your body. However, they can cause heavier periods. This can cause large clots, which will pass out during your period.

https://www.nhs.uk/conditions/fibroids

https://patient.info/health/periods-and-period-problems/fibroid

https://www.womenshealth.gov/a-z-topics/uterine-fibroid

https://www.healthline.com/health/uterine-fibroids#causes

www.uofmhealth.org/health-library/hw178640