Fibroids are non-cancerous tumours that grow in or around the womb (uterus). The growths are made up of muscle and fibrous tissue and can vary in size. Fibroids are sometimes known as uterine myomas or fibromyomas.

Many women are unaware that they have fibroids as they do not have any symptoms. This often means that fibroids are diagnosed by chance during a routine gynaecological examination, test or scan. If they are suspected, your GP will recommend more tests, such as an ultrasound scan, to confirm fibroids.

What causes fibroids?

The exact cause of fibroids is unknown. However, fibroids are linked to the female hormone, oestrogen. Oestrogen is the female reproductive hormone produced by the ovaries (the female reproductive organs). Fibroids usually develop during a woman’s reproductive years (from approximately 16 to 50 years of age).

Fibroids tend to increase in size when oestrogen levels are at their highest, such as during pregnancy. They are also known to shrink when oestrogen levels are low, such as after the menopause (when a woman’s monthly periods stop at around 50 years of age).

How are fibroids treated?

In many cases, fibroids do not cause symptoms and treatment is not required. Over time, fibroids will often shrink and disappear without any treatment.

However, around 1 in 3 women experience symptoms from fibroids, such as pain or heavy bleeding. In such cases, medication may be prescribed. If this doesn’t work, other techniques, including surgery, may be recommended. Read more about treating fibroids.

In very rare cases, there may be complications due to fibroids, which can make it more difficult to become pregnant or affect a baby during pregnancy.

Types of fibroids

Fibroids can grow anywhere in the womb. The five main types of fibroids are described below.

• Intramural fibroids develop in the muscle wall of the womb and they are the most common type of fibroids found in women.
• Subserosal fibroids grow outside the wall of the womb into the pelvis and can become very large.
• Submucosal fibroids develop in the muscle beneath the inner lining of the womb wall and they grow into the middle of the womb.
• Pedunculated fibroids grow from the outside wall of the womb and are attached to the womb wall by a narrow stalk.
• Cervical fibroids develop in the wall of the cervix (the neck of the womb).

Who is affected?

Fibroids are common, with around 40% of women developing them at some stage in their life. They most often occur in women who are from 30 to 50 years old.

Fibroids are thought to develop more frequently (in around 55%) of women who are of African Caribbean origin. It is also thought that they occur more often in heavier women as a result of higher oestrogen levels.

Many women are unaware they have fibroids because they do not have any symptoms. Around one woman in three with fibroids experiences some symptoms.

If your fibroids do cause symptoms, you may experience one or more of the problems outlined below. In very rare cases further complications caused by fibroids can affect pregnancy or cause infertility.

Heavy or painful periods

Fibroids do not disrupt the normal menstrual cycle (periods), but they can cause heavy or painful bleeding.

If you have heavy periods (menorrhagia), it does not necessarily mean that there is anything seriously wrong. However, it can have a significant impact on your everyday life and lead to anxiety and depression.

In some cases, heavy periods can cause iron-deficiency anaemia, resulting in symptoms such as tiredness, lethargy and shortness of breath (dyspnoea).

Abdominal pain

If you have fibroids, particularly if you have large ones, you may experience discomfort or bloating (swelling) in your stomach. You may also experience pain in your lower back and legs.

Frequent urination and constipation

If your fibroids press on your bladder, you may need to urinate frequently. Fibroids can also press on your rectum (large intestine), which can cause constipation.

Pain or discomfort during sex

If you have fibroids growing near to your vagina or cervix (neck of the womb) you may experience pain or discomfort during sexual intercourse (dyspareunia).

As fibroids often do not cause symptoms, they are usually discovered during a routine gynaecological (vaginal) examination or diagnostic test or scan.

If your GP suspects that you have fibroids, they may recommend that you have some tests to confirm a diagnosis, or to rule out other possible causes of your symptoms. These tests are listed below.

Ultrasound scan

An ultrasound scan of the womb is often used to confirm a diagnosis of fibroids. It can also be used to rule out any other possible causes of your symptoms.

Depending on the results of your ultrasound scan, your GP may refer you to a gynaecologist (a specialist in the female reproductive system). The gynaecologist will be able to investigate the problem further using a number of specialised techniques, such as those outlined below.

Transvaginal ultrasound

A transvaginal ultrasound scan is sometimes used to diagnose fibroids. It is a painless procedure that involves inserting a small probe into your vagina. The probe uses sound waves to create an image of your womb on a TV monitor.

Hysteroscope

It may be possible to see fibroids that are near your inner lining (intramural fibroids) and those within the cavity of your womb (submucosal fibroids) using a hysteroscope. A hysteroscope is a small telescope used to examine the inside of your womb.

Laparoscopy

A laparoscope is a small tube that contains a light source and a camera. The camera relays images of the inside of the abdomen or pelvis to a television monitor. The laparoscope can be flexible or rigid, depending on the procedure, but when diagnosing fibroids a rigid laparoscope is most often used.

The surgeon makes a minor incision in the skin, passes the laparoscope through the incision and studies the organs and tissues inside the abdomen or pelvis.

A laparoscopy can also be used to examine the size and shape of the outside of your womb.

Biopsy

A laparoscopy may be used to take a biopsy (a tissue sample) of the inside lining or the outer layer of your womb. The sample can then be sent to a laboratory for closer examination under a microscope.

Treatment may not be necessary in cases where there are no symptoms of fibroids, or where symptoms are minor.

For example, if you have heavy periods already, you may choose not to have treatment because your day-to-day life is not significantly affected. After the menopause, fibroids often shrink, and it is likely your symptoms will either ease slightly or disappear completely.

To treat fibroids, your GP may recommend medication. However, in more severe cases, a number of surgical techniques may be considered. You should visit your GP to discuss the best treatment plan for you.

Medication for symptoms

There are medicines available that can be used to treat heavy periods, but they can be less effective the larger your fibroids are. These medications are described below.

Levonorgestrel intrauterine system (LNG-IUS)

LNG-IUS is a small, plastic device that is placed in your womb and slowly releases the progestogen hormone called levonorgestrel. LNG-IUS stops the lining of your womb from growing quickly, so that it is thinner and your bleeding becomes lighter.

Side effects associated with LNG-IUS include:

• irregular bleeding that may last for more than six months
• acne (inflamed skin on the face)
• headaches
• breast tenderness

In rare cases, LNG-IUS may also stop you having periods at all.

Tranexamic acid

Tranexamic acid tablets are taken three to four times a day throughout your period. The tablets work by helping the blood in your womb to clot, which reduces the amount of bleeding.

Tranexamic acid tablets are not a form of contraception and will not affect your chances of becoming pregnant once you stop taking them. Treatment should be stopped if your symptoms have not improved within three months.

Anti-inflammatory medicines

Anti-inflammatory medicines, such as ibuprofen and mefenamic acid, can be taken for a few days during your period and will help ease your heavy bleeding. They work by reducing your body’s production of a hormone-like substance called prostaglandin, which is linked to heavy periods.

Anti-inflammatory medicines are also painkillers, but they are not a form of contraception. Indigestion and diarrhoea are common side effects.

The contraceptive pill

The contraceptive pill is a popular form of contraception that stops an egg from being released from the ovaries to prevent pregnancy. As well as making bleeding lighter, some contraceptive pills can help to reduce period pain. Your GP will be able to provide you with further advice about contraception and the contraceptive pill.

Gonadotropin releasing hormone analogues (GnRHas)

GnRHas such as goserelin acetate are hormones that are often recommended to treat fibroids. GnRHas are given by injection and work by making your body release a small amount of oestrogen, which causes your fibroids to shrink.

GnRHas stop your menstrual cycle (period) but they are not a form of contraception. They do not affect your chances of becoming pregnant after you stop using them. 

If you are prescribed GnRHas, they can help to ease heavy periods and any pressure that is felt on your stomach. They can also help to improve symptoms of frequent urination and constipation.

GnRHas can cause a number of menopause-like side effects including:

• hot flushes
• increased sweating
• muscle stiffness
• vaginal dryness

Osteoporosis (thinning of the bones) is an occasional side effect of taking GnRHas. Your GP will be able to give you more information about this and may prescribe additional medication to minimise thinning of your bones.

GnRHas are only prescribed on a short-term basis and after treatment is stopped your fibroids may return.

GnRHas can also be used to shrink fibroids prior to having surgery to remove them. Sometimes, a combination of GnRHas and low doses of hormone replacement therapy (HRT) may be recommended to shrink your fibroids, while preventing the side effects of the menopause.

Surgery

Surgery may be considered if your fibroid symptoms are particularly severe and all forms of medication have proved ineffective.

There are several different surgical procedures used to treat fibroids. Your GP will refer you to a specialist who will be able to discuss all the options with you, including the benefits and any associated risks.

Some of these surgical procedures are explained below.

Hysterectomy

A hysterectomy is a surgical procedure to remove the womb. It may be recommended if you have large fibroids or severe bleeding.

A hysterectomy is the best way of preventing fibroids from coming back. You may want to consider it if you have fibroids that are particularly troublesome and you do not wish to have any more children.

Side effects of a hysterectomy include the possibility of early menopause and a reduction in libido (sex drive). 

Myomectomy

A myomectomy is a surgical procedure to remove the fibroids from the wall of your womb. It may be considered as an alternative to a hysterectomy, particularly for women who still wish to have children.

A myomectomy involves making a small incision (cut) in your stomach through which your fibroids are removed. This type of surgery is commonly known as keyhole surgery.

A myomectomy may not always be possible as it depends on your individual circumstances, such as the size, number and position of your fibroids.

Non-surgical treatments

As well as traditional surgical techniques to treat fibroids, there are also non-surgical treatments available. These are outlined below.

Endometrial ablation

Like a myomectomy, endometrial ablation is an alternative to having a hysterectomy and involves removing the lining of the womb. It is usually only recommended for fibroids that are near to the inner surface of the womb.

The affected womb lining can be removed in a number of ways, for example by using laser energy, a heated wire loop, microwave heating or hot fluid in a balloon.

Uterine artery embolisation (UAE)

Uterine artery embolisation (UAE) is an alternative procedure to a hysterectomy and myomectomy for treating fibroids. It may be recommended for women with large fibroids.

UAE is performed by a radiologist (a doctor who has been trained to interpret X-rays and scans). It works by blocking the blood vessels that supply blood to the fibroids, causing them to shrink.

During the procedure, a chemical is injected through a small tube (catheter), which is guided by X-ray through a blood vessel in your leg. It is carried out under local anaesthetic, which means you will be awake but the area being treated will be numbed.

Following a UAE, you will need to stay in hospital for 24 to 36 hours. When you leave hospital, you will be advised to rest for one to two weeks.

New treatments

There are also two newer techniques for treating fibroids, which use magnetic resonance imaging (MRI). They are:

• MRI-guided percutaneous laser ablation
• MRI-guided transcutaneous focused ultrasound

These techniques use MRI to guide small needles into the centre of the fibroid being targeted. Laser energy, or ultrasound energy, is then passed through the needles to destroy the fibroid. These treatment methods cannot be used to treat all types of fibroids, and the long-term benefits and risks are unknown.

Although research is still being done, some evidence suggests that this non-invasive procedure has short- to medium-term benefits when performed by an experienced clinician. However, the effects on pregnancy and those wishing to have a baby in the future are not fully known, so this should be taken into consideration.

Read the NICE guidance on MRI-guided transcutaneous focused ultrasound.

Most women do not experience any symptoms of fibroids. However, in rare cases, fibroids can cause significant complications.

Complications can occur as a result of the positioning of fibroids, and in cases where they are very large. Some possible complications are outlined below.

During pregnancy

During pregnancy, levels of the female reproductive hormone, oestrogen, can increase by as much as five times the normal amount. As fibroids are thought to develop due to high oestrogen levels, this may lead to complications with the development of the baby, or cause problems during labour.

In very rare cases, fibroids can cause miscarriage (the loss of pregnancy during the first 23 weeks). Your GP or midwife will be able to give you further information and advice if you have fibroids and you are pregnant.

Infertility

Infertility (the inability to become pregnant) may occur in cases where a woman’s fibroids are very large. Large fibroids can sometimes prevent a fertilised egg attaching itself to the lining of the womb, although this is rare.

If you have a submucosal fibroid (which grows from the muscle wall into the cavity of your womb) it may block a fallopian tube, making it harder for you to become pregnant. The ovaries (female reproductive organs) release eggs that pass down the fallopian tubes that connect the ovaries to the womb.