Fibroids are non-cancerous tumours that grow in or around the womb (uterus). The growths are made up of muscle and fibrous tissue and vary in size.
They are sometimes known as uterine myomas or leiomyomas.
Many women are unaware they have fibroids as they do not have any symptoms. Women who do have symptoms may experience:
heavy periods or painful periods
tummy (abdominal) or lower back pain
a frequent need to urinate
pain or discomfort during sex
In rare cases, fibroids can cause significant complications, such as infertility and problems during pregnancy.
Seeing your GP
As they commonly cause no symptoms, fibroids are sometimes diagnosed by chance during a routine gynaecological examination, test or scan.
However, you should see your GP if you have persistent symptoms of fibroids so they can investigate possible causes.
If your GP thinks you may have fibroids, they will usually refer you for an ultrasound scan to confirm the diagnosis.
Why fibroids develop
The exact cause of fibroids is unknown. However, they are linked to the 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) when oestrogen levels are at their highest, and they tend 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).
Who is affected?
Fibroids are common, with more than 40% of women developing them at some point in their life. They most often occur in women aged 30 to 50 years.
Fibroids are thought to develop more frequently in women of African Caribbean origin. It is also thought they occur more often in overweight or obese women because being overweight increases the level of oestrogen in the body.
Women who have had children have a lower risk of developing fibroids, and the risk decreases further the more children you have.
Types of fibroids
Fibroids can grow anywhere in the womb and vary in size considerably. Some can be the size of a pea, whereas others can be the size of a melon.
The main types of fibroids are:
intramural fibroids – the most common type of fibroid, they develop in the muscle wall of the womb
subserosal fibroids – fibroids that develop outside the wall of the womb into the pelvis and can become very large
submucosal fibroids – fibroids that develop in the muscle layer beneath the inner lining of the womb and grow into the middle of the womb
In some cases, subserosal or submucosal fibroids are attached to the womb with a narrow stalk of tissue. These are known as pedunculated fibroids.
If fibroids do not cause symptoms, treatment is not needed. They will often shrink and disappear without any treatment over time, particularly after the menopause.
If you do have symptoms caused by fibroids, medication to help relieve the symptoms will usually be recommended first.
If these medications are ineffective, surgery or other less invasive procedures may be recommended.
Symptoms of fibroids
Many women are unaware they have fibroids because they do not have any symptoms. Around one in three women with fibroids experiences some symptoms.
If your fibroids do cause symptoms, you may experience one or more of the problems outlined below.
In rare cases, further complications caused by fibroids can affect pregnancy or cause infertility.
See complications of fibroids for more information about this.
Heavy or painful periods
Fibroids do not disrupt the normal menstrual cycle (periods), but can cause heavy, prolonged or painful bleeding.
If you have heavy periods (menorrhagia), it does not necessarily mean there is anything seriously wrong. However, it can be stressful and significantly disrupt your everyday life.
In some cases, heavy periods can cause iron deficiency anaemia, resulting in symptoms such as tiredness, lethargy and shortness of breath.
If you have fibroids, particularly larger ones, you may experience discomfort or bloating (swelling) in your tummy. 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 your vagina or cervix (neck of the womb), you may experience pain or discomfort during sex.
If your GP suspects fibroids, they will usually carry out a pelvic examination to look for any obvious signs.
They may also refer you to a local hospital for further tests outlined below to confirm a diagnosis or rule out other possible causes of your symptoms.
Sometimes fibroids are only discovered during routine gynaecological (vaginal) examinations or tests for other problems, as they often don't cause any symptoms.
One of the main tests carried out to diagnose fibroids is an ultrasound scan. This is a painless scan that uses a probe to produce high frequency sound waves to create an image of the inside of your body.
There are two types of ultrasound scan that can be used to help diagnose fibroids. These are:
an abdominal ultrasound scan – where the ultrasound probe is moved over the outside of your tummy (abdomen)
a transvaginal ultrasound scan – where the ultrasound probe is inserted into your vagina
Images produced by these scans are transmitted to a monitor so your doctor can see if there are any signs of fibroids.
If an ultrasound scan suggests fibroids, you may be referred to a gynaecologist (a specialist in the female reproductive system) for tests described below.
A hysteroscopy involves inserting a small telescope (hysteroscope) into your vagina so your doctor can examine the inside of your womb.
It can be carried out under local anaesthetic or general anaesthetic, so you won't feel any pain during the procedure.
A hysteroscopy is most often used to look for fibroids within your womb (submucosal fibroids).
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.
During a laparoscopy a surgeon makes a small incision in your abdomen, passes the laparoscope through the incision, and studies the organs and tissues inside the abdomen or pelvis. General anaesthetic is used, so you will be asleep during the procedure.
A laparoscopy can be used to look for fibroids outside your womb (subserosal fibroids) or fibroids in the layer of muscle surrounding the womb (intramural fibroids) that have affected its size and shape.
In some cases, a small tissue sample called a biopsy may be removed during a hysteroscopy or laparoscopy for closer examination under a microscope.
Treatment may not be necessary in cases where there are nosymptoms of fibroids, or where symptoms are minor and your everyday activities are not significantly affected.
Fibroids often shrink after the menopause, and your symptoms will usually either ease slightly or disappear completely.
If you have fibroids that need treatment, your GP may recommend medication to help relieve your symptoms. However, you may need to see a gynaecologist (specialist in the female reproductive system) for further medication or surgery if these are ineffective.
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 reduce 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 placed in your womb that slowly releases the progestogen hormone levonorgestrel. LNG-IUS stops the lining of your womb from growing quickly, so 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
in rare cases, no periods at all (absent periods)
LNG-IUS also acts as a contraceptive, but does not affect your chances of getting pregnant after you stop using it.
If LNG-IUS is unsuitable (for example, if contraception is not desired), tranexamic acid tablets may be considered. These tablets work by helping the blood in your womb to clot.
Tranexamic acid tablets are taken three times a day during your period for up to four days. Treatment should be stopped if your symptoms have not improved within three months.
Tranexamic acid tablets are not a form of contraception and will not affect your chances of becoming pregnant.
Possible side effects include indigestion and diarrhoea.
Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and mefenamic acid, can be taken three or four times a day from the first day of your period until bleeding stops or reduces to satisfactory levels.
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 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 reduce period pain.
Your GP can provide you with further advice about contraception and the contraceptive pill.
Norethisterone is a type of man-made progestogen (one of the female sex hormones) that can help reduce heavy periods. It is usually taken as a daily tablet from days 5 to 26 of your menstrual cycle, counting the first day of your period as day one.
Oral norethisterone works by preventing your womb lining growing quickly. It is not a form of contraception, although it can reduce your chances of conceiving while you are taking it.
The side effects of oral norethisterone can be unpleasant, and include weight gain, breast tenderness and short-term acne.
Progestogen is also available as an injection to treat heavy periods. This medication works by preventing the lining of your womb growing quickly.
This form of progestogen can be injected once every 12 weeks for as long as treatment is required.
Common side effects of injected progestogen include:
premenstrual symptoms, such as bloating, fluid retention and breast tenderness
Injected progesterone also acts as a contraceptive. It does not prevent you becoming pregnant after you stop using it, although there may be a delay after you stop taking it before you are able to get pregnant.
Medication to shrink fibroids
If you are still experiencing symptoms related to fibroids despite treatment with the medications outlined above, your GP can refer you to a gynaecologist. They may prescribe medication called gonadotropin releasing hormone analogues (GnRHas) to help shrink your fibroids.
GnRHas, such as goserelin acetate, are hormones given by injection and work by making your body release a small amount of the hormone oestrogen, which causes your fibroids to shrink.
GnRHas stop your menstrual cycle (period), but 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 also help improve symptoms of frequent urination and constipation.
Sometimes GnRHas are used to shrink fibroids prior to surgery to remove them.
GnRHas can cause a number of menopause-like side effects, including:
Sometimes a combination of GnRHas and low doses of hormone replacement therapy (HRT) may be recommended to prevent these side effects.
Osteoporosis (thinning of the bones) is an occasional side effect of taking GnRHas. Your GP can give you more information about this, and may prescribe additional medication to minimise thinning of your bones.
GnRHas is only prescribed on a short-term basis (a maximum of six months at a time). Your fibroids may grow back to their original size after treatment is stopped.
Surgery may be considered if your fibroid symptoms are particularly severe and medication has been ineffective.
There are several different procedures used to treat fibroids. Your GP will refer you to a specialist, who will discuss options with you, including benefits and any associated risks.
The main procedures used to treat fibroids are outlined below.
A hysterectomy is a surgical procedure to remove the womb. It is the most effective way of preventing fibroids coming back.
It may be recommended if you have large fibroids or severe bleeding and you do not wish to have any more children.
There are a number of different ways a hysterectomy can be carried out, including through the vagina or through a number of small incisions in your abdomen (tummy).
Depending on the technique used, the procedure can be carried out under local anaesthetic (where you will be numbed from the waist down) or general anaesthetic (where you are unconscious during the procedure).
You will usually need to stay in hospital for a few days after a hysterectomy. It takes about six to eight weeks to fully recover, during which time you should rest as much as possible.
Side effects of a hysterectomy can include early menopause and areduction in libido (sex drive).
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.
However, a myomectomy is not suitable for every type of fibroid. Your gynaecologist will be able to tell you if the operation is suitable for you based on things such as the size, number and position of your fibroids.
Depending on the size and position of the fibroids, a myomectomy may involve making either a number of small incisions (cuts) in your tummy (keyhole surgery) or a single larger incision (open surgery).
Myomectomies are carried out under general anaesthetic and you usually need to stay in hospital for a few days after the procedure. Like a hysterectomy, you will normally be advised to rest for several weeks while you recover.
Myomectomies are generally an effective treatment for fibroids, although there is a chance the fibroids will grow back and further surgery will be needed.
As well as traditional surgical techniques to treat fibroids, there are also non-surgical treatments available. These are outlined below.
Uterine artery embolisation (UAE)
Uterine artery embolisation (UAE) is an alternative procedure to a hysterectomy or myomectomy for treating fibroids. It may be recommended for women with large fibroids.
UAE is performed by a radiologist (a doctor trained to interpret X-raysand scans). It involves blocking the blood vessels that supply 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.
You will usually need to stay in hospital a day or two after UAE. When you leave hospital, you will be advised to rest for one to two weeks.
Although it is possible to have a successful pregnancy after UAE, the effects of the procedure on fertility and pregnancy are generally uncertain. The procedure should therefore only be carried out after a detailed discussion with your doctor about the potential risks, benefits and uncertainties.
Endometrial ablation is a relatively minor procedure that involves removing the lining of the womb. It is mainly used to reduce heavy bleeding in women with fibroids, but it can also be used to treat small fibroids in the womb lining.
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.
The procedure can be carried out either under local anaesthetic orgeneral anaesthetic. It is fairly quick to perform, taking around 20 minutes, and you can often go home the same day.
You may experience some vaginal bleeding and tummy cramps for a few days afterwards, although some women have bloody discharge for three or four weeks.
Some women have reported experiencing more severe or prolonged pain after having endometrial ablation. In this case, you should speak to your GP or a member of your hospital care team who may be able to prescribe a stronger painkiller.
While it may still be possible to get pregnant after having endometrial ablation, the procedure is not recommended for women who want to have more children. This is because the risk of serious problems, such as miscarriage, is high.
More information about endometrial ablation is available from the Royal College of Obstetricians and Gynaecologists (RCOG), who have produced a leaflet called Information for you after an endometrial ablation (PDF, 3.75Mb).
Hysteroscopic resection of fibroids is a procedure that involves using a thin telescope called a hysteroscope and a number of small surgical instruments to remove fibroids. The procedure is carried out through the vagina, so no incisions are needed.
The procedure can be used to remove small fibroids located inside the womb (submucosal fibroids) and is suitable for women who wish to have children in the future.
Hysteroscopic resection of fibroids is often performed under a general anaesthetic, although local anaesthetic may also be used. You can usually go home the same day the procedure is carried out.
You may experience stomach cramps after the procedure, but these should only last a few hours. There may also be a small amount of vaginal bleeding, which should stop within a few weeks.
As well as the procedures outlined above, there are two newer techniques for treating fibroids that 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. As these procedures are relatively new, they are not yet widely available in the UK.
Although research is still being done, some evidence suggests 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 guidance on MRI-guided transcutaneous focused ultrasound and MRI-guided percutaneous laser ablation from the National Institute for Health and Care Excellence (NICE).
Complications of fibroids
Although most women do not experience any symptoms of fibroids, they can cause significant problems in rare cases.
The likelihood of complications occurring depends on things such as the position of the fibroids and their size. Some main complications are outlined below.
Problems during pregnancy
The presence of fibroids during pregnancy can sometimes lead to problems with the development of the baby or difficulties during labour.
Specifically, women with fibroids may experience tummy (abdominal) pain during pregnancy and there is a risk of premature labour. If large fibroids block the vagina, a caesarean section (delivery through a cut in the tummy and womb) may be necessary. In 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 are pregnant.
Infertility (the inability to become pregnant) may occur in cases where a woman's fibroids are large. Large fibroids can sometimes prevent a fertilised egg attaching itself to the lining of the womb or prevent sperm reaching the egg, 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 fallopian tubes are the tubes that connect the ovaries (where the egg is released) to the womb.