What are fibroids?

Fibroids (also known as leiomyomas, myomas or fibromyomas) are benign (non-cancerous) growths in the muscle of the uterus. They occur most commonly in women of child-bearing age.

As fibroids don’t always cause symptoms it is not clear how common they are, but studies suggest that as many as 3 in 4 women will have them at some stage in their lives.

The growth of fibroids appears to be affected by the female hormones oestrogen and progesterone. They are found more frequently in women who have a family history of fibroids, are obese, have never been pregnant or have had few pregnancies. They are also more common in women who have not taken the oral contraceptive pill (‘the pill’) over a prolonged period.

Fibroids can be categorised into 3 groups, depending on where they grow.

  • Submucosal — just underneath the inner lining of the uterus.
  • Intramural — within the wall of the uterus.
  • Subserosal — on the outside of the uterus.

They can vary widely in size, from 1 mm to more than 20 cm in width. Fibroids tend to shrink in women who have passed menopause.

Fibroid symptoms

While many women will have no symptoms, fibroids can cause:

  • heavy periods;
  • prolonged periods;
  • bleeding between periods;
  • pain or a feeling of pressure in the pelvic area;
  • period pain;
  • pain in the lower back;
  • pain during sex;
  • constipation or difficult bowel movements;
  • difficulty urinating or frequent urination.

If periods are heavy or prolonged this may lead to anaemia.

Fibroids and pregnancy

Occasionally, fibroids are associated with difficulty conceiving, miscarriage and premature birth. In these cases, removing the fibroids may be recommended.

Diagnosis of fibroids

As they don’t always cause symptoms, fibroids are sometimes only picked up on a routine gynaecological examination.

If you have symptoms suggestive of fibroids, your doctor will perform a pelvic examination to see if the uterus feels enlarged or irregular.

An ultrasound scan can then be used to confirm the diagnosis. Sometimes other investigations are also used, such as hysteroscopy, where a small telescope is passed through the cervix enabling the doctor to see inside the uterus.

Fibroid treatments

There are a number of different options for the treatment of fibroids, including both medical and surgical treatments. Some of these include:

  • Watchful waiting — if the fibroids are not causing any problems, a wait-and-see approach may be adopted, where your doctor will monitor the fibroids over time.
  • Hormonal medicines — these may be used to shrink down the fibroids or reduce the amount of bleeding or pain. Some hormonal medicines can be used to reduce the size of fibroids before having them surgically removed.
  • Surgery — there are several different types of surgical treatment, including myomectomy (where only the fibroids are removed, leaving the uterus in place) and hysterectomy (where the uterus itself is removed).
  • Uterine artery embolisation — this involves the injection of small particles into the artery to the uterus to block off the blood supply to the fibroids, causing them to shrink.
  • MRI-directed ultrasound technique — a new technique that uses MRI (magnetic resonance imaging) to visualise the fibroids which are then destroyed by focused, high-frequency, high-energy sound waves (ultrasound).

Your doctor can advise you as to which options are available for treatment in your particular case.

Last Reviewed: 16 March 2011

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1. Uterine fibroids (updated 11 Jun 2011). (accessed Dec 2011).
2. Lethaby A, Vollenhoven B. Fibroids (uterine myomatosis, leiomyomas). Clinical Evidence [online] 2011 [cited Jan 11]. URL: (accessed Dec 2011).
3. Health for Women. Fibroids (updated 4 Feb 2011). (accessed Dec 2011).


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