Uterine Fibroids Content from the guide to life, the universe and everything

Uterine Fibroids

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Fibroids are overgrowths of muscular and connective tissue that commonly occur in the wall of the uterus, but may also appear in the cervix1, Fallopian tubes2 and surrounding ligaments. They are a form of benign tumour3 that affects around one in five women at some time in their lives, with around one in 20 having fibroids at any one time. The cause of fibroids is unknown, though they are thought to arise from a series of 'seedlings' scattered across the uterus, and are dependent upon the high levels of oestrogen found in women of reproductive age. Symptoms are dependent upon the location and size of the fibroids, and may include abdominal discomfort, vaginal bleeding and unusually heavy periods. Several forms of treatment are available, ranging from medical treatments to removal of either the fibroids (myomectomy) or the entire uterus (hysterectomy).

There are four types of fibroid, depending upon their location:

  • Intramural fibroids grow within the muscular wall of the uterus (myometrium) and are the most common type.

  • Subserosal fibroids grow outwards from the uterus, and thus have the space to become rather large.

  • Submucosal fibroids grow just beneath the inner lining of the uterus.

  • Cervical fibroids grow in the wall of the cervix, at the neck of the uterus.

Fibroids as large as footballs and weighing up to 10kg have been recorded. Fortunately, most fibroids are diagnosed and treated long before they become this large. For those who might confuse them with dermoid cysts of the ovaries, it is worth mentioning that fibroids do not contain hair or teeth.

Symptoms and Diagnosis

Many smaller fibroids do not cause any symptoms and are only discovered incidentally during a routine examination. On the other hand, large fibroids can cause discomfort and swelling of the abdomen, and may cause backache, constipation, and painful or frequent urination due to increased pressure in the pelvis. Submucosal fibroids can cause heavy menstruation that leads to anaemia, and may also extend into the uterus on stalks and cause persistent bleeding. Cervical fibroids may cause pain on intercourse (dyspareunia) and bleeding afterwards. Fibroids can sometimes interfere with fertility, and are one cause of repeated miscarriage.

The change in appearance of the abdomen and bleeding caused by some fibroids can be very socially debilitating:

...the thickest night-time sanitary towels are not enough, you can't go anywhere without a change of clothes and a few towels, in fact it's best not to leave the house at all because the bleeding can be horrendous and alarmingly sudden.
- an h2g2 Researcher.

This is made worse by the fact that women tend to avoid talking about such a sensitive matter unless they are assured that the disease is common and not particularly stigmatising. Concerns about a woman's potential to bear children in the future should be raised with a good gynaecologist.

Some fibroids can be diagnosed easily following examination of a 'knobbly' uterus via the abdomen and vagina. However, in some cases a smooth, curved mass may be felt, leading to the possibility of alternative diagnoses such as ovarian tumour or pregnancy. In all cases, an ultrasound scan of the pelvis can be used to confirm the presence of fibroids. In the case of fibroids that cause bleeding or changes in menstruation, hysteroscopy4 is performed to rule out alternative, sinister causes.


Although fibroids are present in around one in 200 pregnancies, most are small enough not to cause any problems. However, the increased levels of oestrogen during pregnancy may cause increased growth of the fibroids. In some cases, a fibroid may grow faster than its blood supply, causing the death and degeneration of parts of the tumour. This produces symptoms of pain and fever, which are best treated using painkillers. Fibroids may alter the shape of the uterine cavity, leading to an increased risk of miscarriage, premature labour and abnormal positioning of the foetus inside the uterus. A fibroid in the lower part of the uterus may also obstruct birth, occasionally leading to the need for a caesarean section. Finally, fibroids can also interfere with the contraction of the uterus, thus leading to excessive bleeding after birth (postpartum haemorrhage).


  • Watch and Wait
  • The simplest option for treatment of fibroids is to wait and rescan the individual at regular intervals. This can be done provided the fibroids are smaller than a 14-week pregnancy, symptomless, slow-growing and will not interfere with conception or childbirth.

  • Treatment of Heavy Periods
  • Heavy menstruation may be treated using anti-inflammatory drugs, tranexamic acid, the oral contraceptive pill, the intra-uterine system, and endometrial ablation. Anti-inflammatory drugs help by inhibiting the production of prostaglandins, thus reducing the pain and heaviness of periods. Tranexamic acid also helps reduce the heaviness of periods, in this case by increasing the degree of clotting that takes place during menstrual bleeding. The oral contraceptive pill replaces periods with withdrawal bleeding, and in some cases also improves period pain. The intra-uterine system, which consists of a small piece of plastic placed in the uterus which releases progesterone, also reduces the heaviness of menstrual bleeding. Endometrial ablation, in which the lining of the uterus is destroyed using one of several techniques, is sometimes used as an alternative to hysterectomy.

  • Shrinking the Fibroids
  • Fibroids may sometimes be treated in the short term using a GnRH agonist, which causes the body to produce less oestrogen and thus causes the fibroids to shrink. The reduction in oestrogen levels also helps with heavy menstrual bleeding. Although GnRH agonists do not have a permanent effect on fertility, they can cause menopause-like symptoms such as hot flushes, mood disturbances and, in some cases, bone loss. This can be countered to a certain extent through the use of hormone replacement therapy alongside the GnRH agonist. Uterine artery embolisation, a novel treatment that involves blocking off one of the vessels supplying the uterus via a catheter inserted into a large artery, has also been shown to cause large fibroids to shrink.

  • Removing the Fibroids
  • In cases where fibroids are large, cause symptoms, may interfere with fertility or pregnancy, or cause distress, they can be removed surgically. In women who wish to retain the ability to reproduce, the fibroids may be removed by myomectomy, with a GnRH agonist being given before surgery to shrink the fibroids. The procedure may be performed by laparotomy or laparoscopy5 depending upon the size of the fibroids. In both cases, the surgeon cuts out all detectable fibroids and then repairs the uterus. Unfortunately, myomectomy is occasionally complicated and needs to be converted to a hysterectomy, a matter which should always be discussed before the operation. Around 40% of women are successful in conceiving following a myomectomy, though around 5% of all those treated have a recurrence of their fibroids at a later date. In the case of women who do not wish to reproduce, a hysterectomy may be performed instead.

1The neck of the womb.2Also known as oviducts, these are a pair of tubes that lead from the ovaries to the uterus.3At least 99% of fibroids will never spread beyond their initial site.4Insertion of a camera into the uterus via the vagina.5Laparotomy involves opening the abdomen through a large surgical incision, whereas laparoscopy involves the use of several small 'keyhole' cuts through which a camera and surgical instruments can be passed.

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