Uterine Fibroids (Leiomyomas)

Fibroids are common, benign growths of womb (uterine) muscle. They are present in around 1/4-5 of white women and 1/2 black women. They are most common toward the end of the reproductive years. They exist sometimes singly, but most often are multiple and range in size from microscopic to filling the whole of the lower abdomen! They are more common in obese women and those who have no children, there probably is some genetic determinant and they are less common in smokers.

Most fibroids do not cause symptoms, but overall symptomatic fibroids account for about one third of all hysterectomy operations.

What are the Different Types of Uterine Fibroids?

Fibroids are named depending upon where they lie. Those that are wholly within the muscle layer of the womb are called intramural fibroids. They typically give the uterus a globular feeling on examination (like early pregnancy). They increase overall blood flow to the uterus and if large can distort and enlargen the internal cavity, even if they don't encroach onto it.

Subserosal fibroids are those that project out from the outer surface of the uterus. They can grow quite large, but do not typically affect the size of the womb cavity. They are more likely to produce pressure symptoms than heavy periods or infertility.

Submucosal fibroids are the least common (5% of all fibroids). They project into the womb cavity and greatly disrupt its shape. They are the type most likely to cause fertility problems. Sometimes they grow into the uterus, filling it and even growing out of the cervix.

Fibroid Symptoms

The most common fibroid symptoms reported by women with fibroids are pressure symptoms and heavy periods. An enlarged womb will place pressure on the bladder giving increased urinary symptoms (eg. frequency), and can cause back ache, lower abdominal discomfort and pain on intercourse. Fibroids can cause very heavy periods, leading to iron-deficiency anaemia. They don't cause disturbance to the menstrual cycle itself - typically the bleeding is regular but much heavier than usual. The periods may be more painful than usual (called secondary dysmenorrhoea).

It is estimated that fertility problems are one of the presenting features in about 1/4 of women with fibroids. There is a well-established relationship between the presence of fibroids and lower fertility or childlessness. When compared to other causes of infertility, however, they are a relatively uncommon cause, being implicated in only 3% of couples. It may be that a delay in having children (whether voluntary or involuntary) predisposes to the development of fibroids and this is more often an association rather than a causative feature.

How are Fibroids Investigated?

Fibroids are often diagnosed and discovered on pelvic examination, where the uterus feels larger than expected with hard round lumps felt arising from the surface. Ultrasound scan can tell where the fibroids are located and give an idea of their size. Sometimes they are detected on laparoscopy (looking into the abdomen with a small telescope) or hysteroscopy (looking into the uterus with a fine telescope). Hysteroscopy is particularly useful for seeing the submucous fibroids and assessing how much of the uterine cavity is involved.

What are Fibroid Treatment Options?

If the fibroids aren't causing any symptoms and are relatively small (less than equivalent to a 14-week pregnancy) then it is quite reasonable to just observe them in the first instance. It is important to repeat a scan or examination in 6 months time to rule out rapid growth (something which would prompt removal). Women who are near the menopause will often not need surgery as they will shrink once the level of the hormone oestrogen declines.

If fertility is desired or for other reasons hysterectomy is not wished, a myomectomy can be performed. This is still major surgery, where the fibroids are individually removed and the uterus reconstructed. It has the advantage of preserving fertility and is most useful where there are one or two large fibroids. A woman must understand that haemorrhage from the operation can sometimes be significant and occasionally a hysterectomy must be performed to control bleeding. Within 20 years of myomectomy, about 1 in 4 women will undergo hysterectomy most often for recurrent symptomatic fibroids.

Hysterectomy is the definitive treatment for symptomatic fibroids. Most often this will need to be carried out via an abdominal incision, though a skilled vaginal surgeon may be able to perform a vaginal hysterectomy following medical treatment to shrink the fibroids before the operation. Most abdominal operations will be carried out via a low 'bikini-line' incision, but if the uterus is large, an 'up-and-down' vertical incision may be needed.

Submucosal fibroids which project into the uterine cavity may be removed by passing a telescope into the womb from down below and chipping away at the surface with a hot wire loop (hysteroscopic resection). This is a day-case procedure avoiding major surgery, but completion may require more than one operation.

Another option which is being developed in some areas is uterine artery embolisation. This involves a radiologist passing a very thin catheter into a blood vessel in the groin and guiding it toward one of the arteries that lead to the fibroid. The small artery is blocked off leading to shrinkage of the fibroid. Long term results of success of this treatment is not yet available and very few women have become pregnant afterwards. At present it is not widely available, but further information can be found on Dr WJ Walkers information pages.

What About Medical Treatment?

Medical or tablet treatment has a limited role in managing fibroids. There are drugs which can be used to reduce the symptoms - such as pain-killers or those which can reduce the amount of blood loss each cycle. Blood loss may be reduced by the use of the contraceptive pill. Previous reports of growth of fibroids in response to the pill probably relate to older, high dosage formulations, and use of the birth control pill may be protective against their development.

There are some treatments that can shrink fibroids, but they have the side effect of making a woman effectively menopausal, by switching off the ovary's production of hormones. If this is continued for more than 6 months, there are risks of bone-thinning oesteoporosis & heart disease, as well as the other uncomfortable symptoms of hot flushes, vaginal dryness and psychological symptoms. This treatment is most useful prior to surgery as discussed above. Alternatively it may be considered in a woman near to the menopause who is keen to avoid an operation.

What is the Success Rate After Surgery Other Than Hysterectomy?

In women undergoing myomectomy for infertility, a large review of the published data found a pregnancy rate of 40-60%, the majority conceiving in the first year after treatment. Where myomectomy is performed for heavy periods, an 80% success rate is reported. Fibroid recurrence rate at 10 years was 27% in a 1991 review of 622 patients.

Hysteroscopic resection is a more recently developed procedure and long-term follow-up of large numbers of women is not available yet. Studies published so far demonstrate an 80-90% success rate for surgery performed for heavy periods, with around 17% requiring a second operation in the following 10 years (similar to myomectomy). Pregnancy rates following resection of submucous fibroids where this is the only cause of infertility are high, at 60-70%.

Fibroids and Pregnancy

One study published in 1993 looked at 12,500 pregnancies where just under 500 women had fibroids detected during pregnancy. 88% of them were single fibroids. There was an increased risk of bleeding, pain during pregnancy and threatened premature delivery. These were more common when the size of the fibroid measured 200cm3 volume or greater and when the location of the fibroid was under the placenta. There was no increased risk of early delivery, or caesarean section. Other studies, however, do report an increased risk of early delivery.

As others have found, if attempt is made to remove the fibroids at the time of caesarean section, bleeding can be profuse and in the series above hysterectomy was needed in 1/3 of cases where this was attempted. Most people have reported a tendency towards increase in fibroid size during pregnancy and then shrinking again afterwards, but a 1988 study followed women with serial scans during pregnancy and 80% remained the same size (20% growing).

If the fibroid is located low in the uterus, it may obstruct labour increasing the risk of caesarean section, but one at the top is less likely to do so. Most don't need removal afterwards, and since it wasn't causing you any problems before, there is little reason to suspect it will do after pregnancy. If it remained large (increasing the womb size to greater than a 12-week pregnancy) then you may be offered treatment (usually surgery - myomectomy, or fibroid removal), though increasingly we are not operating on the ones that aren't causing any problems.

Pain from fibroids occurs because of something called 'red degeneration'. Pain-killers are all that's needed, and to exclude other causes of pain during pregnancy.

Cancerous Change in Fibroids

This is something that can happen, but is extremely rare. It is thought to happen in about 0.1%, from published studies. Many cases of fibroids are not diagnosed, so this figure must be an overestimation. It is 10 times more common in a woman in her 60's than one in her 40's and usually causes symptoms. Rapid enlargement of a fibroid in a post-menopausal woman would arise suspicion and prompt surgical removal. As mentioned above, fibroids are common - most women know someone who has them, yet most gynaecologists would see cancerous change once or twice in their lifetime practice.  Find out more about the risks of cancer and fibroids.

Also check out our articles on other kinds of fibroids like Breast Fibroids.

Women who experience iron-deficiency due to increased menstrual bleeding can regulate their iron levels with a simple iron supplement. A doctor can prescribe the appropriate dosage.

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