Fibroids are common, non-cancerous growths of womb (uterine) muscle. They are present in around 1 in 4 to 5 of white women and 1 in 2 women of Afro-Caribean origin. 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 if you are overweight or have no children, there probably is some genetic determinant and they are less common in smokers (but this is definitely not a reason to start or continue smoking!)
Most fibroids do not cause any problems, but overall the worse fibroids account for about one third of all hysterectomy operations.
What are the different types?
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 bulky, rounded feeling on examination (as in early pregnancy). They increase overall blood flow to the uterus and if large can distort and enlarge 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 usually affect the size of the womb cavity. They are more likely to produce pressure symptoms than heavy periods or infertility.
Submucous fibroids are the least common. They grow into the womb cavity and can 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.
What symptoms can they cause?
The most common complaints of women with fibroids are pressure symptoms and heavy periods. An enlarged womb will place pressure on the bladder giving increased urinary symptoms (such as needing to pass water all the time), and can cause back ache, lower abdominal discomfort and pain on intercourse. Fibroids can cause very heavy periods, leading to anaemia and iron deficiency. They don't normally change the pattern of the menstrual cycle itself - usually the bleeding is regular but much heavier than usual. The periods may be more painful than usual (known in medical terminology as secondary dysmenorrhoea).
There is a well-established relationship between the presence of fibroids and reduced fertility or childlessness. 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 cause-and-effect situation.
How are they investigated?
Often they are just 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 within the uterus 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 they have grown inside the uterus.
What are the 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 make one suggest removing them). Women who are near the menopause won't usually need surgery as they will shrink once the level of the hormone oestrogen declines.
If they do need to be removed and future pregnancies are on the cards, or for other reasons hysterectomy is not wished, a myomectomy can be performed. This is still major surgery, where the fibroids are individually removed. 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. After myomectomy, around 1 in 4 women will still eventually end up needing a hysterectomy, most often for recurrent symptomatic fibroids.
Hysterectomy is obviously a final treatment for fibroids that are causing symptoms. 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.
Submucous 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 the success of this treatment is not yet available.
What about medical treatment?
Medical or tablet treatment has a limited role in treating 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 (cyclokapron). 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 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 osteoporosis and heart disease, as well as the other uncomfortable symptoms of hot flushes, vaginal dryness and psychological symptoms. This treatment is most useful before 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 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 was larger and when the location of the fibroid was under the placenta. There was no increased risk of early delivery, or caesarean section. Other research, however, does not report an increased risk of early delivery.
If attempt is made to remove the fibroids at the time of caesarean section, bleeding can be heavy and in the series above hysterectomy was needed in 1/3 of cases where this was attempted. Some fibroids increase in size during pregnancy and then shrinking again afterwards.
If the fibroid is located low in the uterus, it may obstruct labour increasing the risk of caesarean section, but one at the top of the womb is less likely to do this. Most fibroids don't need removal afterwards, and if they weren't causing any problems beforehand, there is little reason to suspect it will do after pregnancy. If it remained large then you may be offered treatment, though increasingly we don't suggest surgery unless they cause problems.
Pain from fibroids occurs because of something called 'red degeneration'. Pain-killers are all that's needed, and to rule out other more important 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.