Fibroids are benign (non-cancerous) tumors of the muscle of the womb. They are also called myomata and leiomyomata.

Incidence

Fibroids are very common. Up to one in three women of reproductive age have fibroids.

Age

Fibroids tend to shrink in the menopause and grow during the reproductive age. Therefore, they are most common in women aged 15 to 50.

Racial variations

Fibroids are more common in afrocarribean women.

Predisposing factors

The causes of fibroids is unknown. It is known that they grow with certain hormones such as oestrogens. They also grow with treatment from exogenous hormones tamoxifen and progesterones. More recently, two genes have been associated with fibroid growth. These are called HMGI(C) and HMCI(Y).

Anatomy of fibroids

Fibroids are classically described as being in one of three places. Subserous fibroids are on the surface of the uterus. If subserous fibroids are on a stalk they are classically described as being pedunculated. If the fibroid is within the muscle of the womb it is classically described as being intramural. Fibroids that project into the cavity of the uterus are described as being submucous.

Fibroids can vary in size and number. Some women may have fibroids which are very small and only a few millimeters in size. Other women can have fibroids that are so large that they fill most of the abdominal cavity. Some women have only one fibroid and other have many.

The position of fibroids on the womb can also be important sometimes. Those in the side of the womb in the fold of tissue that attaches to the pelvic sidewall are called broad ligament fibroids. These often have a large blood supply and can be hazardous to remove. Those that are attached to the neck of the womb (cervix) are called cervical fibroids and can occasionally interfere with labour in pregnant women.

Clinical features

Most fibroids are assymptomatic. The most common and important problems consist of mass symptoms, pain, menstrual symptoms, fertility problems, cancerous change, and leiomyomatases..

Mass symptoms occur due to the bulk of the fibroids in the tummy and pelvis. They can present as an unsightly mass that may even look like a pregnant uterus. In addition to this they can cause problems as a result of pressure on other structures in the pelvis such as the bladder and rectum.

Pain can occur due to degeneration of the fibroid. This is more common in pregnancy. Degeneretion occurs when the fibroids gorws out of it's blood supply. Sometimes women with fibroids get bad period pains (dysmenorrhoea). This is probably due to additional levels of a substance called prostaglandin that can be related to spasm in the vessels of the womb during menstruation.

Menstrual symptoms. Fibroids can cause heavy periods (menorrhagia). This is probably related to increase in the surface area of the womb caused by the fibroids. Submucous fibroids give the greatest problems with heavy periods.

Fertility problems. The exact relationship between fibroids, infertility, and miscarriage is controversial. There may be a relationship although this is unproven. Excision of submucous fibroids is known to improve the success rate of some fertilitity treatments.

Cancerous change in fibroids is rare. It is thought to occur in about 1 in 500 cases. When this occurs, the fibroid develops into something called a leiomyosarcoma.

Leiomyomatoses. These are a series of very rare conditions where fibroids form in places other than the womb and can sometimes spread like a cancer. They are often stimulated by oestrogens.

Investigations

Once a doctor has taken a history and examined a patient, a number of tests are usually performed. It is normal to have an ultrasound scan. This details the exact number and location of the fibroids. A more detailed test is an MRI scan which can also characterise the inside of the fibroids.

Sometimes is it necessary to perform a test called a hysteroscopy to look at fibroids inside the cavity of the womb and occasionally a laparoscopy is required to see if there are other causes for any pain. It is also usual to have blood tests to look for anaemia and clotting problems in a woman with heavy periods (menorrhagia).

Treatment

Treatment can either be empirical or directed at the fibroid itself. Empirical treatment is treatment of the symptoms such as pain killers for pain. Common treatments for heavy periods include the pill (which also regulates the periods), antithrombotic and fibrinolytic drugs (such as a drug call tranexamic acid), the intrauterine system, and progesterones.

Treatments directed at the fibroids can be medical or invasive. The most common medical treatment for fibroids is a class of drug called GnRH analogues. These are drugs that shrink the fibroids by producing a medical menopause. They can also cause hot flushes and night sweats as a result. They can only be used for six months as they are associated with osteoporosis but are sometimes used to treat fibroids prior to surgery or in women who are in their fifties and therefore approaching their natural menopause. Newer studies have looked at giving GnRH analogues with a low dose of HRT to allow it to be given for longer.

The mainstay of surgical treatment is myomectomy and hysterectomy. Myomectomy is the removal of the fibroid and is more suitable for patients who wish to preserve their fertility and have a smal number of large fibroids. Hysterectomy is more suitable for women who have completed their familty and have a large number of small fibroids. Women with submucous fibroids may have an operation called transcervical resection of a fibroids (TCRF).

A number of newer techniques now exist. These include laparoscopic uterine artery ablation, uterine artery embolisation, cryomyolisis, and LASER myolysis. Most of these are still in their experimental form and more information is becoming available on a regular basis.