Uterine fibroids, medically termed leiomyoma, fibromyoma or myoma but commonly known as fibroids, are benign (noncancerous) tumors that grow within the muscular layer of the uterus. Fibroids are composed of muscle and fibrous tissue, which give them a firm texture.
Fibroids are commonest benign tumors in women and mostly affect them in their middle or late reproductive years (over the age of 30), although some young women in their 20s also develop fibroids. These tumors usually come in multiples (can be up to a hundred), and can vary hugely in size - from tiny pea-sized to larger than a melon.
The types of fibroids are classified according to the location where they grow within the uterus. There are mainly three types of fibroids:
- Submucous fibroids: Fibroids that grow towards or just beneath the inner lining of uterus (endometrium).
- Intramural fibroids: Fibroids that grow deep within the muscular wall of uterus.
- Subserous fibroids: Fibroids that grow towards or just beneath the outer layer of uterus (perimetrium).
Figure 1: Types of Fibroids.
The actual cause of fibroid is not completely known. Factors such as hereditary, race, and oestrogen level, however, are conclusively linked to the disease.
It is found that many women with fibroids have a family history of the disease too. It is believed that fibroid arises from the mutation of a single muscle cell, which exists from birth.
Researchers have suggested that women with African-American ethnicity are 2-3 times more likely than other women to develop uterine fibroids. Although the actual reason behind the heightened likelihood is unknown, it has been speculated that the genetic predisposition could play a role in it, since it is common for African-American women to develop fibroids at a younger age. Besides, they tend to have multiple and large-sized fibroids.
- Oestrogen level
Many women who develop fibroids are also found to have elevated oestrogen level. While it is unclear how oestrogen contributes to the origin of the disease, it has been confirmed that fibroids do depend on the hormone to grow, just like endometriosis. This also explains why some women experience worse symptoms of fibroid during perimenopause (menopause transition years), as their oestrogen levels are abnormally high at this stage. The symptoms, however, are settled down naturally after menopause due to significant decline in oestrogen levels. Under oestrogen deficiency, the fibroids usually shrink, and sometimes disappear without treatment.
Signs and Symptoms
Many women with fibroids do not experience any unusual signs or symptoms and mostly only discover the fibroids' existence incidentally during a routine pelvic or ultrasound examination. Nevertheless, appearance of symptoms is certainly possible and can be highly troubling sometimes. The most common symptoms of fibroids are as follows:
- Heavy and prolonged menstrual bleeding
Women with fibroids are likely to experience abnormally heavy and prolonged (7 or more days) menstrual bleeding which can lead to iron-deficiency anaemia. This symptom is widely believed to be caused by the inability of uterus muscle to contract effectively to reduce menstrual flow, due to the presence of fibroids within the muscular wall of the uterus.
- Pelvic pressure
Women with large fibroids may feel a sense of fullness or pressure in the pelvic area, as the fibroids press against the surrounding organs, such as bladder and rectum. These pressures usually prevent the organs from functioning normally and may even damage the organs. The symptoms of these pressures are as follows:
- Difficulty in urinating
When the fibroid presses on the bladder, the bladder capacity is reduced. Consequently, the subject may have the urge to urinate more frequently or feel incomplete bladder emptying. In rare cases where the urethra is blocked, the subject will experience acute urinary retention (sudden inability to urinate).
- Constipation due to pressure on rectum.
- Dilation of kidney with urine (hydronephrosis)
Occasionally the fibroid presses on the ureter and obstructs the passage of urine from the kidney to the bladder. The urine will start accumulating behind the obstruction and eventually distend the entire kidney. This is known as hydronephrosis and can result in urinary tract infection and/or even permanent damage of the kidney.
- Difficulty in urinating
- Pelvic pain
There are a few reasons that fibroids can cause pain in pelvic area:
- Fibroid degeneration
When a fibroid grows to a size that its blood supply is no longer sufficient, i.e. the blood can no longer reach the fibroid's central part, it will start to degenerate from inside. In other words, the muscle tissue that makes up the fibroid dies upon occurrence of oxygen deprivation. The process will cause severe pain that usually lasts for several days to a week or more.
- Twisted peduncle
When a pedunculated fibroid becomes twisted, it can cause excruciating pain to the sufferer that an immediate surgery to remove the fibroid is required. Another situation is that the twisting has blocked the essential blood supply to the fibroid, resulting in fibroid degeneration which is very painful itself.
- Fibroid infection
Sometimes but rarely, a degenerating or dying fibroid can cause painful infection to the surrounding uterine tissue.
- Malignant change in fibroid
Very rarely (1-in-1000 chance), fibroid evolves into malignant (cancerous) tumor called leiomyosarcoma. When the malignant tissue starts to invade the surrounding uterine tissue, it can result in intense pelvic and abdominal pain, which may be accompanied by abnormal vaginal bleeding.
- Fibroid degeneration
Fibroids growing in the Fallopian tubes can compress and block the passage of the egg and sperms, making fertilization impossible to occur. Also, fibroids growing within the muscular wall of uterus may severely distort the uterine cavity, especially the endometrium (the lining of uterus) and interfere with the blood supply to it, making implantation difficult or impossible.
- Pelvic examination
The fibroids of asymptomatic patients are usually discovered during their routine pelvic examination, when their gynaecologist can feel some round and lumpy masses in their lower abdomen. Anyhow, presence of fibroids cannot be confirmed via pelvic examination alone as other diseases, for example, adenomyosis or ovarian cysts (if lumps are felt on the sides of lower abdomen) can be mistaken for fibroids or the other way round. Other assessment techniques such as reviewing patient's family medical history, ultrasound scanning and magnetic resonance imaging (MRI) are required to corroborate the diagnosis.
- Family medical history
Since fibroids tend to run in families, patient's family medical history is significant in helping the gynaecologist to determine the likelihood of fibroids.
- Ultrasound scanning
Most fibroids are easily detectable with ultrasound. The scanning can be performed either abdominally or transvaginally (through the vagina), but the latter is able to provide greater clarity of the size and location of each fibroid because the probe is closer to the uterus. Usually, the ultrasound results combined with the findings from pelvic examination are sufficient to diagnose fibroids.
- Magnetic resonance imaging (MRI)
Sometimes an MRI may be required for definite confirmation. MRI is so far the most accurate diagnostic tool for fibroids. It provides much more detailed image of the fibroids than ultrasound, allowing the gynaecologist to determine the exact number of fibroids, size and position of each fibroid, and the degree of anatomical distortion of the uterus and surrounding organs caused by the fibroids.
Hysteroscopy is a technique that allows the gynaecologist to directly visualize patient's uterine cavity by inserting a narrow tube-like telescopic camera (hysteroscope) into the uterus through the cervix. It is very useful for assessing submucous fibroids and the overlying endometrium. It is usually necessary for patients who claim to have abnormal vaginal bleeding and/or recurrent miscarriage.
Surgery is considered the standard treatment for women who suffering from fibroids. Two most common procedures to surgically remove fibroids are hysterectomy and myomectomy. An alternative to surgery is uterine artery embolization (UAE).
Hysterectomy is a procedure of removing the entire uterus including the cervix, which can be performed either laparoscopically or laparotomically. It is usually an option for women who have completed their family planning and are above 40 years old. The advantage of hysterectomy over myomectomy is that it eliminates the possibility of fibroid recurrence and puts an end to all the symptoms including heavy menstrual bleeding, which may persist even after a myomectomy is done.
Myomectomy is a procedure of removing the fibroids without removing the uterus. It can be performed either laparoscopically or laparotomically. The main advantage of myomectomy is that it preserves patients' ability to conceive. One disadvantage of it is that, it may cause considerably blood loss during surgery that blood transfusion is needed. Other disadvantages are possible recurrence and possible persistence of heavy menstrual bleeding after surgery. In cases of recurrence, subsequent myomectomy will be more complicated as the previous one may have led to formation of adhesions (scar tissue).
- Uterine artery embolization (UAE)
UAE is conducted under a moving X-ray (fluoroscopy) by an experienced interventional radiologist. It is a procedure where a tiny tube called catheter is inserted through an incision in the groin area into the femoral artery and then threaded to the uterine arteries. Some tiny sand-like gelatinous particles will be injected into the uterine arteries through the catheter in order to block the blood supply to the fibroids. The blockage or embolization will eventually result in degeneration of the fibroids. The advantages of UAE are minimal blood loss, fertility preserved and short recovery period. The disadvantages of it are that patient may experience post-embolization syndrome (PES) such as severe pelvic pain and cramping, nausea and vomiting that lasts for several days following the procedure; the embolization may cause damage to the uterus and uterine infection may arise. Also, when the fibroids start to degenerate, they can cause severe pain to the patient.