Fibroids are growths arising
from the muscle wall of the
uterus. It is a round and firm
structure amid the soft muscle
layer. When cut open, the pale
and dense cut surface gives us
the impression that it is a growth
of densely packed fibrous tissue.
The growth attracts the common
name of fibroid because of these
In medical term, fibroid is known as
leiomyoma. It reflects the true nature
that the growth is a benign (not
cancerous) tumour developed from
abnormal muscle cells of the uterus, not
Fibroids are the most common noncancerous
growths in women. They can
develop in women of any age after the
onset of menstruation. The incidence
increases with age. By 40 years old,
more than 50 percent of women
would have one or more fibroids. It
is not uncommon to see mother and
daughters or sisters in the same family
Fibroids are typically silent in at least 60 percent of women. They are discovered on a routine examination of the pelvis or when an ultrasound scan of the pelvis is carried out for some other reasons. In the other 40 percent of women, fibroids may cause one or more of the following symptoms:
On examination of the pelvis, a doctor may suspect a fibroid if the uterus is found to be larger in size than normal or the contour of the uterus is irregular.
The diagnosis is typically based on the finding of a growth on ultrasound scan of the uterus. CT-scan or magnetic resonance imaging (MRI) scan of the abdomen and pelvis will also show the presence of uterine fibroids.
A common condition, fibroids are found in many women who experience difficulty in becoming pregnant. There is, however, no evidence to show that fibroids cause infertility. If they do, it happens only in a very small proportion of women, for example, in a situation when a fibroid of moderate size located near the fallopian tube causes a blockade in the tube.
It is a common belief that fibroid can cause the pregnancy to miscarry. Research has not shown a conclusive evidence for this belief. Why miscarriage seems to happen commonly in women who have fibroids can be explained by the facts that both fibroids and miscarriage are commoner as a woman becomes older. In fact, the great majority of women with fibroids, including those with a large fibroid, continue the pregnancy with no abnormal outcomes.
A peculiar complication of fibroids during pregnancy is an uncommon change in the fibroid known as ‘red degeneration’. This condition causes abdominal pain that may require treatment with pain killers. This condition, however, has no adverse outcome on the pregnancy in terms of miscarriage or premature birth of the baby.
Each fibroid develops from a single muscle cell in which certain genes have been damaged or altered. The genetic changes lead to a more rapid cell division than usual in response to stimulation of hormones and growth factors. The cell division is also uncontrollable which results in a large number of abnormal muscle cells and the formation of a visible growth.
It is quite common for muscle cells from different parts of the uterus to develop these genetic changes over a period of time. This results in the forming of many fibroids on the same uterus.
The cause of genetic changes is currently unknown. It is clear that there is no fibroid gene that can be passed from mother to daughters in a direct genetic inheritance manner. There is also no association of fibroids with dietary habits or history of childbearing.
Although the muscle cells made up of fibroids are abnormal in their genes, they are responsive to oestrogen, the female sex hormone.
During the years that a woman is menstruating, oestrogen stimulation leads to the continual growth of fibroids. In general, a fibroid increases in size by 1 cm a year.
During pregnancy, fibroids are known to grow more rapidly than during the non-pregnant period.
At menopause as oestrogen secretion ceases, many fibroids shrink in size slowly in the post-menopausal years. However, fibroids will not disappear completely, even years after menopause.
Some other growth factors are known to influence the growth of fibroids. These growth factors are not changed by menopause. This explains why some fibroids fail to shrink or may even continue to grow despite menopause.
Fibroids can be classified according to their size (Table 1) or by their location in the uterus (Table 2):
Table 1: Classification of fibroids by size
Table 2: Classification by location
It is very common for fibroids of different sizes and locations to be present on the same uterus.
The majority of women have small
or moderate size fibroids. In general,
these women do not experience any
problem from the fibroids and do not
require treatment. In other women,
the decision on initiation and choice
of treatment of fibroids depends on
individual circumstances. The treatment
available includes the following:
Treatment of heavy menstrual flow
Menstrual flow can be reduced with
medication such as tranexamic acid,
danazol, progesterone hormone or
gonadotrophy releasing hormone
analogues. This form of treatment is
appropriate when the fibroid is small
or moderate in size. It is also more
appropriate among women who are
close to menopause when treatment
may be limited to a short period of
time before menopause ensues. This
treatment is not a cure of fibroids.
Hysteroscopic resection of fibroid
Submucus fibroid or fibroid polyp can
be effectively removed by resection
through a hysteroscope. It is a
minimally invasive procedure through
the vaginal and cervical approach. This
technique is suitable for women of
any age, including those considering
pregnancy in the future.
Uterine artery embolisation
Solitary fibroid of moderate or
moderately large size can be treated by
blocking the blood flow (embolisation)
to the fibroid. This is an interventional
radiology procedure involving inserting
an arterial catheter to the uterine artery
under fluoroscopic guidance. This
technique is not a complete cure for
Instead, after successful arterial
embolisation, the size of the fibroid
can shrink by almost 60 percent and the
heavy menstrual flow can be reduced
by almost 80 percent. The treatment
is appropriate for women who want
to avoid the risk of surgery. It is not
appropriate for women whose fibroids
need to be submitted for pathological
Surgical removal of fibroids,
also known as myomectomy
In this operation, fibroids are removed
and the uterus is repaired for
resumption of its normal menstrual
and childbearing functions. Fibroids
of moderate to moderately large sizes
can be effectively removed through
laparoscopic surgery. Laparoscopy is
proven to be efficient and is associated
with less pain and shorter recovery time
compared to conventional surgery.
Robotic surgery is an alternative
minimally invasive procedure for
treating these types of fibroids.
On the other hand, traditional open
surgery remains the most versatile
approach to remove all fibroids,
regardless of the size and their location
on the uterus. Good surgical repair
on the incisions on the uterus confers
additional safety on the integrity of the
wounds in ensuing pregnancies.
Hysterectomy or removal of the
For women who do not desire to
conserve the fertility potential, removal
of the uterus (hysterectomy) confers
the most appropriate and complete
Once the fibroids are removed, the
uterus resumes its normal structure.
There remains a potential risk that
some muscle cells may develop genetic
changes leading to development of
new fibroids. There is a 10-30 percent
chance that new fibroids will develop
after the myomectomy operation. There
is obviously no recurrence of fibroids if
a hysterectomy is performed.
Fibroids are by nature non-cancerous
tumours. The malignant form of fibroid
is known as leiomyosarcoma. It is a
very rare tumour developed from
abnormal muscle cells unrelated to
fibroids. It can occur in the uterus with
existing fibroids or without fibroids.
Development of malignancy within an
existing fibroid is extremely rare and
is not a consideration for decision for
surgery on fibroids.
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