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UTERINE FIBROIDS-a patient's guide
Editorial Team
What are uterine fibroids?
Uterine fibroids are benign tumours formed from the muscular
layer in the uterus. Also known as uterine leiomyomas or
myomas, fibroids are the most common solid pelvic tumours
in women. As benign tumours, fibroids are not cancerous
(i.e. they do not spread beyond the uterus) and only extremely
rarely develop into malignant tumours (cancer).
Fibroids are classified according to where in the uterus
they form: either in the wall of the uterus itself (intramural),
beneath the inner lining of the uterus (submucosal) or beneath
the outer covering of the uterus (subserosal). In fact,
most fibroids are a combination of these types.
Who gets fibroids?
Fibroids are found in about 25% of women of reproductive
age during pelvic examinations, but probably occur in even
more: careful examination of surgical uterine specimens
demonstrates that over 80% have fibroids. However, symptoms
occur in only 20-50% of those with fibroids, usually in
women in their 30s or 40s. There are increasing reports
of women continuing to have, or developing symptoms, whilst
taking hormone replacement therapy in menopause.
What causes fibroids?
The exact cause of fibroids is not well understood, although
various factors have been recognised as being important
in their development. The hormones estrogen and progesterone
have a role in the formation of fibroids. Growth factors
and gene mutations are also involved in fibroid development.
The latter explains the hereditary predisposition for fibroids
seen in families.
(Although the levels of estrogen and progesterone are
high in both the oral contraceptive and during pregnancy,
they remain protective against the risk of developing fibroids.
This is perhaps because there is no fluctuation in the high
hormone levels during oral contraceptive use or pregnancy,
whereas hormone levels fluctuate widely during the normal
menstrual cycle.)
What are the symptoms of fibroids?
Many women have no symptoms from their fibroids at all.
However, fibroids may produce three main types of symptoms
in 20-50% of cases: abnormal menstrual bleeding, pressure
and pain, and reproductive problems.
The abnormal bleeding associated with fibroids usually
occurs during the normal time in the menstrual cycle, but
it is prolonged ('menorrhagia') and/or the flow is heavier
than normal ('hypermennorhoea'). Bleeding at other times
(i.e. not during a period) is NOT characteristic of fibroids
and should always be thoroughly investigated. Prolonged
or heavy menstrual bleeding may cause iron-deficiency anaemia.
It is also often socially embarrassing and can interfere
with work, because of the need to change sanitary protection
frequently.
Fibroids can cause pelvic pressure symptoms either because
they increase the size of the uterus, or because they press
on nearby organs. Fibroids as big as a 20-week pregnancy
are not uncommon. Those arising in the anterior (front)
part of the uterus may put pressure on the bladder - causing
urinary frequency - whilst those in the posterior (back)
part of the uterus may cause constipation, due to pressure
on the large bowel. Pain may occur if the fibroid degenerates,
or if it arises on a stalk from the uterus and then twists
on that stalk ('torsion').
Reproductive problems may occur, especially if the fibroid
distorts the cavity of the uterus. These include recurrent
miscarriage, infertility, premature labour, or complications
of labour (such as abnormal presentation of the fetus).
Many of these problems are directly related to the size
of the fibroid. If the placenta develops over a fibroid,
there is an increased risk of the placenta 'breaking away'
(placental abruption').
How are fibroids diagnosed?
Fibroids can be suspected if the uterus feels enlarged,
irregular and mobile during a pelvic examination. The diagnosis
is usually confirmed by ultrasound examination of the pelvis.
Magnetic resonance imaging (MRI) gives a clearer image of
the uterus, but the additional cost does not usually justify
its use in diagnosing fibroids. Other studies that are used
to help diagnose fibroids include hysteroscopy (insertion
of a thin telescope into the uterus via the vagina and cervix)
and hysterosalpingography (dye-study x-rays of the uterus
and fallopian tubes).
How are fibroids treated?
Because fibroids are not malignant, they do not require
treatment unless they cause symptoms. The main method of
treating fibroids is to surgically remove them. Hysterectomy
(removal of the uterus) is the most common technique used,
and may be the best option in women who have completed their
childbearing.
For women who wish to have more children, myomectomy may
be performed. This involves removal of the fibroid itself,
with preservation of the uterus. Myomectomy can be performed
via an abdominal incision, using a laparoscope, or via the
vagina/cervix, depending on the size and location of the
fibroid. There is a slight risk of uterine rupture during
subsequent pregnancies after laparoscopic myomectomy. It
is important to note that 25-51% of fibroids recur after
myomectomy, and that 11-26% of patients need a further operation.
Newer surgical treatments include endometrial ablation
(in which the lining of the uterus is removed) and uterine-artery
embolization (in which the uterine artery is blocked). Both
are used to control excessive menstrual bleeding, but the
former is reserved for those who have completed childbearing.
GnRH agonists are the most common medical (i.e. nonsurgical)
therapy available for the treatment of fibroids. They induce
a state of low estrogen levels, (hormonally similar to the
menopause) which in turn reduces the size of the fibroids
and decreases the volume of the uterus. Most women also
stop having periods while taking GnRH agonists. This allows
those with iron-deficiency anaemia secondary to heavy/prolonged
menstrual bleeding to significantly increase their iron
stores and correct their anaemia. However, prolonged usage
of GnRH agonists may cause bone loss/osteoporosis and other
symptoms of the low estrogen state. Unfortunately, once
these drugs are stopped, the uterine size again increases
and menses resumes. Consequently, they are most useful in
reversing anaemia and decreasing uterine size in the short
term, thus preparing a woman for surgery.
Other medical therapies include androgenic (male hormone-like)
drugs and progesterone-type agents. However, these do not
consistently decrease the size of the fibroids or uterus,
and they often don't successfully control abnormal menstrual
bleeding. There is also ongoing research into combinations
of drugs that may be beneficial without the adverse effects
associated with using GnRH agonists alone.
Bibliography:
Feldman S, Stewart EA. The Uterine Corpus. In: Ryan KJ,
Berkowitz RS, Barbieri RL, Duanif A, eds. Kistner's Gynecology
& Women's Health:, 7th ed. St Louis: Mosby Inc, 1999: 121-42
Stewart EA. Uterine fibroids. Lancet 2001;357(9252):293-8
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