Fibroids are smooth muscle tumors of the uterus.
They grow from the muscle cells of the uterus and
are also called uterine leiomyomas, or myomas. They
are benign ( non-cancerous), and are the
commonest tumours found in a young woman. Since they
are so common ( about 25% of women in the
childbearing group will have fibroids) , many
infertile women will also be found to have fibroids.
However, most fibroids do not affect fertility and
can safely be left alone. Unfortunately, many
doctors are very anxious to surgically remove these,
and this unnecessary surgery can actually cause
infertility ! Fibroids are classified according to
their location and are of 3 types. The uterus has 3
layers - the inner lining which lines the cavity,
called the endometrium; the wall of the uterus which
consists of smooth muscle, called the myometrium;
and the outer lining , called the serosa. A fibroid
which grows in the muscular wall of the uterus is
called an intramural ( "within the wall" ) fibroid.
A fibroid which grows mainly on the outer surface of
the uterus, under the serosa, is called subserosal.
A fibroid which grows just under the uterine lining,
inside the uterine cavity, is called a submucous or
intracavitary fibroid.
Although the exact cause is unknown, the growth of
fibroids, like all tumours, seems to be
related to a gene that controls cell growth.
Fibroid growth is also affected by the reproductive
hormones estrogen and progesterone. The majority of fibroids are small and do not cause
any symptoms at all. Most fibroids in infertile women
are detected on a routine pelvic examination; or during
ultrasound scanning. However, submucous fibroids can
cause increased uterine bleeding; and very large
fibroids can cause pelvic pressure.
What about the relationship of fibroids and
infertility ? It's easy to understand how a submucous
fibroid which protrudes into the uterine cavity or
causes distortion of the uterine cavity may act as a
foreign body, and present a mechanical barrier to
implantation. However, most other fibroids do not affect
fertility. This is still controversial, because some
doctors believe that intramural fibroids may cause an
alteration or reduction of blood flow to the uterine
lining , making it more difficult for an implanted
embryo to grow and develop.
Most women with fibroids have completely normal
pregnancies and deliver healthy babies with no
complications. Women with large fibroids may have an
increased risk of some problems during pregnancy,
however, such as breech presentation of the fetus,
premature rupture of the “bag of waters”, and abruptio
placenta (a condition in which the placenta separates
from the uterine wall during the pregnancy).
Most fibroids are diagnosed during an ultrasound
examination. One limitation of ultrasound is the
inability in many cases to determine the relationship of
the fibroids to the uterine cavity . This is why
additional tests may need to be performed. These
include:
Hysterosonogram
This is an excellent test for determining the
relationship of fibroids to the uterine cavity.
During the ultrasound examination, saline is
instilled into the uterine cavity through a
catheter. This separates the walls of the uterine
cavity just enough to allow an ultrasound to detect
abnormalities inside the cavity.
Hysterosalpingogram
The hysterosalpingogram uses radiopaque dye to
visualise the uterine cavity; and can diagnose only
submucous fibroids, which appear as "filling
defects" or distort the cavity.
Hysteroscopy
In an infertile woman this is a key diagnostic tool,
because it allows us to detect fibroids that are
within the uterine cavity or cause significant
distortion of the cavity.
MRI
Magnetic resonance imaging is an expensive way of
defining the location and size of fibroids, and is
rarely used.
Most fibroids in infertile women do not need any
treatment at all, because they do not affect fertility
or pregnancy. They are best left alone ! In fact,
unnecessary surgery can actually reduce your fertility,
because it causes adhesions and scarring which can
damage the tubes.
However, submucous fibroids in infertile women (
those within the uterine cavity or causing significant
distortion of the cavity ) do need to be removed; and
these are best removed by doing an operative
hysteroscopy. This requires a skilled surgeon, who
should document the surgery on video or CD.
The standard operation for removing fibroids is
called a myomectomy. This was traditionally done through
open surgery; and can also be performed
laparoscopically. However, this is of very limited use
in infertile women, because this surgery removes only
subserosal and intramural fibroids, most of which can be
left alone in infertile women.
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