The uterus is composed of a thick layer of smooth muscle (myometrium)
surrounding a thin lining (the endometrium) into which the embryo
implants and which serves to protect and nourish a growing pregnancy. It
is the thin endometrium which is shed each month during the
menstruation, if pregnancy does not occur. Some have stated that it is
as though the uterus “weeps tears of blood in mourning for the fact that
conception did not take place in the cycle. In other words, all
hormonal events of the menstrual cycle, have a single purpose in mind –
namely successful conception.
Approximately 20-40% of all reproductive age women will develop
benign growths of the myometrium, referred to as fibroid tumors
(leiomyomata). These tumors are rarely malignant (see below). They can
be located in the wall of the uterus (intramural), on the outside of the
uterus (subserosal), within the uterine cavity (submucosal), on a thin
stalk (pedunculated) or any combination of the above. They are hormone
dependent lesions and estrogen causes them to grow. African and African
American women seem to have a much higher incidence of fibroid tumors.
This is indicative of the fact that their cause has a fundamental
genetic basis.
Most fibroids start as very small lesions (sometimes referred to as
“seedling fibroids”) and they can grow to very large sized lesions.
Fibroids as big as watermelons have been reported in the literature. The
impact of fibroid tumors on successful reproduction, have a lot to do
with location (see below).
Presentation, Symptoms and Signs associated with Uterine Fibroids
Fibroid tumors, even large ones, can occur without producing any
symptoms at all (asymptomatic). However they can also cause a variety of
symptoms depending on their size, location and the absence or presence
of complications such as tortion (twisting) or degeneration (such as
might occur when a fibroid grows so fast that it starts running out of
its blood supply). The most common symptoms are heavy cyclical menstrual
bleeding (menorrhagia) accompanied by menstrual pain (dysmenorrhea).
Sometimes, especially when a fibroid protrudes into the uterine cavity,
it can cause erosion of the endometrial lining and produce irregular or
continuous bleeding (menomettrorhagia).Sustained non-menstrual pelvic
pain may point to tortion of a pedunculated fibroid that is attached to
the inner or outer wall of the uterus, or to degeneration, Other
possible symptoms include pain with deep penetration during intercourse
(deep dyspareunia), bladder irritability, rectal pressure, constipation
and painful bowel movements (dyschezia). If a fibroid undergoes
degeneration, it can become secondarily infected and in addition to
pain, the patient may have fever and chills.
Effect of Fibroids on Reproduction
For the most part, only those fibroids that impinge upon the
endometrial cavity (submucosal) affect fertility. Exceptions include
large intramural fibroids that block the openings of the fallopian tubes
into the uterus, and where multiple fibroids cause abnormal uterine
contraction patterns. Another lesion that can cause significant problems
is the one that grows off the back side of the uterus and occupies to a
greater or lesser degree, the cui de sac (area behind the uterus). This
location is very important in the physiology of conception, therefore
it is not uncommon to see patients with these kinds of lesions present
with infertility. Surgery to treat fibroids can also affect fertility in
several ways. If the endometrial cavity is entered during the surgery,
there is a possibility of post operative adhesion formation within the
uterine cavity. This should always be checked for through the
performance of a hysteroscopy or fluid ultrasound prior to beginning
fertility treatment. Because myomectomy can be bloody, there is a high
likelihood of abdominal adhesion formation, which could encase the
ovaries, preventing the release of the eggs or block the ends of the
fallopian tubes, or otherwise interfere with the normal functioning and
relationships of the pelvic organs. For this reason it is important that
only accomplished surgeons, who are familiar with techniques to limit
blood loss and prevent adhesion foundation, perform myomectomies.In some
cases multiple uterine fibroids may so deprive the endometrium of blood
flow, that the delivery of estrogen to the uterine lining (endometrium)
is curtailed to the point that it cannot thicken enough to support a
pregnancy. This can result in early 1st trimester (prior to the 13th
week of pregnancy) miscarriages. Large or multiple fibroids, by
curtailing the ability of the uterus to stretch in order to accommodate
the spatial needs of a rapidly growing pregnancy, may precipitate
recurrent 2nd trimester (beyond the 131h week) miscarriages and/or
trigger the onset of premature labor. As stated above, the location of
the lesions is very important in the symptoms/impact. A lesion
positioned just beneath the endometrial lining can make the structural
integrity of the endometrium quite unstable and the therefore, unable to
develop in a progressive manner in preparation for implantation of the
embryo.
Diagnosis
Sizable fibroid tumors are usually easily identified by simple
bi-manual vaginal examination. However, even the smallest fibroid can be
identified by transvaginal ultrasound. Sometimes it is difficult to
tell if a fibroid is impinging on the endometrial cavity. In such cases,
a hysteroscopy (where a telescope like instrument, is inserted via the
vagina into the uterine cavity) or a hysterosonogram (where injected
t1uid, distends the uterine cavity allowing for examination of its
contour and inner configuration) can help distinguish between intramural
and submucosal. Magnetic Resonance Imaging (MRI) can be used to
distinguish between fibroid tumors and a related condition called
adenomyosis, in which diffuse or localized foci of endometrial tissue
can be found within the myometrium. Given the often-diffuse nature of
adenomyosis, it is difficult to remove surgically. This contrasts with
fibroid tumors, which are well defined and are usually relatively easily
removed at surgery.