|
Uterine fibroids are nodules of smooth muscle
cells and fibrous connective tissue that develop within the wall of the
uterus (womb). Medically they are called uterine leiomyomata (singular:
leiomyoma). Fibroids may grow as a single nodule or in clusters and may
range in size from 1 mm to more than 20 cm (8 inches) in diameter. They
may grow within the wall of the uterus or they may project into the
interior cavity or toward the outer surface of the uterus. In rare
cases, they may grow on stalks or peduncles projecting from the surface
of the uterus.
The factors that initiate fibroid growth are not
known. The vast majority of fibroids occur in women of reproductive age,
and according to some estimates, they are diagnosed in black women two
to three times more frequently than in white women. They are seldom seen
in young women who have not begun menarche (menstruation) and they
usually stabilize or regress in women who have passed menopause.
Fibroids are the most frequently diagnosed tumor of
the female pelvis. It is important to know that these are benign tumors.
They are not associated with cancer, they virtually never develop into
cancer, and they do not increase a woman's risk for uterine cancer.
No one knows how many new cases of uterine fibroids
occur within any given length of time nor how many women have fibroids
at any time. It has been estimated that up to 20 to 30 percent of women
of reproductive age have fibroids, though not all have been diagnosed.
More careful studies, however, indicate that the prevalence may be much
higher. A study of 100 uteri that had been removed in consecutive
hysterectomies yielded the following results: 33 had been diagnosed as
having fibroids prior to surgery; routine pathologic examination
disclosed that 52 had fibroids. However, a surprising 77 specimens were
found with fibroids upon very close examination. The majority of the
tumors were less than 1 cm in diameter and were missed during routine
pathologic examination. These results indicate that more than
three-quarters of women have uterine fibroids.
This is a small study, however, and its results should
not be interpreted as applying to the entire female population, but as
an indicator that perhaps the prevalence of fibroids is much higher than
has been believed.*
Who
is at Risk for Uterine Fibroids?
No risk factors have been found for uterine fibroids
other than being a female of reproductive age. However, some factors
have been described that seem to be protective. In some studies, again
of small numbers of women, investigators found that as a group, women
who have had two liveborn children have one-half the risk of having
uterine fibroids compared to women who have had no liveborn children. It
could not be discerned whether having children actually protects a woman
from developing fibroids or whether fibroids contributed to the
infertility of women who had no children.
Obese women in some studies were at increased risk of
having fibroids, but other studies failed to confirm this. A lower risk
has been found in both smokers and users of oral contraceptives in some
studies, but not in all. However, it is important to note that smoking
poses far greater health hazards than do uterine fibroids. Athletic
women also seem to have a lower prevalence compared with women who do
not engage in any athletic activities.
In view of the lack of information on fibroids,
the National Institute of Child Health and Human Development (NICHD) is
conducting research on the scientific bases for better diagnosis and
treatment of fibroid tumors. It is hoped that the results of this
research will enable the medical community to better predict who is at
risk for fibroids, what can be done to prevent their development, and/or
how to provide the most effective treatment for them.
Symptoms
of Uterine Fibroids
How do you know if you have uterine fibroids?
Probably you do not know. Most fibroids do not cause any symptoms and do
not require treatment other than regular observation by a physician.
Fibroids may be discovered during routine gynecologic examination or
during prenatal care. Some women who have uterine fibroids may
experience symptoms such as excessive or painful bleeding during
menstruation, bleeding between periods, a feeling of fullness in the
lower abdomen, frequent urination resulting from a fibroid that
compresses the bladder, pain during sexual intercourse, or low back
pain. Although reproductive symptoms such as infertility, recurrent
spontaneous abortion, and early onset of labor during pregnancy have
been attributed to fibroids to any of these symptoms. In rare cases, a
fibroid can compress and block the fallopian tube, preventing
fertilization and migration of the ovum (egg); after surgical removal of
the fibroid, fertility is generally restored.
Treatment
for Fibroids
Until very recently, a woman with growing
uterine fibroids was considered a candidate for hysterectomy (removal of
the uterus). However, treatment by hysterectomy in a woman of
reproductive age means that she will no longer be able to bear children
and hysterectomy may have other effects, both physical and
psychological, as well. A woman considering hysterectomy should discuss
the pros and cons thoroughly with her physicians.
Although the number of hysterectomies has been
declining since 1987, this operation remains the second most frequently
performed surgery in the U.S.; only cesarean section is performed more
frequently. Fibroids remain the number-one reason for hysterectomy with
150,000 to 175,000 operations carried out each year because of fibroids.
Hysterectomy for uterine fibroids historically has
been based on uterine size. Once the uterus reached the size that it
would be in the 12th week of pregnancy it was considered time to perform
a hysterectomy. The decision was based mainly on the fact that fibroids
of such volume could shield the presence of uterine cancer. Without
effective diagnostic procedures the medical community considered it
safer to remove the uterus than to possibly harbor a growing malignancy.
Now, however, improved imaging procedures such as ultrasound and
magnetic resonance imaging (MRI) can effectively determine whether or
not a rapidly growing tumor is present, reducing the number of
hysterectomies performed. Therapy for uterine fibroids should be based
on symptoms and not the idea that uterine fibroids will continue to grow
until it becomes necessary to perform a hysterectomy.
If a fibroid is particularly troublesome, the surgeon
often can remove only the tumor. leaving the uterus intact (leiomyomectomy).
This may leave the wall of the uterus weakened, in
which case any pregnancy that occurs later most likely will be delivered
by caesarean section. Many women with fibroids have successful outcomes
of pregnancy with no undue incidence of miscarriage or other unfavorable
outcome.
More and more, physicians are beginning to realize
that uterine fibroids may not require any intervention or, at most,
limited treatment. For a woman with uterine fibroids that are not
symptomatic the best therapy may be watchful waiting. Some women never
exhibit any symptoms or have any problems associated with fibroids, in
which case no treatment is necessary. For women who experience
occasional pelvic pain or discomfort, a mild, over-the counter
anti-inflammatory or painkilling drug often will be effective. More
bothersome cases may require stronger drugs available by prescription.
The fact that fibroids seemingly are
estrogen-dependent has led to attempts to control them by reduction in
available estrogen. Hormone-like agents that counter the action of
gonadotropin-releasing hormone (GnRH) are being investigated as one such
agent. The use of a GnRH agonist lowers blood levels of estrogen and
reduces uterine volume by as much as 60 percent.
Of primary concern in the use of such agents is the
possibility of increasing blood cholesterol levels and reducing bone
density, which may lead to osteoporosis. Although only modest increases
in blood cholesterol have been noted in women undergoing this treatment,
the therapy itself was of short duration. Unfortunately, the uterus
returned to its pre-treatment size within 3 to 6 months after GnRH
agonists were stopped.
It would seem from these observations that the use of
GnRH agonists is of limited application. But, in fact, defined protocols
have been worked out for administration of these agents for use in women
who have symptoms, are poor candidates for surgery, and are nearing
menopause. Also, for patients needing a hysterectomy, the use of GnRH
agonists can reduce uterine size considerably, making abdominal
hysterectomy easier or even allowing a vaginal hysterectomy rather than
an abdominal one.
Three GnRH agonists are currently available. Two must
be given by injection and the third is administered by an inhaler. Side
effects that have been found include hot flushes, depression, insomnia,
decreased libido, and joint pain. Maximum uterine shrinkage is achieved
after 3 months of therapy.
Studies have only just begun on the newest class of
antihormonal agents, the antiprogestins, the best known of which is RU
486.* Even though fibroids appear primarily stimulated by estrogens,
drugs in this class which oppose the other major female hormone,
progesterone, also seem to be effective for treatment of uterine
fibroids. Studies using these drugs are still in the early stages.**
*Cramer, DW. Epidemiology of Myomas. Seminars in
Reproductive Endocrinology 10:320-324, 1992
* *Supported by San Diego Reproductive Medicine
Educational and Research Foundation, and NIH Grant RR-00827
***Murphy, AA et al. Journal of Clinical Endocrinology
and Metabolism
Vitamins and Minerals
Because many people with UC have vitamin and mineral deficiencies
(due to decreased nutritional intake and absorption by the colon and
excessive diarrhea), a multivitamin is recommended. Further research is
needed to determine whether specific vitamin or mineral supplements may
help treat the symptoms of UC.
Omega-3 Fatty Acids
At least one study has found that, compared to placebo, fish oil
supplements containing omega-3 fatty acids may reduce symptoms of UC and
prevent recurrence of the condition. The supplements are less effective
than sulfasalazine, however, at reducing inflammation in people with
mild to moderate UC. Some experts suggest that omega-3 fatty acids may
prove particularly valuable when used in combination with sulfasalazine
or other medications.
Vitamin
B9 (Folate)
People with UC often have low levels of folate in their blood cells
and some experts suggest that this may be due, at least in part, to
sulfasalazine use. Some researchers speculate that folate deficiencies
contribute to the risk of colon cancer in those with UC. Although
preliminary studies suggest that folate supplements may help reduce
tumor growths in people with UC, further research is needed to determine
the precise role of folate supplementation in people with inflammatory
bowel diseases.
N-acetyl glucosamine
Preliminary evidence suggests that N-acetyl glucosamine supplements
or enemas may improve symptoms of UC in children with IBD who did not
improve after using other treatments, but further research is needed to
determine whether the substance is safe and effective for the treatment
of UC. |