The endometrium is the inner lining of the uterus that
is shed each month at menstruation. When the cells that have
the same appearance under the microscope as the endometrium
are found outside the uterus, the condition is known as endometriosis.
Just as endometrium is under hormonal control, so is endometriosis.
It progresses through the typical cycle changes of the endometrium
under the influence of estrogen and progesterone.
It is difficult to know the true incidence of endometriosis
in the general population. It is commonly stated that approximately
30% of infertile women will have endometriosis to some degree.
In the general population, estimates of 5-10% have been reported.
There have been thousands of scientific publications
about endometriosis, yet the disease remains poorly explained.
There seem to be numerous factors that collectively alter
an individual’s predisposition to develop endometriosis.
While endometriosis is not directly inherited, it is more
common in some families. A specific endocrine, immunologic
or even lifestyle may be a predisposition.
There are two well-entrenched theories
about how an individual develops endometriosis. The first
and longest standing theory is that of retrograde menstruation.
According to this theory, endometriosis comes as a result
of a back flow of blood from the uterus through the tubes
and out into the pelvis. The problem with this theory is that
most, if not all, women have some degree of menstrual fluid
back flow. Maybe it’s an issue of quantity, but then
maybe there is an additional factor.
A second theory of origin of endometriosis
is that the cells lining the pelvis and ovaries are transformed
into endometrial cells by some internal or external stimulus.
Perhaps blood and all the growth factors it contains are good
candidates for being this stimulus. This makes good theoretical
sense. The lining of the pelvic cavity, including the surface
of the ovary, has the same embryologic origin as the endometrium.
Whether by genetic predisposition, alteration of immunology,
stimulation by hormones, or chronic irritation from menstrual
reflux, the peritoneal cells are transformed into endometrium.
These theories are not mutually exclusive
and it is quite possible that they act in concert in the development
of endometriosis. An experiment supporting this combination
of two theories has been carried out in nature in women with
a congenital anomaly that naturally blocks the normal blood
flow through the cervix at menstruation. Endometriosis is
a very common finding in these individuals. Several studies
have linked the diameter of the cervix with the propensity
to develop endometriosis. The tighter cervix, the smaller
the cervical diameter, the greater the chance of menstrual
back flow and the development of endometriosis. It is possible
that endometriosis is slightly more common in individuals
with a retroverted or tipped uterus.
The most common sites of endometriosis
formation are the areas that are most easily bathed in menstrual
blood. These common sites include the ovaries, with their
close approximation to the tube in order for egg pick up at
ovulation. Other sites are the uterine sacral ligaments that
stretch from the cervix to the sacrum in shelf-like folds
of peritoneum. These are very common sites of menstrual fluid
accumulation. Adjacent to the uterine sacral ligaments are
a rich supply of nerves supplying the cervix and uterus. Endometriotic
implants along these ligaments are commonly associated with
painful intercourse and dyspareunia. Occasionally, nodules
can be felt by pelvic examination, or in severe cases, the
uterus may be felt to be fixed and not movable. The third
most common site is along the anterior folds of peritoneum
above the bladder. Endometriosis along the surface of the
intestine is relatively common and can explain the high association
with altered bowel function. Endometriosis of the appendix
sometimes occurs.
In the past, endometriosis was thought to be most commonly
seen in the thin, “type A,” professional woman
who had regular menses and postponed childbearing. This is
obviously not the case, and we now recognize that endometriosis
transcends all ages and races. While less common, severe endometriosis
is occasionally found in teenagers. Even in this young group,
pain should not be dismissed or attributed to “just
a normal part of growing up.” There should especially
be concern about the possibility of co-existence of endometriosis
in all infertility patients, especially, when it seems that
ovulation induction therapy is working but a pregnancy is
still not forthcoming.
- Short time between periods (less than 26 days)
- Long periods (over 5 days)
- Heavy bleeding
- Congenital uterine abnormalities
- Cervical stenosis
- Postponed childbearing
- Lack of oral contraceptive use
- Infertility
- Pain
The chance of endometriosis increases
as the number of these factors increases. The two central
risk factors for endometriosis include pain and infertility.
Endometriosis is not inherited as such, but it is more
common in some families. It is best to consider that the propensity
for endometriosis is inherited rather than that the disease
itself. The development of endometriosis can be related to
certain modifiers, such as the tendency not to ovulate, to
have heavier periods, to have the uterus tilted such that
back-flow of blood is more likely or an immunologic incompetence,
each of which itself may be inherited. Clearly, however, inheritance
of endometriosis is not direct and predictable. One family
member who decides to postpone childbearing may develop endometriosis,
while a second with the same genetic tendencies and two children
may remain endometriosis-free.
Abnormal pain associated with
menstruation or ovulation is endometriosis until proven otherwise.
The triad of painful menstruation (dysmenorrhea,)
painful intercourse (dyspareunia) and painful bowel
movements (dyskezia) are the most common reported
pain abnormalities. Often, patients have been misdiagnosed
with irritable bowel syndrome when diarrhea and constipation,
along with intestinal pain, are related to menses. Certainly
if there is a bleeding sore on the rectum, the bowel would
be irritable. During intercourse, the upper portion of the
vagina is adjacent to the most likely areas of endometrial
involvement. The relationship between PCOS and other bowel
disturbances such as Crohn’s disease and ulcerative
colitis has not been reported. These diseases would seem to
have a hormonal relationship in that they can be made better
and worse by pregnancy.
Pelvic pain is much more likely
in the times of marked hormonal change, such as ovulation
and menstruation. Individuals with endometriosis are known
to produce much more prostaglandin and that is clearly related
to the amount of pain. Anti-inflammatory agents such as ibuprofen,
naprosyn, and aspirin are effective in relief of menstrual
pain in some individuals.
While ultrasound scan cannot detect
the scarring or implants of endometriosis, it may yield a
high suspicion for the disease by highlighting the characteristic
cystic changes of the ovary. Endometriosis, which is a surface
lesion, incorporates into the ovary and eventually forms a
walled-off cyst, an endometrioma. It is possible
that endometriomas are more likely to form from a raw area
of the ovary at the time of ovulation and the formation of
the corpus luteum. An endometrioma is a particularly ominous
finding that will almost always indicate some degree of ovarian
compromise. It is often called a chocolate cyst because
of the enclosed endometrial fluid, which is a combination
of old blood and endometriotic tissue, has the consistency
of chocolate syrup.
While history and pelvic exam
may suspect the diagnosis of endometriosis, direct viewing
at surgery can only make the definitive diagnosis.
Endometriosis can be thought of as having two different
components. There is an active component that represents the
cyclic changes seen with waxing and waning of the endometrium.
This form may be amenable to either medical or surgical therapy.
The second portion of endometriosis, a fixed variety, is represented
by the residual scarring from the endometriosis and is only
corrected by surgery.
Since endometriosis is a surgical diagnosis, and
surgery is invasive and thus always carries an inherent risk,
virtually all physicians recommend that endometriosis be treated
at the time it is found rather than be treated in a second,
subsequent operation. Endometriosis has been classified due
to the findings at surgery as either minimal (stage 1,) mild
(stage 2,) moderate (stage 3,) or severe (stage 4.) There
is little correlation between the stage of endometriosis and
the amount of pain. However, the more severe the endometriosis,
the more likely it is that the patient will be infertile.
Minimal and mild endometriosis is associated with infertility,
but it is unclear if the early stages “cause endometriosis.”
Endometriosis may have a variety of
presentations at surgery. They correspond to the progression
of the disease from inflammation of the peritoneum to dense
scarring as the lesion heals. Endometriosis may be seen as
clear blobs or reddened blister-like lesions with abnormalities
of the associated small blood vessels. In the past, many lesions
thought to be the earlier stages of endometriosis were overlooked.
The typical lesion of endometriosis has been described as
a “powder burn” lesion connoting that there has
been bleeding at the site of the endometriosis and deposition
of black pigment as the area of bleeding heals.
The small areas of endometriosis can
be compared to a small open sore that is constantly being
irritated. There is associated inflammation and finally a
slow healing process by scar formation. The end results of
endometriosis are dense whitened areas of scarring and adhesions
(abnormal attachments.) Sometimes, adhesions produce no symptoms
while in other cases there can be severe pain. Adhesions can
limit the mobility of the pelvic organs and cause infertility.
Surgical techniques fall into
two categories—excision and destruction. Many experts
believe that an excision is preferable, but this may be more
difficult around the vital organs and large areas of dissection
may increase the amount of post surgical adhesion formation.
Certainly, all areas of endometriosis should be treated and
this may involve surgery around vital structures such as the
ureters, bladder, major blood vessels, and intestines. A variety
of techniques including a laser, electro-cautery, and a new
device called a harmonic scalpel, which uses ultrasound waves
to destroy tissue, may be used. The latter differs slightly
in its method, but none have been shown to be more superior
to the others. Treatment probably relies on the skill of the
surgeon rather than the equipment.
There are a variety of medical treatments for endometriosis.
Two gold standard treatments are Danazol (Danocrine) and GnRH
analogs. Danazol is an androgen-like drug shown to suppress
ovulation and cause the regression of endometriosis. Its side
effects include weight gain in virtually all users. Occasional
side effects of the androgen include acne, abnormal hair growth,
and mood changes.
The primary medical therapy for endometriosis
are the gonadotropin releasing hormone (GnRH) analogs that
shut down the stimulation of the ovary and in doing so, create
a reversible menopause. The side effects of the GnRH analogs
relate to induction of a menopausal state with vasomotor instability,
vaginal dryness, insomnia, and bone loss. GnRH analogs may
potentially improve PCOS and is probably the treatment of
choice. (See Chapter 16.) Usually the GnRH analogs are limited
to a six-month treatment. In an attempt to reduce side effects
and to prolong therapy, “add back” regimens involving
giving low doses of hormonal replacement in addition to the
GnRH analogs are used. It is unsure how long this therapy
could be maintained, but it should have a positive effect
on PCOS and has been recommended as an expensive therapy.
Other medical therapies include
continuous use of oral contraceptives. Using the pill in the
usual cyclic fashion with “dummy” and regular
withdrawal bleeding may retard the development of endometriosis,
but it is often not sufficient to treat the disease. Progestins
such as Depo-Provera have also been used, but the effectiveness
is less reliable. Unfortunately, all medical therapy is probably
temporary and endometriosis may continue to progress.
There is no cure for endometriosis.
The objectives remain to move from infertility to a successful
pregnancy and from intolerable pain to tolerable discomfort.
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