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Uterine Fibroid Embolization: Is it Universally Suitable?
J. Spies
Associate Professor of Interventional Radiology, Georgetown University School of
Medicine, Washington, DC, U.S.A.
Introduction
The growing acceptance of uterine artery embolization (UAE) as a treatment for
leiomyomata has led to its use in many centers across the country and the world. It has
created considerable interest among women and the lay press. Gynecologists are
becoming aware of the procedure and, in many centers, are regularly referring patients
for evaluation and treatment.
With several years of experience with this treatment around the world, sufficient data is
now available to allow some perspective of the outcome from this procedure. In this brief
overview, we will touch on the success of uterine embolization and then discuss the
failures: why they occur and how they may be avoided. We will conclude with a detailed
discussion of the criteria that are used in patient selection.
Symptomatic Outcome
Since 1998, 10 case series of 49 patients or larger have been published (excluding
duplicate reports) (1-10). These published results indicate that embolization is effective in
improving symptoms in the large majority of patients. Between 81 and 94% of patients
have improvement in their menorrhagia. For the bulk-related symptoms caused by
fibroids, which include pelvic pain, pressure and bloating, as well as urinary frequency,
symptoms are improved in 64-96% of patients. The variability in outcome relates in part
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to the means of assessment of outcome. In most of these series, the symptom follow-up
was obtained via questionnaire, with patients rating their symptom change.
Conversely, about 10 to 15% of patients are not improved after uterine embolization. A
systematic analysis of failure has never been published to our knowledge. However, one
can theorize the reasons that patients may fail to have symptomatic improvement. First,
misdiagnosis of the cause of a patient’s symptoms may occur. Once fibroids are
diagnosed, there is an assumption that all symptoms are related to the fibroids. Careful
evaluation before any fibroid intervention should reduce this occurrence.
From a technical perspective, the procedure may fail for 3 reasons. First, there may be
failure of catheterization and thus non-embolization of one side of the uterus. There may
also be reperfusion of the fibroids after apparently successful embolization of the blood
supply. This may result from redistribution of the particles after final embolization
images are obtained. Finally, parasitization of vascular supply from other sources may
result in failure. The most common source is the ovarian artery, which may supply the
fibroids in up to 5% of cases. For any of these reasons the fibroids may fail to infarct and
thus the symptoms may not improve.
Complications are very infrequent after uterine embolization. In a recent scientific
abstract detailing adverse events in 400 patients, complications occurred in 10%, the
large majority of which were minor, requiring treatment with medications only (11).
There was only 1 hysterectomy required for an adverse event, in this case bleeding
associated with fibroid expulsion 4 months after treatment. There have been
hysterectomies that have been required in less than 1% of patients (4, 10, 12) and 2
reported deaths, one from sepsis (13) and one from pulmonary embolus (14). Perhaps the
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most common complication requiring gynecologic intervention is fibroid expulsion that
occurs in 2.5 to 5% of patients (11, 15). This is one complication that may occur weeks or
months after the procedure.
Patient Selection
As with all medical therapies, the effectiveness and safety of uterine embolization
will be enhanced by the proper assessment and selection of patients prior to therapy. Not
only does the diagnosis of fibroids need to be confirmed, but also the symptoms that the
patient is having should correspond to the size and position of the fibroids. In addition,
other likely causes of symptoms and even important asymptomatic pathology should be
excluded. These efforts are greatly facilitated by a routine protocol for pre-procedure
assessment. This presentation is intended to provide the basis for developing a preprocedure evaluation protocol for fibroid patients.
Pre-Procedure Gynecologic Evaluation
Every patient should be evaluated by a gynecologist prior to UAE, preferably within
three months prior to therapy. This is not just to confirm the diagnosis of fibroids and to
confirm that the symptoms the patient is experiencing are due to fibroids. A patient’s
overall gynecologic health must be confirmed, including insuring that a Pap smear is
negative. In those cases when atypical symptoms are present or the pattern of bleeding is
unusual, additional gynecologic evaluation may be needed.
For all these reasons, a cooperative relationship with gynecologists is important. For
appropriate selection of patients for UAE and other fibroid therapies, it is important that
both specialties contribute their skills. As most interventionalists will realize, some
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patients are best treated by medical or surgical therapies and the relationship with
gynecologists will be reciprocal.
Pre-procedure Imaging
It is important to confirm the diagnosis of fibroids with pre-procedure imaging,
but also to assess the size and location of the fibroids. In particular, it is important to
correlate the fibroid’s position with the symptoms that the patient is experiencing. The
standard method of pre-procedure imaging is ultrasound, but we have routinely used MRI
instead.
We chose to use MRI for several reasons. First, it gives much superior anatomic
detail of the location and size of the fibroids when compared to ultrasound. The
measurements obtained are not as operator dependent as those obtained with ultrasound.
Ultrasound often has difficulty penetrating through very large uteri and often the ovaries
cannot be identified. In nearly all cases, we have been able to visualize the ovaries with
MRI. The internal architecture of the fibroids is much more readily apparent with MRI
and in particular it is possible to determine if a fibroid has already degenerated prior to
treatment. With the use of contrast, the enhancement pattern of the fibroids and the
surrounding uterus can easily be evaluated. If we determine that a fibroid is avascular
before treatment, we will be concerned that embolization will not help. Contrast use is
particularly important on follow-up scans. On occasion, we will note that a patient’s
fibroid may have only decreased in volume 10 or 20% three months post treatment. With
MRI, one can readily determine if the fibroid has successfully infarcted or whether there
is persistent viable tissue. This has helped us sort out those that were successfully treated
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from those that have failed as a result of aberrant or parasitized blood supply or
inadequate embolization.
Another key reason for using MRI is it is more accurate in diagnosing
adenomyosis. We have discovered several patients that had pure adenomyosis that had
had previous ultrasound diagnoses of fibroids. At this time it is not known if
adenomyosis can be treated with embolization with the same result as fibroids and
therefore we believe accurate diagnosis is important.
MRI protocol includes breathhold orthogonal single shot fast spin echo (Haste)
and T1 weighted spoiled gradient echo sequences obtained at 30 seconds, 60 second, and
90 seconds after the dynamic infusion of intravenous gadolinium.
We believe follow-up imaging after embolization should be obtained at least once
in each patient. This is important to ensure that the fibroid is infarcted and that it is
shrinking. If there is continued growth of the fibroid, it may mean that the “fibroid” was
in fact a leiomyosarcoma, which will obviously require surgery.
Patient Selection
Who to treat and who not to treat
After the work-up is completed, the decision remains: Should this patient be offered UAE
or should she have a different therapy?
The first decision is whether the patient’s symptoms warrant therapy. Presuming that the
symptoms are due to fibroids, are they severe enough to affect the daily life and activities
of the patient? Many patients will present with a diagnosis of fibroids and a
recommendation by a gynecologist to have a hysterectomy. This recommendation may be
given even in the absence of symptoms. The patient may then seek an alternative therapy,
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such as UAE. Many of these patients may only need reassurance that no therapy is
necessary, or at least not currently. The only circumstances when therapy is needed in
asymptomatic patients are those with hydronephrosis, a uterine mass that appears to
represent a sarcoma, and in patients with fertility problems that are directly referable to
the fibroids. In this last group, myomectomy is currently the procedure of choice.
The same logic can be used when the symptoms are mild. For heavy bleeding that is only
mildly increased over normal, medical therapy can be recommended when the bleeding is
not severe. These therapies include NSAIDS, birth control pills, and progesterone agents.
Bulk-related therapies do not respond well to medical therapies and generally UAE or
surgery are the only practical therapies. However, the patient should be reassured that
treatment can wait for the symptoms to become more severe before treatment is
undertaken. It should be remembered that our results are measured in symptom
improvement, and minimal symptoms will result in minimal benefit.
Given sufficient symptoms to treat, most patients are candidates for UAE. The patients
that might be better served by other therapies include those with pedunculated
submucosal fibroids, pedunculated dominant serosal fibroids, and massively enlarged
uteri.
Pedunculated submucosal fibroids may be amenable to hysteroscopic resection.
This is a simple outpatient procedure with excellent results in experienced hands.
However, the procedure usually requires pre-treatment with Lupron for three months to
devascularize the fibroid and reduce its size. Also, large (>4cm) fibroids may not be
easily resectable. However, we refer all patients with significant intra-cavitary fibroids
for a gynecologic second opinion. UAE certainly works in this group of fibroids and we
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have treated many patients in this group. However, these are in circumstances in which
hysteroscopic resection has failed or in which the patient has refused.
Large pedunculated subserosal fibroids that are the dominant or sole fibroid are
usually referred for myomectomy. UAE may work, but there have been concerns that
these may have parasitized blood supply from other pelvic vessels. There has also been at
least one case in France and perhaps others in which a pedunculated subserosal fibroid
sloughed into the abdominal cavity and became infected or caused significant intra-pelvic
adhesions. These fibroids are also easily accessible by surgery and until more data on the
behavior of this group of fibroids after UAE, myomectomy may be preferred.
Finally, we usually recommend that patients with a massively enlarged uterus
(greater than 22 to 24 cm in length) have a hysterectomy. This is based on our experience
that very large uteri appear to shrink more slowly and even with a 50% reduction in
volume, a very large uterus will remain. We have had several patients that were
disappointed when their uterus did not return to more normal size. There also have been
some reports that some patients with massive uterus have had persistent pain for months
after embolization and there is some concern that very large uteri may be more likely to
become infected. While there is no published data in this regard, we have made the
admittedly arbitrary judgment to refer this group for surgery.
It is also important to be certain that the symptoms the patient has are related to
fibroids. Fibroids do not cause heavy menstrual bleeding unless they are distorting the
endometrial cavity or the adjacent myometrium. Thus, smaller intramural fibroids
without this distortion may not be the cause of abnormal bleeding. Other causes to
consider include endometrial polyp, endometrial hyperplasia, adenomyosis, and
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dysfunctional uterine bleeding. We have seen many patients with trivial fibroids and
abnormal bleeding who have been referred for uterine embolization and it is important to
triage them appropriately to avoid a treatment failure due to misdiagnosis.
Similarly, the bulk symptoms that patients have are generally in direct relation to
their size and location. Again, very small fibroids without much bladder compression are
unlikely to be the cause of urinary symptoms.
All these recommendations are general in nature and each patient must be
evaluated individually. For this reason we again recommend that a cooperative
relationship be created with referring gynecologists. With appropriate collaboration,
patients will obtain the best therapy and the best outcome.
Summary
UAE is a great advance in the treatment of uterine fibroids, but as in all medical or
surgical therapies, it can only be effective when patients are properly evaluated and the
therapy offered is appropriate for that patient. In this presentation, we focused on issues
that are important in selecting patients for UAE and thus ensuring the best outcome. With
a collaborative relationship between gynecologists and interventional radiologists, the
patient will be offered the best choice of therapies and will therefore be best served.
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