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Fibroid Treatments Demystified, Part III: Focused Ultrasound

 

Among the hysterectomy alternatives available to women with fibroids is the high intensity focused ultrasound approach (HIFU), more specifically identified as Magnetic Resonance Guided Focused Ultrasound (MRgFUS). MRgFUS is a thermoablative technique that destroys fibroids by focusing a high-intensity beam of ultrasound energy on specific tissue.

Performed as an outpatient procedure, the focused ultrasound method is entirely non-invasive: no insertion of a catheter or needle is necessary, and no cutting is involved. The MRgFUS procedure is approved by the FDA for use in premenopausal women with symptomatic fibroids who have completed childbearing. While certain limitations prevent the technique from being widely used or universally appropriate, its effectiveness in reducing symptom severity and improving patients’ quality of life has been demonstrated in a variety of cases.

How Focused Ultrasound Works

MRgFUS is performed without anesthesia, under conscious or no sedation, by a physician, with the patient in an MRI unit. Using magnetic resonance imaging (MRI) allows the practitioner to achieve clear visualization of the reproductive organs and provides real-time thermal monitoring, enabling the practitioner to optimize the ultrasound treatment’s ablative effects. The physician then directs high intensity ultrasound waves to a small area of fibroid tissue, destroying the targeted tissue with thermal energy. The ultrasound beam has a frequency range of approximately 1–1.5 MHz, which is on the low end of the spectrum for diagnostic ultrasonography. Immediately following the treatment, the patient is injected with an MRI contrast agent called gadolinium, which allows the practitioner to view the treatment’s impact on the fibroid’s vascular structure.

Treatment Outcomes

Patients who undergo a focused ultrasound procedure typically experience rapid recovery. Symptom improvement is usually seen within the first three months post-procedure, and research has shown this improvement to be sustained through 24 to 36 months in most cases.

While generally effective, focused ultrasound therapy is limited in its usefulness. For example, MRgFUS cannot be performed effectively if certain kinds of structures—such as the bowel, the pelvic bone, a skin fold, or an implanted device — are obstructing the path to the fibroid. Furthermore, characteristics of the fibroids themselves—including size, vascularity, and placement—can sometimes make them difficult to treat. The maximum size treatable is uncertain; however, most practitioners surveyed indicated that fibroids larger than 10cm are generally more difficult to treat with focused ultrasound.

Since focused ultrasound is limited in its ability to target all fibroids, repeated treatments are often required: Stewart et. al found that, “With minimal [initial] treatment the probability of additional treatment exceeds 50% at 24 months, but this is substantially reduced with increasing ablation”.

The MRgFUS procedure is not widely available, mostly due to cost: few clinics are equipped with the high-priced system, and insurers are not typically inclined to cover costly procedures. On the positive side, short-term morbidity is low and the recovery time is short. No specific pattern of complications with pregnancy has been identified; however, the procedure is not indicated for women who plan to get pregnant. For others who are seeking a uterine-sparing, non-invasive treatment to relieve symptomatic fibroids, the focused ultrasound approach may be a viable option.

 

SOURCES:
Stewart, E. et al. “Clinical Benefit of Focused Ultrasonography”, Obstetrics & Gynecology. Aug. 2007; Vol.110(2):279-287
InSightec, “MR Guided Focused Ultrasound for Uterine Fibroids”, Information for Prescribers: ExAblate Version 2.46. Revised Nov. 2004
“HIFU Treatment (High Intensity Focused Ultrasound).” Uterine Fibroids. Retrieved June 26, 2015. http://www.uterine-fibroids.org/hifu.html.

 

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Fibroid Treatments Demystified, Part I: Uterine Artery Embolization

Many women of reproductive age seek uterine-sparing methods of fibroid treatment: uterine artery embolization (UAE), sometimes called uterine fibroid embolization (UFE), is one of the hysterectomy alternatives available to women with fibroids.

How UAE Works

Uterine artery embolization (UAE) is a minimally-invasive procedure that is performed by an interventional radiologist. UAE treats fibroids “in situ”, meaning ‘in place’, by cutting off their blood supply and causing them to die from what is known as “ischemic necrosis”. To do so, an interventional radiologist inserts a catheter through the femoral artery (located in the upper thigh) and into the uterine artery, which supplies blood to the uterus. A type of material known as an “embolic agent” is then injected through the catheter, into the blood vessels that supply blood to the fibroids. Typical embolic agents include polyvinyl alcohol (PVA), gelatin sponge plegets, or gelatin microspheres. Once injected, particles of the agent block the blood supply to the tiny arteries that carry blood to the fibroids. Without adequate blood flow, the fibroids shrink and, ultimately, die.

Treatment Outcomes

UAE is successful in diminishing fibroids and associated symptoms in an estimated 85% of cases. For patients who are looking for a minimally invasive fibroid treatment, embolization’s non-surgical approach is appealing. The recovery period is generally short, though it is notoriously painful. Fred Burbank, author of Fibroids, Menstruation, Childbirth, and Evolution, states “nearly all women who undergo [UAE] have severe pelvic pain generally lasting 4 to 6 hours, but others, lasting up to a day” (p.124). The American Society For Reproductive Medicine also notes, “patients typically experience several days of pain after the procedure”. Many women are hospitalized overnight for pain control.

The incidence of fertility-compromising outcomes has called into question the appropriateness of the procedure for women seeking to get pregnant, though additional research is needed to assess the risk. Here’s what researchers do know: once the embolic agent has been injected, the particles stay in the body. In some cases, those particles can migrate to the ovarian blood supply, compromising fertility and triggering the onset of menopause. Burbank describes the physiological process after injection of the embolic agent:

Anatomically, connections exist that allow particles injected into the uterine artery to reach any structure supplied by branches of the uterine artery. The physiology of blood flow from the uterine artery to its branches determines the relative number of particles that reach the myometrium, fibroids, and the ovaries. Injected particles are indifferent to where they go.(p.111) A significant number of women who undergo UAE become amenorrheic (cease to have periods)as a result of the procedure; however, research has indicated that younger patients see fewer complications of this nature. A longitudinal study by Goodwin et. al found that, at 36 months post-procedure, approximately 85% of patients had no intervention but 28.6% of UAE patients were amenorrheic with the largest proportion(78.9%) of patients over the age of 45.

UAE isn’t right for everyone: women with fibroids should talk to a gynecologist about the risks and benefits of UAE and other available fibroid treatment options, before seeking treatment. However, as one of the less invasive methods for treating fibroids, UAE helps meet the growing demand for alternatives to hysterectomy.

SOURCES:

  1. American Society for Reproductive Medicine, “Treatment of Uterine Fibroids”, ReproductiveFacts.org: 2011. Retrieved May 25, 2015, from http://www.reproductivefacts.org/FACTSHEET_Treatment_of_Uterine_Fibroids/
  2. Goodwin, S. et al./Fibroid Registry for Outcomes Data (FIBROID) Registry Steering Committee and Core Site Investigators.”Uterine Artery Embolization for the Treatment of Leiomyomata: long term outcomes from the FIBROID Registry”, Obstetrics & Gynecology, Jan 2008; Vol 11(1):22-33
  3. Burbank, F. Fibroids, Menstruation, Childbirth, and Evolution, p. 110. Wheatmark, 2009. Tucson, AZ.

 

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