Uterine Artery Embolization (UAE) for Uterine Fibroids

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What is Uterine Artery Embolization (UAE) ?

UAE - Outcome and Success Rate

Complications of UAE

Conclusions

What is Uterine Artery Embolization (UAE)?

Uterine artery embolization (UAE) is a radiological procedure recently introduced as an alternative treatment for symptomatic uterine fibroids. The American College of Obstetrics and Gynecology cautions about its potential for infection and other serious complications requiring emergency surgery.

The radiologist introduces a catheter, usually through the right femoral artery, into each of the two uterine arteries, which supply blood to the uterus and, in turn, to the fibroids. A solution containing small particles is injected into the uterine arteries. The particles occlude the branches of the uterine arteries (blood outflow) and thereby drastically reduce blood supply to the uterus and the fibroids. The procedure is usually done under conscious sedation and local anesthesia, without general anesthesia.

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UAE - Outcome and Success Rate

Six months after UAE the average fibroid is reduced in size by 40-60%. Reportedly, UAE reduces uterine bleeding and symptoms related to uterine size such as urinary frequency and pelvic pain. However, the studies reporting reduction in bleeding have used subjective patient assessment of bleeding with no objective measurements of actual blood discharged. Also, with very large fibroids (uterus larger than 24 weeks’ gestational size), myomectomy provides better relief of bulk symptoms and abdominal protrusion than the average 40% reduction in uterine volume achieved by UAE. The purported advantages of UAE compared to myomectomy include avoidance of abdominal surgery, abdominal scar, and general anesthesia, as well as diminished risk of significant blood loss, shorter hospital stay and shorter recovery time are further supposed benefits of UAE vs. myomectomy.

Recent studies found that 22% of patients undergoing UAE required hysterectomy or myomectomy.  Additional patients required hysteroscopy.  The reasons for the hysterectomy were continued heavy bleeding, pain and bulk related symptoms. Hysteroscopy was required because of vaginal discharge and many of those patients ended up needing hysterectomy.

Magnetic Resonance Imaging (MRI) during the pre-UAE evaluation may help avoid a potentially ineffective UAE in up to 20% of patients who are referred for UAE. MRI may detect a pedunculated submucous fibroid (see below), which is better treated with hysteroscopic resection; non-viable fibroids (with poor vascularity) which are unlikely to shrink after UAE; and significant adenomyosis where results of UAE are poor (see below). When UAE is performed because of pelvic pain in a woman with fibroids and endometriosis, the UAE is unlikely to resolve the pain which is more often caused by the endometriosis.

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Complications of UAE

1. Procedure-related complications.

• Infection at catheter insertion site in the groin.
• Hematoma (bleeding) in the groin, secondary to the puncture.
• Contrast reactions (and allergic and other adverse reactions) due to the radiographic contrast medium.
• Pseudoaneurysm - abnormal collection of blood communicating with the groin artery puncture site, which may require further intervention to repair.
• Arterio-venous fistula - an abnormal communication between artery and vein in the groin secondary; to the trauma of groin catheterization which may require further intervention to repair.

2. Unintended embolization of other abdominal arteries causing reduced blood supply to the organs supplied by those vessels.

Examples include: Reduced blood supply to the buttocks with muscular pain and skin sloughing, reduced blood supply to the bladder with damage to the bladder wall, reduced blood supply and damage to the ovaries and/or vaginal labia.

3. Post- embolization pain.

UAE is usually moderately to extremely painful, necessitating in-hospital pain management with intravenous narcotics for at least several hours. It is not unusual for a short hospital stay to be required for pain and nausea control.

4. Post-embolization syndrome.

This condition includes ischemic pain (due to lack of oxygen to tissues), nausea, and/or vomiting, malaise, low-grade fever, and elevated white blood count. This syndrome occurs to varying degrees in all patients, but in over 50% of patients it is a significant clinical problem. Post-embolization syndrome starts one to five days after UAE and typically lasts 24 to 48 hours, sometimes longer. In 10-15% of patients, this problem requires readmission to the hospital. This condition must be distinguished from the more serious complication of sepsis.

5. Sepsis

This is a serious bacterial infection that spreads from the uterus to the blood stream. If not recognized early and treated effectively it is potentially fatal. Sepsis is suspected when fever persists beyond the 24 to 48 hours typical of post-embolization syndrome. Sepsis is more frequent when UAE is performed on a very large uterus (more than 20 cm in height, when a single fibroid is larger than 9 cm in diameter, or when there is a large submucous fibroid (fibroid projecting into the uterine cavity). Also, in the presence of Chronic Pelvic Inflammatory Disease or active sexually transmitted disease, UAE should be avoided. There have been case reports of death due to sepsis or pulmonary embolism.

6. Premature ovarian failure.

Because the blood supply to the ovaries is partially from the uterine arteries, the procedure of UAE invariably diminishes the blood supply to the ovaries and results in some reduced ovarian function. This is evidenced in the almost universal rise in serum FSH (follicle stimulating hormone) following UAE. FSH levels are an indirect measure of ovarian reserve. The number of ovarian follicles in the ovaries declines constantly from birth to menopause. When the ovaries are depleted of follicles they malfunction and menopause begins. In fact, 2.4-15% of UAE patients go into premature menopause, especially in women around 40 years of age. In patients younger than 40 who have UAE, there is also evidence of accelerated depletion of ovarian follicles which could result in earlier menopause.

7. Reduced fertility after UAE.

To date there have been only a few anecdotal reports of successful pregnancies after UAE. On the other hand, small studies report a dramatic increase in miscarriages and premature deliveries after UAE. The decrease in uterine blood flow after UAE is likely to result in reduced endometrial receptivity and infertility as well as intrauterine growth retardation. The decrease in ovarian reserve (manifested by elevation in FSH) indicates a decrease in ovarian follicular reserve, leading to premature menopause in the more severe cases. Recent studies have shown that UAE causes ovarian damage, as evidenced by steeper than normal age-related decline in anti-Mullerian hormone levels.  Anti-Mullerian hormone levels are relatively new and reliable quantitative marker of ovarian reserve.  This marker reflects diminished fertility.  This should matter to women who wish to preserve fertility.  In addition, compared to myomectomy, UAE significantly increases the risk of complications in future pregnancies such as spontaneous abortion, premature delivery, and malpresentation as well as post partum hemorrhrage. These facts have led most authorities to consider a woman's desire to preserve her fertility potential as a contraindication to UAE. The American College of Obstetrics and Gynecology considers UAE to be contraindicated in women wishing to retain fertility.

8. Necrosis of pedunculated (on a stalk) subserous fibroid.

A fibroid growing out of the uterus on a stalk may become necrotic (due to cell death) after UAE. This could lead to pain, adhesions and infection. Some have suggested performing laparoscopic myomectomy of such a fibroid after the UAE.

9. Necrosis of a pedunculated submucous fibroid.

Following UAE, a submucous fibroid attached on the inside of the uterus by a stalk (intra-cavitary fibroid) may become necrotic and be extruded through the cervix. This is accompanied by a foul smelling discharge, pressure, and sometimes, urinary retention. The fibroid may be detached spontaneously, but a vaginal myomectomy in the operating room may be required. Because of this concern with respect to submucous fibroids, some have suggested performing hysteroscopic myomectomy after the UAE. However, the presence of a potentially problematic submucous myoma may not become evident until after UAE when this complication occurs.

10. Delay in the diagnosis of leiomyosarcoma.

In less than 1% of women with fibroids, one of the fibroids is malignant (leiomyosarcoma). This highly malignant tumor cannot be definitely diagnosed or ruled out by preoperative imaging studies. Therefore, in a very small percentage of cases, UAE may result in delayed diagnosis and treatment of a potentially aggressive cancer.

11. Failure to diagnose adenomyosis prior to UAE.

Failure rates of UAE in the treatment of adenomyosis are high. Consequently, many experts consider adenomyosis as contraindication to UAE. Many require pelvic MRI prior to UAE in order to rule out adenomyosis (as well as pedunculated subserous and submucous fibroids).

12.  UAE may cause dense intra abdominal adhesions.

Because of tissue necrosis predisposing to adhesion formation.  Among women undergoing hysterectomy for failed UAE 20% were found with dense adhesions between the fibroid, uterus and surrounding organs, such as bowel.  Adhesions were more common in the presence of a large fibroid.

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Conclusions

UAE is still an investigational procedure in the treatment of fibroids. There is no long-term follow up available. Its short term failure rate (defined as continued symptoms, undergoing subsequent hysterectomy, or patient's refusal to recommend it to another woman) is about 15%. In the presence of a fibroid larger than 8.7cm, the failure rate is higher than 15%; and for every additional 1 cm increase in diameter there is an additional increase of 10% in the failure rate. In one study with at least five years of follow-up, the repeat intervention rate, i.e., the medical need for additional surgical intervention such as hysterectomy or myomectomy, has been 19.7%. Another recent study found that following UAE, 23.5% of patients required hysterectomy within two years resulting in a success rate of 76.5%. This success rate is much lower than reported in earlier studies which reported a subsequent hysterectomy of 1.5-4.5%. Ohter studies reported a hysterectomy rate of 13.7% and 15.2%. Although UAE is a good alternative for a select group of women, it is by no means a risk-free or pain-free procedure. In a large study of UAE (followup of at least one year) compared to abdominal myomectomy, UAE patients were more likely to require subsequent invasive treatment (abdominal hysterectomy or repeat UAE) - 20% versus a single myomectomy patient.

A woman desirous of having UAE must be thoroughly evaluated to rule out the numerous conditions that would render UAE more risky or contraindicated (endometrial biopsy to rule out endometrial hyperplasia, allergy to contrast medium, kidney problems, poorly controlled diabetes mellitus, very large uterus, a large individual fibroid, a large submucous fibroid, a subserous fibroid on a stalk, adenomyosis, rapid tumor growth as a possible indicator of cancer, desire for future fertility, elevated FSH levels as an indicator of low ovarian reserve). The patient must be thoroughly counseled with regard to the potential complications. In a patient who is able to undergo surgery by an expert in myomectomy, my experience dictates that myomectomy is the definitive and preferred treatment, which preserves uterine and ovarian function.

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© COPYRIGHT 1996-2012 ALL RIGHTS RESERVED MICHAEL E. TOAFF, MD, MSc

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