Uterine Fibroid Embolization

Anatomy and Physiology

The uterine artery is a branch of the internal iliac artery (IIA). The IIA has 2 divisions, each having multiple branches and variations between individuals. The breakdown of these branches in their traditional/most common configuration is as follows:

Anterior Division

• Obturator artery
• Superior vesical artery
• Vaginal (females)/inferior vesical (males) artery
• Middle rectal artery
• Internal pudendal artery
• Inferior gluteal artery
• Uterine artery  

Posterior Division

• Superior gluteal artery
• Lateral sacral artery
• Iliolumbar artery 

The uterine artery is typically the IIA anterior division's first branch, whereas the inferior gluteal artery is usually its dominant (largest) branch. The second most common branching pattern is IIA trifurcation into the following:

• Uterine artery,
• IIA anterior division, and
• IIA posterior division.

The uterine artery has 3 segments:

1. The first segment descends along the pelvic sidewall to the broad ligament. The descending segment has no side branch arterioles. 
2. The second segment courses transversely toward the abdominal midline. A large side branch arteriole termed the cervicovaginal branch usually arises from the mid- to distal transverse segment but can also arise from the ascending segment. To avoid cervicovaginal necrosis, it is essential not to embolize this branch. 
3. The third segment ascends the uterine sidewall and gives rise to numerous arterioles that perforate the myometrium. 

Communication (anastomosis) between the uterine artery and the ovarian artery has been reported in almost half of female cadavers, but during angiography, such anastomoses are observed about 10% of the time. A classification for ovarian artery-uterine artery anastomoses has been proposed as follows:

• Type 1: The most common anastomosis is flow from the ovarian artery into the descending or transverse uterine artery segments.
• Type 2: An ovarian artery branch can bypass the main uterine artery to feed an ascending uterine artery branch and a fibroid.
• Type 3: In about 1 out of 20 women, an ovarian artery is absent, and the uterine artery supplies the ovary.

Converse to type 3, the ovarian arteries (instead of the IIA) rarely can supply the uterus directly with no uterine artery derived from the IIA (which is not allotted a type number but is similar to type 1). There are other rarer variants as well. The ovarian arteries typically arise from the aorta a few centimeters below the origins of the renal arteries. Their courses are often too tortuous to insert a standard catheter beyond more than a few centimeters. The clinical importance of the ovarian arteries for UAE is discussed below. In experienced hands, the uterine and ovarian arteries can be reached equally well via either leg (femoral artery) or arm (radial artery) access.[3]

Indications

Fibroid-Induced Symptoms in Premenopausal Women

The success of UFE (as measured by patient symptom control and post-procedure satisfaction) depends on appropriate patient selection based on pertinent positive and negative factors. Ideal candidates have no contraindications to UFE and characteristics including all of the following:

• Heavy regular menstrual bleeding or dysmenorrhea associated with intramural fibroids
• Premenopausal state
• No desire for future pregnancy

Fibroids characteristically cause heavy bleeding cycles, not irregular bleeding. Increased frequency of bleeding (shorter than 21-day cycles) and increased duration of bleeding (lasting longer than 10 days) are more likely to be related to endometrial pathologies such as polyps or cancer. Instead of or in addition to bleeding, fibroids can cause "bulk-related" symptoms such as pressure in the lower abdomen, legs, and back as well as dysuria (ie, nocturia, polyuria, incontinence). Results from prospective cohort studies and randomized controlled trials of women undergoing UFE have found a long-term improvement in bulk-related symptoms. Still, bulk-related symptoms generally are not as successfully treated via UFE as bleeding.[4][5] Candidates should be selected based on factors that predict tumor necrosis/shrinkage. For example, submucosally located and small fibroids tend to necrose well, while subserosally located and large fibroids tend to necrose poorly.[6]

Adenomyosis

Results from a retrospective review reported that 76% of 511 women who had undergone UAE for the treatment of adenomyosis reported significant improvement.[7] However, no study has yet included a control group to account for a placebo effect or to enable determination of a number needed to treat.  

Postpartum Hemorrhage 

Whether UAE is used as the first—or second-line invasive treatment for postpartum hemorrhage (ie, before or after surgical maneuvers) is currently institution—and/or gynecologist-dependent. Factors predicting UAE as an appropriate first-line treatment include abnormal placental attachment and abnormal clotting function (eg, as determined by serum fibrinogen/International Normalized Ratio). Persistent intraabdominal (or less likely transvaginal) bleeding after surgical treatment can indicate the bleeding to be from an extrauterine arterial source that may be better identified with arteriography. 

Prophylaxis of Intraoperative or Postoperative Bleeding

In some institutions, gynecologists request UAE as a prophylactic measure to attempt reduced perioperative hemorrhage, such as before fetal delivery in the setting of placenta accreta or previa [8] or during resection of benign or malignant uterine tumors.

Contraindications

Organizations have differing lists of "absolute" and "relative" contraindications to UFE. Contraindications from strongest to weakest include the following: 

• Viable active pregnancy
• Active endometritis
• Malignancy of the uterus/cervix without concurrent surgical treatment planned
• Menopausal bleeding of undiagnosed etiology
• Fibroid that is already infarcted (based on magnetic resonance imaging)
• Fibroid measuring <1 cm
• Fibroid that has pedunculated morphology (such as stalk width <50% of the maximum width; different percentage cutoffs may be used)
• Fibroid located in the cervix
• Concurrent use of a gonadotropin-releasing hormone analogue 
• Prior pelvic radiation therapy
• Immunocompromised state
• Fibroid causing the uterus's overall size to be equivalent to or larger than the expected size at 24 weeks of gestation (uterus craniad aspect of the uterus reaching the umbilicus)
• Severe contrast allergy
• Severe renal insufficiency while not receiving dialysis therapy
• Uncorrectable coagulopathy [9]

Patients desiring future fertility and patients with adenomyosis can be controversial candidates. The 2014 Society of Interventional Radiology (SIR) guidelines state that these patient types should be considered points of discussion, not patients with contraindications. The 2009 SIR guidelines state that "extensive endometriosis or adenomyosis" could result in UFE failure.[10][11] Evidence regarding these issues is discussed in the Clinical Significance section.

Reasons for some of the listed contraindications are briefly described as follows:

• There is an unlikely chance of successfully embolizing a fibroid with an extensive blood supply (usually proportional to fibroid size). In contrast, a subcentimeter fibroid is unlikely to be a source of symptoms. 
• Laparoscopic resection can prevent necrosed subserosal fibroid tissue sloughing off and forming an abscess nidus, a risk when a pedunculated fibroid's stalk is much thinner than the overall fibroid diameter.
• Cervical fibroids can often be removed transvaginally, which involves less risk of inadvertent injury to non-target tissues than arterial puncture and embolization.
• Drugs that affect endogenous gonadotropin-releasing hormone production should be stopped at least 3 months before UFE because they work in part by constricting the uterine arteries, which may preclude artery catheterization.

Equipment

In general, embolization of arteries feeding tumors is performed with particles, which are more likely than coils or glue to reach the capillaries and induce tissue necrosis and less than sclerosing chemicals to cause caustic side effects. Several types of particles are available, including the following:

• "Spheres,” made from tris-acryl gelatin (TAG) or other plastics,
• Nonspherical polyvinyl alcohol (PVA), and
• Spherical PVA

Regarding the size of particles used, no clinical difference was found between the use of 500 μm-or-smaller PVA compared to 500-to-700-μm PVA in a randomized controlled trial. However, it is general dogma that smaller particles result in better infarction rates, so smaller (300-500 μm) particles may be chosen if the microcatheter has been successfully placed well beyond the cervicovaginal branch; no uterine artery-ovarian artery anastomosis is visualized. Since particles tend to reflux from the artery selected and can inadvertently embolize other nearby tissues (such as the ovary), larger (700-900 μm) particles may be chosen if the catheter is unable to be placed well beyond the cervicovaginal branch or an ovarian artery anastomosis is visualized.[12][13][14] Regarding the shape of the particles used, multiple randomized controlled trials comparing microspheres to nonspherical PVA particles of the same size have found no difference in clinical outcomes.[15][16]

Preparation

Preparation for UFE typically involves a thorough assessment. The clinician should investigate the possible causes of the patient's symptoms to exclude pathologic and anatomic contraindications to UFE (as discussed above).

Cancer Screening 

Gynecologic screening for cervical cancer should be up to date. The American College of Obstetrics and Gynecology (ACOG) published its most recent guidelines in 2016 and reaffirmed them in 2024. ACOG recommendations include HPV testing as follows:

• At age 30 and thereafter every 3 years if a woman is HPV-positive or
• At age 30 and thereafter every 5 years if HPV-negative
• Stopping Papanicolaou smears at age 65 unless there is a clinical indication to continue

UAE is not an approved therapy for treating uterine cancer. Women with any abnormalities on screening magnetic resonance imaging that suggest cancer, particularly women older than 45, should undergo biopsy before UAE. 

Serum Parameters 

• Electrolytes
• Estimated glomerular filtration rate 
• Complete blood count 
• Platelet count >50,000/μL
• International Normalized Ratio ≤1.5
• Beta-human chorionic gonadotropin for pregnancy exclusion

Imaging

Magnetic resonance imaging provides significantly greater information for procedural planning than ultrasound (eg, size and position of fibroids, whether any fibroids have already self-infarcted, adenomyosis status) and should be performed prior to UFE.

Informed Consent

The SIR has made specific recommendations for informed consent to preserve patients' right to autonomy.[17]

• The 2009 guidelines stress the following:
• "Any treatment options should be presented with the understanding that additional consultation will be required for patients interested in gynecologic alternatives. Choice of embolic agents, routes of vascular access, and the anticipated use of an arterial closure device should be discussed. Descriptions of the expected admission process to the hospital (and by whom), the immediate post-uterine artery embolization recovery period, convalescence and medications at home, and the time expected away from work should also be made."
• "Written materials given at the time of consultation can enhance this process. Contact information should be given to patients so they can access a responsible physician on a 24-hour basis if they perceive a problem has arisen."[18]
• The 2014 SIR guidelines add: "Interventional radiologists should inform patients about... the possibility of a missed cancer diagnosis and a delay in definitive treatment."[19]

Pre-Procedure Care

Blood-borne pathogens can colonize UFE-induced necrotic tissue. 2018 SIR guidelines recommend that antibiotics, such as 1 g cefazolin or 500 mg levofloxacin, be given intravenously (IV) to reduce the chance of abscess development.[20] Some clinicians prescribe pain medication (eg, ketorolac 30 mg IV) before the procedure. If the patient undergoes procedural sedation, then precautions should be taken (eg, having the patient monitored by capnography at all times) to prevent respiratory depression and cardiac arrest. Some states require capnography by law, and the 2013 SIR standards of practice recommend it.[21]

Post-Procedure Care

Clinical factors that may need to be addressed after the procedure are as follows: 

• Pain
• Options for management include nonsteroidal anti-inflammatory drugs (NSAIDs) and/or opioids.
• One regimen includes ketorolac 30 mg given before the procedure and after, then 30 mg every 6 hours intravenously (IV) as an inpatient.
• Another regimen includes Ibuprofen scheduled during post-procedure observation and an opioid of choice available as needed for several days after discharge.
• Puncture site pain or leg pain is common, and it can result from injury to the medial femoral cutaneous nerve. This pain usually responds to NSAIDs and time. For severe pain thought to be related to nerve injury, gabapentin can be prescribed.
• If a patient has persistent (longer than 1 week) abdominopelvic pain, then imaging to investigate non-target embolization should be considered.
• Chronic pain syndromes (such as inflammatory bowel disease) may worsen after UFE.

• Pulmonary Embolism Prevention
• Sequential compression devices and prophylactic enoxaparin should be considered. 
• Patients have developed and died from pulmonary emboli after UAE.

• Bleeding
• Vaginal bleeding in the first week after therapy may include the following:
• Bleeding from endometritis, which is accompanied by flu-like symptoms and fever. 
• Bleeding after 1 week may indicate delivery of a sloughed fibroid. 

• Nausea
• After the procedure, nausea can be treated with ondansetron 4 mg IV, which is continued every 6 hours until discharge. 

• Hypertension
• Blood pressure often increases in the short term after embolization. 
• Potential sequelae of hypertension include pulmonary edema, myocardial infarction, and stroke. 

 Post-Discharge Communication

Communication between the patient and the clinician should continue during the week following the procedure; clinicians may wish to schedule a return clinic visit after 1 to 3 months.

Technique or Treatment

The technique for UAE is described as follows:

• Access the common femoral artery or radial artery and insert a sheath.
• Obtain an arteriogram to demonstrate the following:
• The uterine artery origins
• Collateral arteries supplying the uterus (which may have already been shown on the pre-procedure magnetic resonance imaging)
• Place a catheter with a directional tip into the IIA anterior division.
• Advance a smaller catheter (a microcatheter) coaxially through the directional catheter into the uterine artery horizontal segment beyond any cervicovaginal branch(es). The arterioles supplying fibroids are usually too small to be catheterized or even seen. 
• Obtain another arteriogram through the microcatheter to identify any collateral branch(es) supplying the ovaries/bladder/vagina that might affect choices of which particles to use for embolization.
• Embolization should be performed with particles sized for the best combination of embolic effect and limited risk of inadvertent (non-target) tissue necrosis.
• Obtain final images showing the state of intra-arterial contrast flow to the uterus.
• Repeat the procedure on the contralateral side of the uterus.
• Obtain hemostasis at the site(s) of the arterial puncture(s).

Variables not yet shown by randomized controlled trials to have 1 alternative superior to the other are many and include the following:

• Performing bilateral femoral artery punctures vs a single femoral artery puncture
• ... to decrease the difficulty of contralateral uterine artery catheterization and overall procedure time, versus reducing the likelihood of artery access site complications.
• Performing the initial or final overview arteriogram from the aorta vs the common iliac artery
• ... to identify an ovarian artery that feeds a fibroid (or other variant anatomy) vs to reduce contrast load.
• Administering medications during the procedure, such as
• Nitroglycerin to prevent/treat arterial spasm.
• Lidocaine intra-arterially to minimize post-procedure pain.
• Ketorolac intravenously to reduce post-procedure pain.
• Selecting a given embolization endpoint as follows:
• Seeing contrast stasis in the uterine artery for 5 to 10 heartbeats vs
• Visualizing contrast refluxing toward the uterine artery origin vs
• Achieving a uterine artery subjectively "pruned" appearance

Complications

While UFE is generally considered a safe and effective treatment for fibroids, it carries potential risks and complications like any medical procedure. Understanding these complications is crucial for healthcare professionals and patients to ensure informed decision-making and optimal management. The overall complication rate differs according to published reports and can be as high as 40% to as low as 5%.[22]

Major Complications

Some significant complications can occur, requiring careful monitoring and management to minimize risk and ensure patient safety.

• Death (<1/1000)
• Need for surgery due to a complication of the procedure, such as arterial perforation (2-3 in 100)
• Abscess or other severe intrauterine infection (1 in 100)
• Pulmonary embolism
• Subsequent pregnancy-related complications, such as spontaneous uterine rupture during subsequent pregnancy or placenta accreta
• Premature ovarian failure
• Buttock or leg ischemia

Death

Often, the mechanism of death is via sepsis or pulmonary embolism.

Infection-Spectrum Findings

Postembolization syndrome is the most common adverse event and can manifest with signs and symptoms as follows:

• Pain,
• Low-grade fever,
• Malaise, and
• Nausea/appetite loss

Bacterial endometritis can manifest with the following:

• Pain
• Fever
• Vaginal discharge that has the smell or appearance of infection
• Leukocytosis

Noninfectious endometritis can manifest as follows:

• Pain
• Low-grade fever
• Vaginal discharge that is typically watery
• Leukocytosis that begins days to weeks after the procedure

Immediately after UFE, imaging findings do not reliably differentiate infected fibroids from non-infected fibroids.  

Amenorrhea Spectrum Findings

Amenorrhea of any kind occurs in less than 10% of UAE cases when considering patients treated for all UAE indications; it is much more likely in patients older than 45. Amenorrhea is usually limited to a few menstrual cycles and is not typically associated with increased follicle-stimulating hormone (FSH) levels or menopausal symptoms. Premature ovarian failure is defined as the presence of the following: 

• Persistent amenorrhea
• Increased FSH levels
• Symptoms of menopause
• Night sweats
• Mood swings/irritability
• Vaginal dryness

Fibroid Expulsion 

Expulsion is a detachment of fibroid tissue from the uterine wall and its subsequent transvaginal passage. This most commonly occurs with submucosal fibroids that have thin points of attachment. Surgical intervention may be necessary to relieve persistent discomfort and remove the tissue. This process may present as follows:

• Pain/uterine contractions
• Low-grade fever
• Vaginal discharge that lacks the smell or appearance of infection
• Nausea/vomiting 

Angiography Complications

There are many types of angiography complications, but the most common include the following:

• Hematoma
• Arterial dissection
• Pseudoaneurysm
• Contrast-induced nephropathy

Other Adverse Events

Some patients may encounter rare adverse events. These less common issues require attention to manage and ensure the best possible patient experience and outcome.

• Patients may have pain that is atypical of post-embolization syndrome. In these circumstances, contrast-enhanced computed tomography or magnetic resonance imaging may be used to assess for findings of non-target tissue embolization or a fibroid sloughed into the pelvis.
• There have been reports of petechial rash on the torso and limbs (1% to 7%) after UAE.
• Sterilization can occur due to ovarian embolization. Results from a Cochrane systematic review of 15 prospective cohort studies and randomized controlled trials found that loss of ovarian function after UAE occurred primarily in women older than 45.[23]
• Immediate injury from radiation is unlikely, as the radiation doses typical for UAE are an order of magnitude less than those required to produce radiation burns.

Clinical Significance

UFE Success and Failure

SIR guidelines indicate that about 90% of women undergoing UFE should expect reduced bulk symptoms, and more than 90% should expect cessation of abnormal uterine bleeding.[10]

Causes of UFE failure include, but are not limited to, the following:

• Poor patient selection
• Large fibroids
• Inability to catheterize the uterine arteries
• Incomplete artery embolization
• Arterial spasm leading to poor flow of embolic material
• Clumping of embolic material leading to a false embolization endpoint
• Uterus anatomic variants
• Presence of essential collateral arteries (eg, ovarian arteries) feeding the uterus
• Coexisting adenomyosis or leiomyosarcoma
• Recanalization of embolized arteries

For the control of postpartum hemorrhage, emergently performed UAE has about a 90% to 95% success rate (with failures usually requiring hysterectomy). The morbidity with UAE is expected to be less than with emergent laparotomy. As with many minimally invasive procedures, UFE is a middle-of-the-spectrum option; it is less likely to achieve treatment goals than surgery, and has a higher risk of complications than pharmacologic alternatives. Outside the setting of fibroid treatment, no randomized controlled trials compare UAE to other treatments, and thus, no guidelines based on level 1 evidence. Hence, the following discussion focuses on treatment for fibroids. 

Trials and Guidelines

There has not been a randomized controlled trial comparing UFE vs endometrial ablation alone or medication alone. A pilot trial comparing UFE vs gonadotropin-releasing hormone analogs (GnRHana) in the preoperative setting found UFE to have a clinical advantage.[24] A brief overview of medical therapy for fibroids shows the following:

• NSAIDs are more effective at decreasing fibroid-related menstrual pain and bleeding than a placebo but less than tranexamic acid or the levonorgestrel-releasing intrauterine device.[25]
• GnRHana can shrink fibroids and limit menorrhagia. Because they cause osteopenia with long-term use (based on data collected in the 1980s and 1990s), GnRHana can only be used for 2 to 6 months and when there is a clear therapeutic goal, such as when follow-up surgery is planned or when menopause is incipient.[26][27]
• Gonadotropin-releasing hormone antagonists (GRHant) avoid the symptom flare that is associated with GRHana, but they also cause osteopenia with long-term use. Rebound fibroid growth occurs after cessation of both GRHana and GRHant.
• Progesterone-receptor antagonists (PRant), such as mifepristone and ulipristal acetate, can decrease fibroid symptoms without osteopenia.[28] A woman undergoing therapy with a PRant cannot become pregnant, which is a goal for some women who simultaneously want therapy for fibroids. 

About 10 randomized controlled trials (RCTs) involving over 1000 women have compared UFE to different types of fibroids surgery. These trials have compared UFE against abdominal hysterectomy, myomectomy, endometrial ablation, or some combination thereof. In a meta-analysis of UFE vs all types of surgery, Gupta et al found no significant difference in patient satisfaction or major adverse events between UFE and any type of surgery. UFE had a higher rate of minor complications and necessity for additional surgical interventions. Gupta calculated that within 2 years of initial therapy, 7% of women after hysterectomy or myomectomy require further surgery, whereas 15% to 32% require surgery after UFE. Gupta concluded that, compared to all surgical approaches, patients undergoing UFE could expect a lower likelihood of needing a blood transfusion,  shorter procedural time, shorter hospital stay, and faster resumption of usual activities.[23]

The first RCT, Embolization versus Hysterectomy for Symptomatic Uterine Fibroids (also called the EMMY trial), enrolled patients between 2002 and 2004. This multicenter trial had a follow-up duration of 10 years, the most extended follow-up of any such RCT to date. Enrolled patients had both fibroids and menorrhagia and were all eligible for hysterectomy. One hundred seventy-seven patients were randomized to UFE (n= 88) or hysterectomy (n= 89). Ten years after treatment, 33% of those with UFE had undergone secondary hysterectomy for recurrent symptoms (8% of initial hysterectomy patients also required a second procedure). Still, there were no significant differences between hysterectomy and UFE concerning successful eradication of pain, bulk-specific complaints, complications, or overall satisfaction. The study authors concluded that hysterectomy is better at achieving a certain cure for bleeding problems. However, patients with the appropriate combination of indications and lack of contraindications should be allowed to choose UFE instead of a hysterectomy.[29]

The Randomized Controlled Trial of Embolization versus Surgical Treatment for Fibroids (REST) is the largest RCT (157 patients) compared to UFE and hysterectomy to date. This multicenter trial compared all surgical interventions to UFE and achieved 80% power with a 1-year follow-up. The study found no statistically significant difference between UFE and surgery in quality of life or major complications. UFE had a higher minor complication rate (34% vs 20%) but also had a statistically significant reduced length of hospitalization, 24-hour pain score, and cost.[30]

Evidence regarding UFE vs myomectomy alone includes the following:

• In an RCT by Mara et al, patients having intramural fibroids >4 cm were randomized to UFE (n= 58) or to myomectomy (open or laparoscopic according to surgeon preference; n= 63) and followed for 2 years. 
• This study is the primary study used as the rationale for making myomectomy the first-line invasive therapy in women who still wish to conceive, because 50% of UFE vs 78% of myomectomy patients were able to conceive. In this study, UFE had a 95% confidence interval of increased relative risk for inability to conceive (1.11 to 4.44) and miscarriage (1.25 to 6.22).[31]
• However, Gupta (2014) included Mara's patients with those who had undergone myomectomy from other RCTs and did not reproduce the statistically significant confidence interval. Gupta deemed the evidence that myomectomy provides a fertility benefit over UFE to be "low-quality evidence" that "should be regarded with extreme caution."[23] 
• Another later systematic review of RCTs and (non) RCTs also concluded that there is currently insufficient evidence that myomectomy improves fertility compared to UFE, whether by the laparoscopic or open approach.
• In 2012, an RCT of 163 patients found no difference in quality of life between myomectomy and UFE at 1 year.[32]
• Initial results of the Uterine-Artery Embolization or Myomectomy for Uterine Fibroids trial (also called the FEMME trial) were published in 2020, with 4-year follow-up data published in 2022 and 2023 (in 2 different journals).[33][34][35] This RCT of 254 women compared UFE to myomectomy alone and found a slight improvement in quality of life with myomectomy at 2 years that became statistically insignificant at 4 years.

ACOG recommends transvaginal approaches for fibroids as the first-line consideration when an invasive procedure is planned. ACOG concludes that UFE "is recommended... (for) treatment... in patients who desire uterine preservation and are counseled about the limited available data on reproductive outcomes."[36] 

Enhancing Healthcare Team Outcomes

UFE is usually performed by an interventional radiologist and less commonly by a vascular surgeon. The obstetrician/gynecologist should be able to educate the patient about the pros and cons of this technique compared to surgical and/or medical treatments that a surgeon or other primary care physician can offer. A multidisciplinary approach to patient education should be followed.[37][38]

After the procedure, the nurse caring for the patient is responsible for knowing what symptoms and signs to look for regarding complications and making initial treatment recommendations or decisions, such as when to administer clinician-prescribed analgesics and other medications. Pharmacists also play a vital role in ensuring appropriate medication management, particularly pain management. The interprofessional team members must work together and communicate constructively. Such communication can enable the team to achieve safe outcomes, meet established healthcare standards, and achieve patient-centered care.[39] Additional ethical reasons for this recommendation have been reviewed previously.[40]