Keywords
fibroid - uterus - menorrhagia - radiofrequency ablation - fertility - surgery - interventional radiology
Uterine fibroids, also referred to as leiomyomas or myomas, are the most common benign neoplasm of the female pelvis and have a lifetime prevalence exceeding 80% among African American women and approaching 70% among Caucasian women.[1] Approximately 50% of women with fibroids experience symptoms which can be classified into the following categories: heavy or prolonged menstrual bleeding, bulk-related symptoms such as pelvic pressure with bladder and bowel dysfunction, reproductive dysfunction (e.g., infertility or obstetric complications), and pain.[2] The choice of treatment is primarily guided by the type of symptoms in the individual patient and whether they prefer to retain fertility.[3] Hysterectomy provides definitive resolution of fibroid symptoms and has long been known to be the most common treatment option. However, this procedure is invasive with a long recovery window. For patients who do not desire definitive surgical management via hysterectomy or do not use or respond to medical management, alternative uterus-sparing procedures are highly sought due to their less invasive and fertility-sparing nature.[3]
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Resective options include myomectomy via transabdominal, laparoscopic, and hysteroscopic approach. Myomectomy is a surgical procedure to remove uterine fibroids while leaving the uterus intact. In laparoscopy and transabdominal approach, complications include hemorrhage, conversion to hysterectomy, infection, and adhesive disease.[5] Hysteroscopic complications include uterine perforation, urinary tract or bowel injury, cervical laceration, excessive fluid absorption, and embolism.[6] Nonresective options include uterine artery embolization (UAE), magnetic resonance high-intensity focused ultrasound (MR-HIFU), and radiofrequency ablation (RFA). Common complications with UAE include pelvic pain, fever, and vaginal discharge. In this article, we will focus on the utilization of RFA in managing uterine fibroids, as this technique has made the most recent advances as a safe and effective minimally invasive treatment option. Throughout this review, we will compare RFA to myomectomy given its common overlapping indications, similar procedure characteristics, and due to more favorable patient-focused outcomes compared to other alternatives.[7]
History of Radiofrequency Ablation
History of Radiofrequency Ablation
RFA has had broad use in various surgical subspecialties prior to implementation in gynecology. In the 1990s, RFA was first suggested to ablate liver tumors. Since then, RFA has been applied to treat cancers in the adrenal gland, breast, kidney, bone, lung, pancreas, and thyroid.[8]
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[11] In 2002, Bruce Lee, MD, was the first to publish laparoscopic ultrasound-guided RFA of uterine fibroids as a uterine-conserving procedure, known as the Acessa procedure (Hologic; Marlborough, MA).[12] He had considered other forms of fibroid destruction including cryosurgery, microwave, and laser probes but elected to develop a system specifically to treat uterine fibroids using radiofrequency energy due to its safety profile and reliability in ablating fibroids up to 7 cm in diameter.[13] This device received U.S. Food and Drug Administration (FDA) approval in 2012. Another technology focused on a transcervical approach to RFA began its development in 2005. Sonata (Gynesonics, Redwood City, CA) is also an RFA device that uses an incisionless transcervical approach to ablate fibroids. This device received FDA approval in 2018.
RFA is a “volume reduction” procedure. While it can help some women avoid hysterectomy, the uptake of the procedure broadly has not yet soared and is less frequently utilized than UAE. Contributing to this may be that the treatment is not yet been approved for fertility preservation by the FDA. Furthermore, not all insurance companies will cover the cost of the procedure. Healthy, full-term pregnancies after the procedure have been reported, although more data are needed. Researchers are continuing to collect data to provide a more thorough assessment of how the treatment affects fertility.[14]
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How Does Radiofrequency Ablation Work?
How Does Radiofrequency Ablation Work?
Radiofrequency ablation uses elevated temperature to produce tissue destruction. Heat may be applied by direct thermal conduction or by ultrasound or electromagnetic (RF) energy. Radiofrequency waves, with its long wavelength, low frequency, and low energy on the electromagnetic spectrum (between 3 kHz and 300 GHz), are an ideal candidate for controlled and predictable ablation of tissue. Of note, medical procedures typically use frequencies between 450 and 500 kHz.[13]
Placement of the electrode into a target tissue results in transmission of the current through the tissue with a particular point of entry. The current then travels to the electrode return pads and back to the generator, completing the circuit. Heat is created through ionic (Na, K, Cl) friction and spreads by simple thermal conduction, producing a volumetric ablation through coagulative necrosis.
Human cells die nearly immediately at 60 °C; proteins start to denature once a fibroid becomes appropriately heated to this temperature. Higher temperatures between 60 and 99 °C are desirable to produce a larger ablation volume in a shorter amount of time.[9] However, temperatures greater than 100 °C produce local tissue charring and vaporization which cause lower current density and insulation, decreasing both heat generation and conduction. This can potentially result in incomplete ablations. Therefore, a slow, methodical deposition of energy is more effective in ablating target tissue rather than a rapid and high temperature rise.[16]
Types of Radiofrequency Ablation
Types of Radiofrequency Ablation
Both laparoscopic RFA and transcervical RFA are safe and effective procedures once proceduralists have been appropriately trained on their use. RFA can be quickly learned with a majority of gynecologists noting confidence and no increase in adverse events compared to experienced RFA surgeons after performing their fifth proctored procedure.[17] In contrast, myomectomy and hysterectomy require 40 to 50 cases to achieve surgeon competency. While both technologies utilize ultrasound guidance to direct placement of monopolar, expandable, radiofrequency electrodes into myomas, they do differ in how they achieve this.
Laparoscopic RFA (Acessa Procedure)
The Acessa procedure utilizes laparoscopic radiofrequency volumetric tissue ablation by utilizing low-voltage, high-frequency alternating currents ([Fig. 1]). Two standard laparoscopic ports are placed, a 5-mm umbilical port for the laparoscope and a 10-mm suprapubic port for the ultrasound transducer. Since the laparoscopic ultrasound transducer is placed directly on the uterine surface, the image produced has significantly greater resolution which is beneficial to locate fibroids that may have otherwise gone undetected. Next, the handpiece is placed percutaneously through a small skin incision, advanced to the fibroid, and carefully inserted 1 cm into the fibroid capsule. Depressing the foot pedal initiates the ablation. The electrode array is deployed into the fibroid. The elevated temperature from the device causes tissue destruction by heat created through ionic friction which then spreads by conduction resulting in cellular death.[6] After the ablation duration is complete, the foot pedal is again depressed to stop the procedure. The electrode arrays are then retracted, and the handpiece tip is allowed to cool for 60 seconds prior to removing from the target tissue.[18] Patients return home the same day and require only NSAIDs for pain management.
Fig. 1 Laparoscopic radiofrequency ablation of uterine leiomyomas. (Reprinted with permission from Gyn Surgical Solutions/Hologic, Inc.)
Transcervical RFA (Sonata System)
The Sonata system enables sonography-guided RFA of uterine fibroids using an incisionless, transcervical approach ([Fig. 2]). With the patient placed in dorsal lithotomy position, the cervix is serially dilated to 27 Fr to ultimately accommodate the 8.4-mm diameter assembled device. The device, consisting of a reusable curvilinear intrauterine ultrasound probe and a single-use RFA handpiece that combines into a single unit, is then inserted transcervically. The RFA handpiece comes equipped with a port for infusing hypotonic fluid into the endometrial cavity as needed. The device is advanced to the fundus and a survey is performed to identify the size and location of fibroids. Once the desired ablation zone of a particular fibroid has been determined, the tip of the ultrasound probe is articulated to target the fibroid and a sharp cannula is deployed from the shaft of the RFA handpiece, penetrating the fibroid tissue and stabilizing the device. The needle electrodes are then deployed. Once safety has been confirmed, the device is held steady, and the footswitch is pressed to deliver radiofrequency energy. Once the ablation is complete, the RF generator will automatically turn off. The needle electrodes and introducer can be retracted, and subsequent ablation can then be performed on the same fibroid or additional fibroids targeted in the same manner.[19] Patients return home the same day and require only NSAIDs for pain management.
Fig. 2 Transcervical radiofrequency ablation with the Sonata system (a-d), demonstrating the SMART Guide which delineates the ablation zone (red ellipsoid) (b, c) and thermal safety border (green ellipsoid) (c). (Reprinted with permission from Lindner LH, Roy K, Toub DB. Transcervical fibroid ablation (TFA) with the Sonata system: updated review of a new paradigm for myoma treatment. Current Obstetrics and Gynecology Reports 2022;11(3):238–248)
Multiple Treatment Options: When to Use One Approach Over Another?
Multiple Treatment Options: When to Use One Approach Over Another?
Current management strategies mainly involve surgical interventions, but the choice of treatment is guided by patient's age, medical and surgical history, and desire to preserve fertility. The management of fibroids also depends on the number, size, and location of fibroids.
RFA reduces the size of fibroids but does not eliminate them. Its minimally invasive nature, using heat to target fibroids one by one, thus reducing their size significantly, is ideal in improving symptom management and overall quality of life. Recovery is rapid and patients have reported only mild postoperative pain. Post-RFA pregnancy data are currently limited. We recommend RFA in patients with symptomatic FIGO type 2 to 6 myomas who do not desire future fertility.
Laparoscopic hysterectomy is a definitive therapy for fibroids with the lowest reintervention rates and the highest rate of symptom relief. It has a range outside of completely curing fibroids; the removal of fallopian tubes has been shown to reduce the risk of ovarian cancer; the removal of ovaries may be recommended for patients who have a family history of ovarian cancer or who test positive for BRCA-1, BRCA-2 gene mutations; and other pathologies such as endometriosis may be addressed concomitantly. We recommend hysterectomy in these situations and when women do not desire future fertility or prefer uterine preservation.
Laparoscopic myomectomy is perceived by many gynecologists to be a more technically complex procedure, but the advantages are real: less severe postoperative morbidity, faster recovery with laparoscopic procedures, and no significant difference between reproductive outcomes after laparoscopic or abdominal myomectomy. However, there have been reports of uterine rupture after laparoscopic myomectomy, thus emphasizing the importance of adequate closure of the myometrial defect. Additionally, perioperative complication rates can be as high as 30% particularly due to increased blood loss.[20] Less than 15% of patients who undergo myomectomy will require a second surgery at 5 years.[7] We recommend laparoscopic myomectomy as the intervention of choice for all fibroids not amenable to medical therapy or hysteroscopic resection in patients who desire future fertility.
UAE is a minimally invasive alternative to hysterectomy or myomectomy, and 85% of women experience improvement in heavy menstrual bleeding, pain, and symptoms related to uterus enlargement.[7] The procedure is especially effective for multiple fibroids and large fibroids. Global uterine size is affected by UAE, while RFA reduces individual fibroid volume only. In addition to its minimally invasive nature, it presents as an alternative to hormone therapy, involves minimal or no hospital stay, allows a quick return to daily activities, and significantly improved quality of life. It is important to note that for patients who desire future fertility, the fertility rates post-UAE have not yet been effectively quantified. We recommend UAE for patients who are symptomatic from their fibroids, do not desire future fertility, and wish to avoid surgery such as a hysterectomy.
Short- and Long-Term Outcomes
Short- and Long-Term Outcomes
Laparoscopic RFA
Laparoscopic RFA was first studied in fibroids with < 7 cm and less than 14-week-size uterus, but subsequent studies have demonstrated its use in fibroids up to 10 cm.[21]
[22] Though total adverse events are low (1.78%), a case report of postoperative necrosis and peritonitis in a treated fibroid of > 10 cm dimension has been described.[23] Serosal bowel injury and postoperative pelvic abscess due to ultrasound probe use were also noted in the pivotal HALT trial. The average length of stay is 10.7 hours with mean return to work after 4.3 days.[24]
In the pivotal HALT trial, menstrual blood loss reduction was measured via alkaline hematin.[23] This reduced within 3 months of treatment by 31.8% (95% confidence interval [CI]: −40.3% to −20.3%) and decreased to 38.3% (95% CI: −45.2% to −31.4%) at 12 months (p < 0.001). Similarly, within 3 months, the total mean fibroid volume reduced by 39.8% (95% CI: −44% to −35.6%) with continued decrease at 12 months to 45.1% (95% CI: −51.6% to −38.6%, p = 0.001). Decreased symptom severity and increased quality-of-life measures were also noted. Three-year follow-up has shown stable improvement in these two scores. Surgical reintervention rate at 1 year is low at 3.8% but has been reported as high as 11% at 3 years in the HALT follow-up survey.[25] Further evaluation noted that half of the subjects who underwent reoperation at 36 months were diagnosed with concurrent adenomyosis. This of note was an exclusion criterion to receiving RFA in the HALT trial and may account for the need for additional treatment. A meta-analysis of seven studies has shown the overall reintervention rate to be 4.39% (95% CI: 1.6–8.45%; I
2 = 65%).[26] For comparison, the rate of reintervention over the same period of time is 17% for UAE, 21% for hysteroscopic myomectomy, 24% for endometrial ablation, and 11% for laparoscopic myomectomy.[27]
Transcervical RFA
Transcervical myoma ablation is quick as well as incisionless. The average length of stay is 2.5 hours with over 50% of patients resuming normal activities after 1 day.[28] Transcervical RFA is designed for ablation of not only FIGO type 1 or 2 fibroids but also FIGO types 3, 4, 5, 6, and 2–5. Given the most frequent postprocedure effect is leiomyoma sloughing (in up to 30% of cases), this approach is not recommended for type 0 fibroids.
In the pivotal SONATA trial, the average reduction in total myoma volume was 62.4% (n = 128) by 12 months.[28] Menstrual bleeding reduction was defined as a 50% or greater reduction in a menstrual pictogram score in at least 45% of patients; this was achieved in 65.3% (79/121) of patients at 12 months posttreatment. Analysis of the U.S.-only cohort (n = 122) from the SONATA trial found 86.3% of patients experienced improved menstrual bleeding as soon as 3 months.[29] Only one patient underwent elective hysterectomy for abnormal uterine bleeding prior to 12 months, but hypermenorrhea can occur postablation. Similar findings regarding decrease in fibroid volume were found in the FAST-EU trial. A clinically meaningful reduction in menstrual blood loss was defined as a 22% reduction in bleeding. This occurred in 37 of 49 (75%) patients by 3 months. Of note, a majority of the fibroids treated in this cohort were type 1 or type 2 in location while the Sonata pivotal trial treated mostly type 3, 4, 5, or 6 fibroids.
Long-term studies have yielded promising results for transcervical RFA. Surgical reintervention rates due to heavy menstrual bleeding remain as low as 9.2% at 3 years and 11.8% at 5.4 years.[30] Quality of life and symptom severity scores remain stable at least until 3 years after treatment with 94% patients reporting continued satisfaction with transcervical RFA.[31] No long-term serious complications related to the device or procedure have been described.
Comparative Outcomes
Myomectomy is the second most common surgical treatment of fibroids.[32] Only two randomized studies have evaluated the performance of laparoscopic RFA compared to laparoscopic myomectomy given the unique similarities as less invasive procedures with quick recovery ([Table 1]). In TRUST (Trial of Uterine-Sparing Techniques) and a subsequent 1-year follow-up survey, both procedures led to significant improvement in fibroid-related symptoms such as heavy bleeding, increased abdominal girth, and pelvic pain. Laparoscopic myomectomy resulted in a greater reduction in symptom severity (12.1 vs. 23.4%, p < 0.05) and improvement in quality-of-life scores (95.6 vs. 78.7%, p < 0.05).[22] At 12 months, less patients who underwent laparoscopic myomectomy reported heavy menstrual bleeding. Contrarily, Brucker et al noted no differences in patient-reported outcomes between the two groups.[33]
[34] Both trials found decreased operative time, intraoperative blood loss, length of stay, and complication rates in laparoscopic RFA. Interestingly, despite use of intraoperative laparoscopic ultrasound, the total number of fibroids treated by laparoscopic RFA may be higher than laparoscopic myomectomy.[33] This is likely due to the fact that 1- to 2-cm fibroids can be easily accessed and ablated without the need of a myometrial incision.
Table 1
Comparison of surgical uterine-sparing interventions for uterine leiomyomas
|
Intervention
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Ideal leiomyoma characteristics
|
Approach
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Notable side effects or risks
|
Leiomyoma volume reduction at 12 mo (%)
|
UFS-QOL
HRQL score increase
|
Reintervention rate at 36 mo
|
|
L-RFA
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FIGO 2–6, < 7–10 cm
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Laparoscopic 10 mm + 5 mm incisions, percutaneous puncture
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Pelvic infection (rare)
|
45.1
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38.6 (36 mo)
|
11.0
|
|
TC-RFA
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FIGO 1–6, <7–10 cm
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Cervical dilation
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Leiomyoma sloughing, leukorrhea
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62.4
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43.7 (36 mo)
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8.2
|
|
Myomectomy
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FIGO 0–7, any size
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Hysteroscopic, laparoscopic, minilaparotomy, or abdominal
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Blood loss, greater LOS, surgical complications
|
100
|
(24 mo)
|
11.0
|
Abbreviations: FIGO, International Federation of Gynecology and Obstetrics; LOS, length of stay; L-RFA, laparoscopic radiofrequency ablation; TC-RFA, transcervical radiofrequency ablation; UFS-QOL HRQL, Uterine Fibroid Symptom and Quality of Life, Health-Related Quality of Life.
Source: Reprinted with permission from Stewart KA, Greenberg JA, Kho KA, Cohen Rassier SL. Radiofrequency ablation of leiomyomas. Obstet Gynecol 2023 (publish ahead of print). doi: 10.1097/aog.0000000000005196.
There are no studies that exclusively evaluate transcervical RFA and laparoscopic myomectomy. A comparative study (CHOICES) of all routes of myomectomy and transcervical RFA showed higher procedure and hospitalization costs in myomectomy ($7,563 vs. $11,425, p < 0.002).[35] Operative time and length of stay were shorter with transcervical RFA. The only complications reported were in three myomectomy patients who required perioperative transfusion.
Fertility Outcomes
Fibroids can cause infertility and adversely affect pregnancy including causing spontaneous abortion, malpresentation, preterm labor, Cesarean delivery, and postpartum hemorrhage.[36] RFA is not approved by the FDA for women who desire future fertility. This is in part due to initial clinical trials excluding premenopausal women who sought childbearing. In one case series of 30 pregnancies following laparoscopic RFA, there were 26 full-term live births (86.7%) and 4 spontaneous abortions (13.3%).[37] This miscarriage rate is similar to the U.S. national average. There was an equal distribution of cesarean and vaginal deliveries (50% each) with the leading indication for cesarean delivery the unknown safety of vaginal delivery following a RFA procedure. No adverse outcomes such as preterm delivery, placental abruption, or placenta accreta spectrum occurred, but one case of placenta previa and postpartum hemorrhage was reported. Though uterine rupture was not recorded, this is a rare event and notably only a 1.7% risk after myomectomy.[38] These overall findings are similar in studies examining transcervical RFA.[39] Further long-term data are needed to assess these less common but serious pregnancy-related risks to guide counseling patients who desire fertility and RFA. Preliminary data suggest childbearing may be safe and a full-term vaginal delivery can be a reasonable expectation.
RFA appears to have less long-term fertility consequences compared to myomectomy. Postablation MRI has shown no reduction in uterine wall thickness or development of myometrial scar.[40] This is an important finding as vaginal delivery may be contraindicated in some patients who undergo laparoscopic or abdominal myomectomy due to risk of uterine dehiscence and rupture. Likewise, postmyomectomy intrauterine adhesion formation can be as prevalent as 45%, but synechiae have not been seen after RFA during hysteroscopic evaluation.[41]
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[43] For women who wish to preserve fertility but are not good candidates for myomectomy, RFA and UAE are both viable options. The patient should be counseled about the limited fertility data for both options.
Conclusion
The safety and efficacy of RFA for symptomatic uterine fibroids is promising and rapidly emerging. Long-term studies have yielded promising results for both laparoscopic and transcervical RFA with low surgical reintervention rates and improved quality of life and symptom severity scores. As reproductive outcomes following RFA are not yet clearly known, further long-term data are needed to assess these less common but serious pregnancy-related risks to guide counseling patients who desire fertility and RFA.
