• Image-guided transcervical, transvaginal, and laparoscopic radiofrequency ablation (RFA) techniques heat tissue to the point of coagulation necrosis which typically leads to volumetric reduction of the targeted leiomyoma.
• In practice, FIGO type 2, 3 and most type 4 fibroids are easily accessed and treated with transvaginal (TC-RFA) or transcervical(TC- RFA) ablation. Those not safely accessible with transvaginal or transcervical techniques, which applies to many Type 4 and most Type 5 and 6 fibroids, are easily accessed with Laparoscopic RFA (LC-RFA). 
• RFA ablation has been shown to improve in symptoms in those heavy menstrual bleeding (AUB-L) and has a high satisfaction rate there is a measureable rate of subsequent surgery.
• Depending on the route of RFA, serious adverse events occur in 1.4 - 3.7 % of patients.
• While fertility and successful pregnancies have been reported with each of the RFA devices, the role of these techniques for those with infertility or otherwise desiring future pregnancy has not been established. 
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Background

Transcervical, transvaginal and laparoscopic radiofrequency ablation (RFA) employ electrical energy targeted with ultrasound to induce coagulation necrosis of leiomyoma tissue. Understanding the basics of RF energy, particularly as they apply to volumetric ablation is critical to optimizing both efficacy and safety. 

Radiofrequency electricity refers to current produced by alternating polarity in the RF range, between 300 kHz and 3 MHz); however, for most medical applications a frequency between 300 and 500 kHz  is typically used (lee et al). It is important to understand that in an alternating polarity current (typically called AC) there is no net directionality of ions in the circuit, so the concept of a “return” electrode doesn’t apply. Consequently, it should be conceptualized that the RF energy passes oscillates in tissue that exists between two electrodes.

Bipolar instruments have both electrodes in the device itself, such as a grasping forceps, while monopolar systems comprise two separate devices, one an electrode designed to focus RF energy at a point in the circuit, the tissue target - the “active” electrode, while the other has a large surface area designed to disperse the energy and positioned on the patient, remote from the surgical site – the “dispersive” electrode. The RF energy is developed by the RF generator, sometimes called the electrosurgical unit (ESU), that converts the typical 50-60 Hz wall output to the RF frequency waveform. The high frequency, relatively low voltage alternating current produced by the ESU is focused by the active electrode(s) causes oscillation of intracellular ions, including proteins, that results in frictionally induced heat that causes instant cell death at temperatures above 60º C with coexisting tissue desiccation and protein denaturation via the breakage of hydrothermal bonds. For monopolar systems, the dispersive electrode disperses the current, thereby preventing tissue injury. When the intracellular tissue rapidly achieves a temperature of 100˚ C, the intracellular water undergoes a liquid-gas conversion, volumetric expansion, and resulting cellular and tissue vaporization. This process is employed for RF tissue cutting. 

Radiofrequency systems designed for leiomyoma ablation are typically monopolar comprising the ESU, a sharp-tipped probe typically equipped at the distal end with a deployable single or multi-tined electrode array (the “active” electrode), generally two large dispersive electrodes and the cables connecting these elements. After “mapping” the leiomyoma using an ultrasound transducer, the probe is directed towards and into the target tissue where the electrode or electrode array is deployed taking care to avoid critical anatomic structures such as bowel, bladder, ureter, and major blood vessels. The operator activates the generator holding the active electrode in place, with the duration of activation generally determined by one or a combination of termperature and tissue impedance based on feedback from sensors located in the electrode itself.  The shape and volume of ablation depend on a number of variables including the temperature reached, the time at that temperature, and the shape, number, and length of the electrode tines, and the tissue impedance that depends on inate features, the vascular perfusion, and the general water content (Lee et al).  The relatively high Wattage, and, consequently, high current, required for volumetric ablation requires a large surface area for the dispersive electrode to prevent thermal damage to underlying skin, a circumstance that generally requires the use of two such electrodes. Some systems actually have thermocouples (temperature sensors) built into their dispersive electrodes to act as a safety mechanism to prevent skin damage should temperature reach a predetermined level, at which time the machine automatically switches off. 

Types/Approaches for RFA of Leiomyomas

 There are three main approaches to RFA: transvaginal  (TV-RFA), transcervical  (TC-RFA) and laparoscopic RFA (L-RFA). 

 Transvaginal RF Ablation (TV-RFA)

 The STARmed© fibroid radiofrequency ablation was FDA approved in 2018 for the treatment of fibroids using real time transvaginal ultrasound in combination with a vaginally inserted radiofrequency needle electrode as seen in Figure 1B. The ultrasound device with the probe guider attachment is placed into the vagina. Leiomyomas are then mapped. Once mapping is complete and the location of each fibroid is confirmed, the active tip of the radiofrequency needle is adjusted between 5 mm and 30 mm based on the size of the fibroid. The radiofrequency needle can be introduced either transcervically or through the anterior or posterior fornix under ultrasound guidance. After centralization of the needle into a specific myoma, ablation can be performed as seen in Video Animation 1. The radiofrequency generator operates at 480 kHz with a maximum power of 200 W at a temperature ranging from 5˚ C to 95˚ C. This system uses a coolant circulation system of the electrode to maintain suitable impedance at the surface as seen in Figure 1A. A single needle ablation pulse achieves a necrosis volume of approximately 1 cm³ after 5-10 seconds. The core of the target myoma is found to be ablated once the echo-enhanced area on ultrasound reaches 80-90% of the myoma. Contrast enhanced ultrasound can additionally be used to confirm the absence of vascularization. At this time more myomas can be ablated or the needle electrode is removed. 

Transcervical RF Ablation (TC-RFA)

 The Sonata© system was FDA approved in 2020 and it uses a combination of radiofrequency ablation and ultrasound guidance in one single handpiece to treat fibroids without abdominal incisions. This system also uses approximately 60 cc of hypotonic fluid to reduce the risk of unintended RF energy dispersion. After the cervix is serially dilated to 27 French, an 8.75 mm handpiece containing the ultrasound (as seen in Figure 2) and ablation device is inserted through the cervix. The physician then uses the ultrasound to survey the uterus to map leiomyomas. Once fibroid is identified and determined to be accessible for ablation, the SMART (Setting Margins of Ablation in Real Time) Control is used to adjust the depth and size of the ablation zone. The ablation zone is a red ellipse and the thermal safety border a green ellipse in Video Animation 3. The minimum size of the ablation zone is 2.0 x 1.3 cm, and the maximum size is 4.9 x 4.2 cm. The ablation zone is aligned and sized using the graphical overlay targeting guide over the live image. Once the size and location of the ablation zone are determined to be safe for ablation, the trocar tip introducer is advanced into the fibroid. A safety rotation is then performed to ensure the green thermal safety border is within the serosal boundary of the uterus in all adjacent visual planes. Once safety margin is confirmed, the needle electrode is deployed. After a second safety rotation is completed with the live image ultrasound and graphical overlay targeting guide, delivery of the radiofrequency energy is initiated using the foot switch control. The length of time for energy delivery is based on the size of the desired ablation. Depending on the size of the ablation, RF energy delivery times range from 1 to 7 minutes. The target temperature during ablation is 105° C. Following the radiofrequency ablation cycle, the radiofrequency generator automatically turns off and the needle electrodes and introducer are retracted. The treated fibroids on ultrasound will take on a lighter appearance due to the presence of gas from elevated temperatures. Subsequent ablations can be performed as needed. 

 Laparoscopic RF Ablation (L-RFA)

 The Acessa ProVu© system was FDA approved in 2012 for the treatment of fibroids and it uses a combination of laparoscopy and ultrasound guidance to treat fibroids as seen in Video Animation 3. This system uses a 5 mm laparoscope, a 10 or 12 mm reusable laparoscopic ultrasound probe and a 3.4 mm radiofrequency ablation handpiece with a deployable seven needle electrode array as seen in Figure 3B and 3C.The Acessa ProVu© guidance system allows real time visualization of the ultrasound transducer and the hand piece. Once the myomatous uterus is mapped the RFA handpiece is inserted percutaneously under laparoscopic guidance and advanced into the target fibroid under ultrasound guidance. Care should be taken to identify the inferior epigastric arteries prior to insertion of the handpiece and as piercing the epigastric vessels can lead to a hematoma. Depending on the size and shape of the fibroid, the electrode array is deployed according to a proprietary treatment algorithm. After verifying the correct position of the array within the fibroid capsule with the ultrasound transducer and safety of other visceral structures in proximity to the handpiece the surgeon initiates the ablative treatment. The radiofrequency generator operates at 460 kHz with a maximum power of 200 W at a temperature of 15˚ C to 125˚ C. Current is delivered to the electrode tip and array (if the latter was deployed), permitting ablation of the targeted and localized fibroid tissue. Ablation time can occur from 30 seconds to 12 minutes at a target temperature of 95˚C. After ablation has completed, the handpiece should be allowed to cool in the target tissue for at least 60 seconds prior to removing it from the tissue. After each ablation, the probe is withdrawn from the fibroid with concurrent coagulation of the probe track. Hemostasis is confirmed visually after each ablation. Depending on the size and location of the fibroids, multiple fibroids can be ablated during one serosal puncture. After completion of the ablative treatment, the trocar fascial and skin sites are closed according to the surgeon’s standard surgical practice.

Outcomes of RF Ablation

There is a growing body of evidence demonstrating the efficacy of image guided RF ablation of leiomyomas. This needs to be added

Patient Counseling and Consent Consderations

Patient Selection Consderations

Operating / Procedure Room Setup

Procedure Descriptions