Courtesy Gynesonics
Coupling of the Sonata RFA handpiece and IUUS probe
Initially, the IUUS probe enables identification of fibroids from within the uterine cavity, then guides deployment of an introducer and needle electrode into the targeted fibroid(s). The probe image is curvilinear, penetrates more than 9 cm, and provides a 90-degree field of view.
The RFA handpiece contains the introducer and needle electrode array. It snaps together with the IUUS probe to form and integrate into a single treatment device that contains all controls needed to place and size the ablation. Mechanical stops and lockouts within the RFA handpiece further enhance proper localization and sizing of the ablation.
The system’s graphical guidance software, also known as the SMART Guide, is a real-time graphical overlay on the ultrasound display, which enables one to visually select deployment length, width, and position of the ablation guides. In so doing, the mechanical stops for the introducer and needle electrodes are determined prior to their insertion into the targeted fibroid(s). This was validated in more than 4,000 ablations in bovine muscle and human-extirpated uteri, as well as in vivo at time of laparotomy.
By displaying the ellipsoidal region where the ablation will take place (ablation zone) along with a surrounding ellipsoid (thermal safety border) where tissue temperature will be elevated, the SMART Guide provides a safer and more accurate understanding of the ablation than if it showed only the ablation zone.
Courtesy Gynesonics
Coupling completed
As with transabdominal or transvaginal sonography, the serosa will appear hyperechoic at the time of intrauterine ultrasound. By using the SMART Guide, the ablation is sized and positioned to encompass as much of the fibroid as possible while maintaining thermal energy within the uterine serosal margin. Once the desired ablation size has been selected, and safe placement of the needle electrodes is confirmed by rotating the IUUS probe in multiple planes, therapeutic RF energy is delivered to the fibroid; the fixed treatment cycle is dependent on ablation size.
The system will modulate power (up to 150W) to keep temperature at the tips of the needle electrode at 105° C. Moreover, the time of energy delivery at the temperature of 105° – 2-7 minutes – is automatically set based on ablation size, which is a continuum up to 4 cm wide and up to 5 cm long. Multiple ablations may be utilized in a particularly large fibroid.
Unlike hysteroscopic myomectomy, only a small amount of hypotonic solution is instilled within the uterine cavity to enhance acoustic coupling. Furthermore, the treatment device (RFA handpiece and IUUS probe) is only 8.3 mm in diameter. This requires Hegar dilatation of the cervix to 9.
The procedure
After administering anesthesia (regional or sedation), dispersive electrode pads are placed on the anterior thighs. After the cervix is dilated to Hegar dilatation of 9, the treatment device is inserted transcervically into the uterine cavity and the fibroid(s) are identified with the ultrasound probe. The physician plans and optimizes the ablation by sizing and aligning the graphical overlay targeting guide (the SMART Guide) over the live image. Once the size and location of the ablation are set, the trocar-tipped introducer is advanced into the fibroid. After ensuring the guide is within the serosal boundary, the needle electrodes are deployed.