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Global Endometrial Ablation Devices: Minimally Invasive Surgical Alternatives to Hysterectomy

Arleen H. Song, MD, MPH

In the search for alternatives to hysterectomy in women with abnormal uterine bleeding (AUB), the introduction of hysteroscopic endometrial ablation some 25 years ago was hailed as a major step forward. Since then, even safer and more effective devices have been introduced to make this procedure accessible to an ever-growing spectrum of women with menorrhagia.

Abnormal uterine bleeding affects approximately 20% to 25% of healthy, premenopausal wo-men, accounting for 33% of referrals to gynecologic practices and up to 25% of the hysterectomies performed each year. Menorrhagia is generally defined as menstrual bleeding lasting longer than 7 days or menstrual blood loss greater than 80 mL.1

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FIRST-GENERATION TECHNIQUES


Traditionally, hysterectomy has been the surgical procedure of choice for excessive uterine bleeding refractory to medical management but a number of alternatives exist today. In an attempt to provide such an alternative DeCherney and Polan2 introduced endometrial ablation—ie, elimination of the endometrium by thermal energy or resection—in the early 1980s, describing the use of a urologic loop electrode to treat women with menometrorrhagia. Rollerball ablation was first introduced in Japan in 1988, and in the United States in 1989.3,4 This became the most common hysteroscopic ablation technique because of its ease of use and decreased risk of complications.

Endometrial ablation was further improved in 1990, when a continuous-flow resectoscope and low-viscosity distension medium were used to perform transcervical resection of the endometrium. In this technique, the cervix is dilated to about 9 mm to accommodate the hysteroscope, and the uterus is distended. A loop electrode, roller electrode, or laser is then applied to destroy the endometrium. This technique comprised the first generation of endometrial ablations with a review confirming that compared with hysterectomy, endometrial ablation is a reasonable alternative with high rates of satisfaction and efficacy.5 However, first-generation hysteroscopic endometrial ablation required a high level of surgical skill, with risks of uterine perforation, cervical laceration, and intraoperative fluid overload leading to electrolyte abnormalities.

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SECOND-GENERATION DEVICES

To overcome these limitations second-generation endometrial ablation devices were introduced in the 1990s. These global devices were developed to provide a simpler procedure with less risk but the same efficacy as traditional hysteroscopic endometrial ablation. To date, five global endometrial ablation devices have been approved by the US Food and Drug Administration (FDA) (Table 1). These devices have been compared with traditional hysteroscopic rollerball ablation in randomized, controlled trials, and were found to be as efficacious as traditional ablation with an improved safety profile.

Table not available online

TABLE 1. Comparison of Second-generation Endometrial Ablation Devices

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PATIENT SELECTION

tion are women with AUB refractory to medical management. A thorough medical history must be obtained, including bleeding patterns, comorbidities, and medications; and a complete physical examination performed. The workup should exclude pregnancy, pelvic infection, cervical or vulvar neoplasia, and systemic or iatrogenic etiologies for abnormal bleeding. An endometrial biopsy should be obtained in all cases to document absence of endometrial hyperplasia or neoplasm. Diagnostic hysteroscopy or saline-infusion ultrasonography may be indicated to exclude submucosal fibroids or polyps as the cause of bleeding. These diagnostic studies will also confirm that the endometrial cavity is appropriate for ablation. In general, the uterine cavity should be less than 10 cm to 12 cm in length and free of intrauterine pathology such as fibroids and polyps. However, several of the second-generation ablation devices can accommodate some variations in the uterine cavity. Contraindications to endometrial ablation are listed in Table 2.

Table not available online

TABLE 2. Contraindications to Endometrial Ablation

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CURRENT OPTIONS

ThermaChoice I, II, III

In 1997, the ThermaChoice uterine balloon therapy (UBT) system became the first global endometrial ablation device approved by the FDA. This method relies on a balloon that is filled with a 5% dextrose solution, utilizing heat and pressure within the uterine cavity to perform ablation. The balloon is designed to provide coverage of the entire cavity. This device requires minimal cervical dilation but does require pretreatment of the endometrial lining with either a gonadotropin-releasing hormone agonist or dilation and curettage. After priming the system and deflating the balloon to -180 mm Hg, a catheter is inserted into the uterine cavity and inflated to a pressure of 180 mm Hg. The fluid is then heated to 87°C for a total treatment time of 8 minutes. Subsequent to the introduction of the UBT system, the impeller has been improved to circulate fluid within the balloon and the silicone balloon was modified in 2004 to provide better coverage and expansion within the uterine cavity.

Because it was the first second-generation endometrial ablation device approved by the FDA, there has been more experience with the UBT system in the United States than with comparable devices. In a multicenter, randomized trial of the UBT system versus rollerball ablation in 1996, women were pretreated with dilation and curettage at the time of ablation. Follow-up was reported at 1-, 2-, 3-, and 5-year intervals. One-year data showed comparable eumenorrhea rates (UBT, 80.2%; rollerball, 84.3%). However, amenorrhea rates at 1 year for UBT and rollerball were 15.2% and 27.2%, respectively. Both methods resulted in high satisfaction rates.6 At 5-year follow-up, the UBT group and rollerball group reported 95% and 97% rates of amenorrhea or eumenorrhea, respectively.7

Her Option Uterine Cryoablation

The Her Option uterine cryoablation device is a software-controlled device that generates extremely cold temperatures. Pretreatment of the endometrial lining was performed in the pivotal FDA trial. A 5-mm probe is inserted into the uterine cavity and the compressor system drives the unit as a coolant is recirculated and replenished through the system. This generates an –ice ball” with temperatures ranging from -100çC to -120çC. The ice ball is followed by transabdominal ultrasonography, and the procedure is terminated when ablation reaches the uterine serosa. Tissue necrosis lags approximately 3 mm to 4 mm behind the ice ball, and occurs at -15çC to -20çC.8 This procedure takes from 10 to 20 minutes to complete.

Duleba et al9 published the initial prospective, randomized, controlled trial comparing cryoablation versus rollerball in 2003. This trial included 279 women with menorrhagia. Patients with uterine cavities larger than 10 cm were excluded. All patients were pretreated with intramuscular (IM) leuprolide acetate 3.75 mg. Follow-up was performed at 1- and 2-year intervals. Cryoablation and rollerball amenorrhea rates were 27.6% and 55.6%, respectively. At 2 years, 94% of subjects reported no abnormal bleeding with cryoablation, and 92% reported no abnormal bleeding with rollerball ablation.9

HydroThermAblator

The HydroThermAblator (HTA) system was approved by the FDA in 2001. This device utilizes a closed-loop system to deliver heated 0.9% saline solution under direct hysteroscopic guidance. The endometrium is pretreated prior to ablation. The cervix must be dilated to approximately 8 mm to accommodate the hysteroscope and sheath. The heated saline solution comes into direct contact with the endometrium, ablating it to the innermost layer in 10 minutes.

There was a multicenter, prospective, randomized, controlled trial for FDA approval comparing the HTA system with rollerball ablation. All patients were pretreated with one dose of leuprolide acetate 7.5 mg IM. At 1 and 3 yearsê follow-up amenorrhea rates were comparable for the HTA and rollerball ablation (40% and 53% for HTA; 51% and 46% for rollerball ablation).10

NovaSure

Approved by the FDA in September 2001, the NovaSure device is an impedance-controlled endometrial ablation system. It utilizes bipolar radiofrequency (RF) energy to desiccate and evacuate the endometrial tissue. The endometrium does not require pretreatment. During the procedure the cervix is dilated to 8 mm to allow for a sheath containing a bipolar array that expands within the uterine cavity. After a cavity check confirms uterine-wall integrity, bipolar RF energy is delivered to the endometrium. The amount of energy required is calculated based on the cavity length and width. The average treatment time is 90 seconds.

In the trial for FDA approval, Cooper et al11 compared the NovaSure endometrial ablation system with rollerball ablation. No pretreatment was used. At 1-year follow-up, 90.9% of NovaSure-treated patients and 87.8% of rollerball-treated patients reported eumenorrhea or amenorrhea. Average procedure time in the NovaSure group was 4.2 minutes, compared with 24.2 minutes in the rollerball group.11

A subsequent double-blind, randomized, controlled trial comparing NovaSure with ThermaChoice was performed by Bongers et al.12 The same provider performed all procedures. The authors reported significantly higher amenorrhea rates at 1 year in women who underwent NovaSure ablation (43% versus 8%). The authors also found a statistically significant difference in satisfaction rates in patients who received NovaSure versus ThermaChoice (90% versus 79%). It is important to note that the pretreatment protocol was not followed for patients in the ThermaChoice arm, and may have contributed to the lower amenorrhea and satisfaction rates.12

Microsulis Endometrial Ablation

The Microsulis microwave thermal ablation system was approved by the FDA in 2003. This technology consists of a control unit with a foot pedal and a reusable, hand-held device with an 8.5-mm probe. The cervix is dilated to 9 mm, and the probe is inserted to the level of the midfundus. The probe is activated by the foot switch, raising the temperature to between 70çC and 80çC. Microwave energy is generated by a magnetron and passed along the tip of the probe at a frequency of 9.2 GHz. Absorption of microwave energy generates heat that is conducted deeper into the tissue to destroy the basalis layer. Because the thermal penetration can reach approximately 5 mm to 6 mm, myometrial measurements should be determined beforehand to determine the risk of uterine serosal penetration. The probe is moved laterally to the bilateral cornua in a sweeping motion throughout the cavity. Treatment time is approximately 3 to 4 minutes. This device is approved for cavity measurements up to 14 cm and fibroid-associated distortions of less than 3 cm.

The Microsulis system has shown excellent outcomes. In the FDA pivotal trial, all patients were pretreated with depot leuprolide acetate 3 to 5 weeks prior to the procedure. Women with uterine cavities up to 14 cm were included, and approximately 22% of patients in the study had fibroids of less than 3 cm. Amenorrhea rates for the microwave and rollerball arms were 61.3% and 51%, respectively. Overall success rates for microwave versus rollerball ablation were 96.2% and 92.7%, respectively. The amenorrhea rate for patients with fibroids in the microwave arm was 61.3% compared with 38.5% in the rollerball arm.13

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CONCLUSION

It is clear that second-generation endometrial ablation devices demonstrate efficacy rates that parallel traditional, first-generation hysteroscopic endometrial ablation, as supported by level 1 evidence. In addition, these devices have also been shown to have an improved safety profile when compared with traditional hysteroscopic endometrial ablation. The ease of use, efficacy, and safety profiles have also made these devices feasible for use in the office setting for appropriate candidates. In addition, each device provides different features that accommodate different uterine cavity types. This development in surgical technology has given gynecologists and patients a minimally invasive surgical option to hysterectomy.

Arleen H. Song, MD, MPH, is assistant professor, Division of Minimally Invasive Surgery, Department of Obstetrics and Gynecology, University of Michigan Medical Center, Ann Arbor.

References

1. Carlson KJ, Nichols DH, Schiff I. Indications for hysterectomy. N Engl J Med. 1993;328(12):856-860.
2. DeCherney A, Polan ML. Hysteroscopic management of intrauterine lesions and intractable uterine bleeding. Obstet Gynecol. 1983;61(3):392-397.
3. Lin BL, Miyamoto N, Tomomatsu M, Horikoshi H, Nakamura H, Iwata Y. The development of a new hysteroscopic resectoscope and its clinical applications on transcervical resection (TCR) and endometrial ablation (EA) [in Japanese]. Jpn J Gynecol Obstet Endosc. 1988;4:56-61.
4. Vancaillie TG. Electrocoagulation of the endometrium with the ball-end resectoscope. Obstet Gynecol. 1989;74(3 pt 1):425-427. 388-392.
5. Lethaby A, Shepperd S, Cooke I, Farquhar C. Endometrial resection and ablation versus hysterectomy for heavy menstrual bleeding. Cochrane Database Syst Rev. 2000;(2):CD000329.
6. Meyer WR, Walsh BW, Grainger DA, Peacock LM, Loffer FD, Steege JF. Thermal balloon and rollerball ablation to treat menorrhagia: a multicenter comparison. Obstet Gynecol. 1998;92(1):98-103.
7. Loffer FD, Grainger D. Five-year follow-up of patients participating in a randomized trial of uterine balloon therapy versus rollerball ablation for treatment of menorrhagia. J Am Assoc Gynecol Laparosc. 2002;9(4):429-435.
8. Smith JJ, Fraser J. An estimation of tissue damage and thermal history in the cryolesion. Cryobiology. 1974;11(2):139-147.
9. Duleba AJ, Heppard MC, Soderstrom RM, Townsend DE. A randomized study comparing endometrial cryoablation and rollerball electroablation for treatment of dysfunctional uterine bleeding. J Am Assoc Gynecol Laparosc. 2003;10(1):17-26.
10. Corson SL. A multicenter evaluation of endometrial ablation by Hydro ThermAblator and rollerball for treatment of menorrhagia. J Am Assoc Gynecol Laparosc. 2001;8(3): 359-367.
11. Cooper J, Gimpelson R, Laberge P, et al. A randomized, multicenter trial of safety and efficacy of the NovaSure system in the treatment of menorrhagia. J Am Assoc Gynecol Laparosc. 2002;9(4):418-428.
12. Bongers MY, Bourdrez P, Mol BW, Heintz AP, Brolmann HA. Randomised controlled trial of bipolar radio-frequency endometrial ablation and balloon endometrial ablation. BJOG. 2004;111(10): 1095-1102.
13. Cooper JM, Anderson TL, Fortin CA, Jack SA, Plentl MB. Microwave endometrial ablation vs. rollerball electroablation for menorrhagia: a multicenter randomized trial. J Am Assoc Gynecol Laparosc. 2004;11(3):394-403.

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