Endometrial ablation: Non-resectoscopic techniques

INTRODUCTION — The introduction of non-resectoscopic endometrial ablation (NREA) techniques has greatly increased the use of endometrial ablation as a therapeutic option for patients with abnormal uterine bleeding. NREA is performed with a device that is inserted into the uterine cavity and delivers energy to uniformly destroy the uterine lining. NREA techniques are also referred to as second generation ablation.

By contrast, resectoscopic endometrial ablation (REA) techniques are performed under hysteroscopic visualization, using resectoscopic instruments to ablate or resect the endometrium. NREA techniques are more widely practiced than REA, since they require less specialized training and have a shorter operative time [1].

NREA techniques will be reviewed here. Other related content is discussed separately and includes:

●General principles, including indications, contraindications, preoperative issues (eg, endometrial preparation), postoperative care, and complications of endometrial ablation, as well as how to choose between NREA and REA: (See "Overview of endometrial ablation".)

●Techniques for REA: (See "Endometrial ablation or resection: Resectoscopic techniques".)

●Alternate management options for abnormal uterine bleeding: (See "Abnormal uterine bleeding in nonpregnant reproductive-age patients: Management".)

NON-RESECTOSCOPIC ABLATION DEVICES — NREA technologies approved for use in the US by the Food and Drug Administration (FDA) are:

●Bipolar radiofrequency (NovaSure).

●Hot liquid-filled balloon (ThermaChoice; no longer available in the United States).

●Cryotherapy (Her Option [no longer available in the United States], Cerene).

●Circulating hot water (Hydro ThermAblator).

●Microwave (Microwave Endometrial Ablation [MEA]; no longer available in the United States).

●Combined thermal and bipolar radiofrequency (Minerva).

●Vapor ablation (Mara). This device was approved by the FDA in 2017 [2].

Two other brands of hot liquid-filled balloon devices are available outside of the United States: Cavaterm and Thermablate EAS.

ROLE OF HYSTEROSCOPY — Most NREA techniques do not require hysteroscopy, with the exception of the Hydro ThermAblator, during which hot water is instilled into the uterus through a hysteroscopic sheath. For other techniques, preoperative hysteroscopy is necessary only if the uterine cavity has not been assessed for leiomyomas or endometrial polyps in the preoperative period. Also, the manufacturer of the microwave ablation system advises hysteroscopic evaluation before and after ablation [3].

The endometrial cavity should be assessed preoperatively in all patients undergoing endometrial ablation. Performing this assessment of the uterus during the preoperative evaluation is optimal, since it helps to guide surgical planning (eg, preparing for myomectomy if a submucosal fibroid is present). If the uterine cavity has not been assessed preoperatively, a diagnostic hysteroscopy should be performed just prior to the ablation procedure. (See "Overview of endometrial ablation", section on 'Assessment of the uterus'.)

Postoperative hysteroscopy is potentially useful to identify areas of remaining endometrium or detect uterine perforation. Some surgeons ablate endometrial remnants using resectoscopic instruments. However, the clinical benefit of hysteroscopy for these indications is uncertain. There are no data regarding whether small amounts of residual endometrium following NREA impact treatment success; data suggest that partial REA is successful [4,5].

Evaluation of uterine perforation after blind transcervical procedures is usually performed only in selected patients in whom there is reason to suspect perforation (eg, an instrument was inserted past the depth of the uterine fundus). (See "Uterine perforation during gynecologic procedures", section on 'Diagnosis'.)

ABLATION METHODS — This section will review the energy sources and technical specifications for NREA devices. Uterine requirements and operative duration for each procedure are listed in the table (table 1). In general, endometrial destruction is achieved when the tissue is heated to 65°C or cooled to -60°C.

Bipolar radiofrequency — The bipolar radiofrequency device (NovaSure) is a three-dimensional bipolar mesh probe that delivers radiofrequency current (a type of electrical energy) until a specific tissue impedance is reached (figure 1A-B). The NovaSure generator applies up to 180 watts of power.

The device is inserted into the uterine cavity and the mesh is expanded until it is in contact with the endometrium. Suction is then applied to the endometrial cavity, thereby drawing the endometrium closer to the bipolar mesh probe. The suction also removes debris and vapor that can increase impedance and reduce the depth of energy penetration. The system will shut down when complete desiccation has occurred (calculated at a tissue impedance of 50 ohms of resistance) or after a total treatment time of two minutes. The average treatment time is just over one minute and the average depth of ablation is 4 to 5 millimeters.

The system also evaluates cavity integrity by emitting carbon dioxide and assessing for leaks. If the integrity check fails, the user will not be able to activate the ablation phase of the procedure.

Uterine requirements — Uterine cavity and cervical dilation parameters for NovaSure ablation are [6]:

●Diameter of the original NovaSure device is 8 mm, and the diameter of the NovaSure Advanced device is 6 mm.

●Sounded cavity length ≥6 to ≤10 cm; alternatively, ≥4 cm from internal cervical os to fundus.

●Cornua to cornua distance ≥2.5 cm.

●Patients with submucosal leiomyomas or with endometrial polyps >2 cm were excluded from the FDA approval studies.

●No irregularly shaped cavities.

Intraoperative predictors for failure of radiofrequency endometrial ablation were evaluated in a retrospective cohort study (1178 patients) [7]. Failure was defined as subsequent development of abnormal uterine bleeding, pelvic pain, or dysmenorrhea that necessitated surgical intervention or medical intervention. Predictors for ablation failure were uterine sounding length >10.5 cm (2.6-fold increased risk), uterine cavity length (from fundus to endocervix) >6 cm (twofold), uterine width >4.5 cm (twofold), uterine surface area (uterine cavity length multiplied by uterine width) >25 cm² (twofold), procedure duration <93 seconds (2.6-fold), and radiofrequency ablation index (procedure duration divided by the surface area) (3.1-fold).

Outcome — Studies in which patients who underwent NovaSure ablation were followed for five or more years reported high rates of reduced uterine bleeding (97 to 98 percent) and amenorrhea (75 to 97 percent) [8,9]. There were low rates of repeat ablation (1 to 4 percent) and hysterectomy (3 to 8 percent).

Advantages/disadvantages — NovaSure ablation does not require endometrial preparation, since it adjusts ablation depth by measuring tissue impedance. This may increase the ease of scheduling in comparison with other endometrial ablation techniques. (See "Overview of endometrial ablation", section on 'Endometrial preparation'.)

NovaSure was not evaluated in the FDA approval studies for use in patients with intracavitary fibroids. However, some data suggest that bipolar radiofrequency ablation is successful in this population. In a prospective series of 65 patients with endometrial polyps or fibroids up to 3 cm who underwent bipolar radiofrequency ablation, 95 percent had improvement in uterine bleeding at one-year follow-up [10].

Cryoablation — Cryoablation by Her Option is a technique in which a cryoprobe is inserted into the uterine cavity (figure 2A-B). The probe is cooled either by liquid nitrogen or by differential gas exchange. An elliptical ice ball approximately 3.5 by 5 centimeters forms around the probe when it is cooled to less than -90°C. At the edge of the ice ball, the tissue temperature is 0°C, which is nondestructive. A temperature of -20°C is lethal to tissue; this temperature is reached approximately 3 to 5 mm from the edge of the ice ball. Therefore, the endometrial tissue exposed to this low temperature, including the basalis layer of the endometrium (figure 3), is permanently destroyed. The number of ice balls that must be created to destroy the entire uterine cavity is dependent upon the size of the cavity. Intraoperative ultrasonography is used to monitor probe placement and depth of tissue freezing. In general, two to three ice balls are sufficient (figure 4). Each freeze cycle takes two to six minutes.

Cryoablation by the Cerene technique is performed using nitric oxide as a freezing agent. The cervix is dilated to insert the 6 mm device probe, and the uterus is sounded to determine the length of the uterine cavity. Prior to probe insertion, the exhaust hose is connected to the exhaust bag. The device is turned on and the probe is inserted up to the uterine fundus to ensure that the number on the probe correlates with the known size of the uterine cavity. The sheath retraction nob is turned until the LCD screen displays 2.5 cm. The cavity liner is deployed and safety checks are performed to detect any possible perforation. The sheath retraction knob is turned until the uterine cavity length is selected and final safety checks are performed; treatment is started for 2.5 minutes. After treatment, the vent lock is then unlocked to vent the remaining nitric oxide. The uterine cavity is allowed to thaw and the vacuum is initiated within the liner to expedite device removal.

Uterine requirements

●Uterine parameters for Her Option ablation (no longer available in the United States) are [11]:

•Diameter of device 5.5 mm.

•Sounded cavity length ≥4 to ≤10 cm.

•Patients with intramural leiomyomas ≤2 cm in diameter were included in the FDA approval studies; patients with pedunculated fibroids or endometrial polyps were excluded.

●Uterine parameters for Cerene are [12]:

•Cervix should be dilated to 6 mm.

•Sounded cavity length ≤10 cm (uterine cavity length: >2.5 but <6.5 cm).

•Patients with an endometrial polyp >1 cm in diameter, any submucous fibroids, or any intramural fibroids that distorted the uterine cavity were excluded in the FDA approval studies.

Outcome — A randomized trial compared Her Option with rollerball ablation in 279 patients [13,14]. There were few adverse events; major complications included, in the Her Option group, one patient who underwent a hysterectomy 43 days after the procedure for severe uterine bleeding and one patient who was treated with rollerball was hospitalized for hematometra. At two-year follow-up, patients in the Her Option group compared with the rollerball group had similar rates of either reduced uterine bleeding or amenorrhea (94 versus 92 percent). Rates of hysterectomy (7 and 8 percent) and repeat ablation (3 and 1 percent) were similar between groups.

The Cerene device was evaluated in a prospective, multicenter, single-arm study including 242 patients (mean age 40.1 years) undergoing treatment for heavy menstrual bleeding (HMB); there were no reported major adverse device effects or major adverse events [15]. The primary effectiveness endpoint (reduction of bleeding at 12 months) was achieved in 77 percent of patients and the majority (90 percent) of patients were satisfied or very satisfied with their outcome; outcome results were not available for eight patients. Four patients (1.7 percent) required further intervention (medical or surgical) for continued HMB.

Advantages/disadvantages — Use of cold destroys tissue and may also cause numbness. Therefore, cryoablation is potentially less painful than the other NREA techniques, which all use high temperatures. Less perioperative pain is an advantage for use with no anesthesia or with local anesthesia.

Another unique feature of cryoablation is the use of perioperative sonography. This serves as both an advantage and disadvantage. Cryoablation is not a totally blind procedure, which helps to ensure complete ablation and avoid complications. On the other hand, it can be difficult to visualize the ice ball if the patient is obese and the need for sonography adds to the expertise and/or personnel required to perform the procedure.

An advantage of the Cerene device is that while endometrial preparation may be used, the procedure also can be performed in the early proliferative phase of the menstrual cycle without endometrial preparation. Another advantage is the absence of postoperative intrauterine synechiae and the ability to evaluate the endometrium after treatment. In the prospective study described above (see 'Outcome' above), of the 223 patients who underwent hysteroscopy 12 months after their Cerene cryoablation procedure, complete evaluation of the uterine cavity was possible in 204 out of 220 (93 percent) patients; uterine cavity entry was not possible in three patients due to pain intolerance or cervical stenosis [15].

Circulating hot water (hydrothermal) — Hydrothermal ablation (Hydro ThermAblator [HTA]) refers to a technique in which a hysteroscope sheath is inserted into the uterine cavity under direct hysteroscopic visualization (figure 5). Heated isotonic saline is administered into the uterus through the sheath. To maintain a low uterine distension pressure (<70 mmHg), the fluid is instilled using gravity rather than a pump. The treatment phase lasts for 10 minutes, during which the fluid should be at a temperature of 90°C. An intrauterine cool down phase is then performed for one minute with the fluid at 45°C.

Safety apparatus within the equipment detects whether any fluid has escaped from the closed system, which will shut down if more than 10 cc of fluid are lost, whether through the cervix, fallopian tubes, or a uterine perforation.

Uterine requirements — Uterine cavity and cervical dilation parameters for HTA ablation are [16]:

●Diameter of device 7.8 mm.

●Sounded cavity length ≥6 to ≤10.5 cm.

●Patients with submucosal fibroids were excluded in the FDA approval studies.

Outcome — A randomized trial compared HTA with rollerball in 276 patients [17,18]. Patients treated with HTA compared with rollerball were less likely to have postoperative hematometra (1 versus 6 percent), but they were significantly more likely to experience abdominal pain (53 versus 38 percent) and postoperative nausea and vomiting (22 versus 7 percent). Two patients in the HTA group had lower extremity burns due to contact with the device tubing.

At three-year follow-up, patients in the HTA group compared with those in the rollerball group had similar rates of reduced uterine bleeding (94 versus 91 percent) and amenorrhea (53 versus 46 percent). For HTA compared with rollerball, rates of hysterectomy were 9 and 6 percent and of repeat ablation were 2 and 4 percent. Tests of significance were not reported for the three-year follow-up data.

Advantages/disadvantages — The primary advantage of this method is that it can be performed in patients with intracavitary lesions. The circulating hot water will contact the entire endometrial surface regardless of cavity irregularity (figure 6). There is a report of use of HTA in two patients with bicornuate uteri, but ablation in patients with uterine anomalies is not standard practice [19]. (See "Overview of endometrial ablation", section on 'Relative contraindications'.)

Another advantage of HTA is that it is done under direct visualization, so the operator can ensure that the entire uterine lining has been destroyed.

Perioperative pain is a potential disadvantage of HTA. The hysteroscope used has a large diameter (7.8 mm) and hot water stimulates pain from nerve fibers within the myometrium.

In addition, external burns appear to be more frequent following HTA than other NREA procedures. There have been reports of vaginal, perineal, and leg burns from contact with hot water when there was a poor seal on the cervix or when the sheath was removed before the intrauterine fluid has cooled [20-22]. From 2003 to 2006, voluntary reports by device manufacturers to the FDA Manufacturer and User Facility Device database regarding circulating hot water ablation included 54 cases of burns (22 were major burns); it is not possible to calculate the incidence of these injuries, since the total number of procedures performed during this time period is not known [23].

Combined thermal and radiofrequency ablation — A combined thermal and radiofrequency ablation endometrial ablation device (Minerva) was approved by the FDA in 2015 [24]. The mechanism of ablation utilized by the device is mainly heat applied to the endometrium via a silicone membrane with circulating ionized argon gas (the argon gas is heated by radiofrequency current) [25]. In addition, heat is applied to the endometrium by intracavitary fluid produced and retained during the procedure that is heated by the silicone membrane and by direct effects of radiofrequency current on the endometrium.

Uterine requirements — Uterine cavity parameters for combined radiofrequency and thermal ablation are [24]:

●Cervix should be dilated to 7.0 mm.

●Uterine cavity length ≥4 cm.

●Contraindicated in a patient with a narrow uterine cavity – Narrow was not defined in the device instructions, but a cavity width of <2.5 cm was an exclusion criterion in a preclinical study [25].

●Contraindicated in a patient with a prior endometrial ablation by any method.

●Patients with fibroid(s) distorting the uterine cavity or large endometrial polyp(s) (>2 cm) were excluded from preclinical studies [25,26].

Outcome — Studies of the device include:

●A multicenter, single-arm, randomized trial of 153 premenopausal patients with heavy menstrual bleeding assigned to endometrial ablation with the Minerva device or rollerball [26]. At one year, thermal/radiofrequency compared with rollerball resulted in higher rates of menstrual blood volume ≤80 mL (93.1 and 80.4 percent) and amenorrhea (71.6 and 49 percent). There were no intraoperative complications.

●A multicenter prospective study of 105 premenopausal patients with menorrhagia and dysfunctional uterine bleeding treated with Minerva ablation reported that at one year, 96.2 percent achieved a target reduction of menstrual bleeding based on a pictorial blood loss assessment chart and 69.5 percent were amenorrheic [25]. No intraoperative complications were reported.

Advantages/disadvantages — The main advantage of the combined thermal and radiofrequency endometrial ablation system is the high amenorrhea rate reported in the randomized trial [26]. Another advantage is the relatively low power setting of approximately 40 watts used with this device. The disadvantage with this device is the lack of data regarding long-term outcomes in terms of hysterectomy rate, or other potential late occurring complications, such as hematometra.

Vapor ablation — The vapor ablation device (Mara) uses water vapor to ablate the endometrium. A disposable handheld device is inserted through the cervix and into the uterus to deliver vapor for 120 seconds to ablate endometrial tissue. To use this system, the vapor probe is inserted inside the uterine cavity, after which three positioning balloons are inflated to seal the uterine cavity. A uterine cavity integrity test is performed to ensure the absence of vapor leaks, and a lumen patency test is performed to confirm that the vapor probe is positioned unobstructed by blood or tissue. Vapor delivery is then delivered for 140 seconds. The first 20 seconds of vapor delivery displaces the remaining saline from the patency test and then ablation is carried out for 120 seconds. During that time, the vapor generator regulates the vapor pressure based on feedback from a pressure sensor near the distal tip of the vapor probe and monitors temperature via a thermocouple on a positioning probe.

Uterine requirements — Uterine parameters for Mara ablation are:

●Sounded uterine cavity length ≥6 to ≤12 cm

●Any uterine width

●Cervical dilation 5.8 mm (usually does not require dilation)

Of note, no International Federation of Gynecology and Obstetrics (FIGO) type 0 or 1 fibroids were included in the pivotal trial (two were FIGO type 2, four were FIGO type 3), so efficacy is uncertain in patients with such fibroids [27].

Outcomes — The vapor ablation system was evaluated in a prospective study of 155 subjects [27]. The primary effectiveness end point was a reduction in menstrual blood loss, as measured by a Pictorial Blood Loss Assessment Chart (PBLAC) score of <75 at one year after ablation . At 12 months, 78.7 percent of patients had a PBLAC score <75, and the amenorrhea rate was 19.4 percent. At 12 months, 91 percent of patients were very satisfied or satisfied.

Advantages/disadvantages — The vapor ablation has the advantage of providing a soft, flexible tip for insertion through the endocervical canal that eliminates the requirement to touch the uterine fundus and can essentially be performed without cervical dilation. This device also does not require endometrial preparation; studies evaluating its use were performed during the early proliferative phase of the menstrual cycle.

Other — The following ablation methods are not available for clinical use in the United States.

Microwave — Microwave Endometrial Ablation (MEA) is a 9.2 GHz, 30 watt, microwave system (figure 7). When inserted into the uterine cavity, this energy will produce a tissue temperature of 75 to 85°C at a depth of 6 mm. In order to treat the entire uterine cavity, the surgeon moves the probe from cornu to cornu and across the lower uterine segment until the entire endometrium has reached the desired temperature. Total treatment time is three to five minutes. Unlike other NREA devices, the probe is reusable.

The manufacturer of MEA advises hysteroscopic evaluation before and after ablation, in contrast with other NREA devices.

Uterine requirements — Uterine parameters for MEA ablation are [3]:

●Diameter of device 8.5 mm.

●Sounded cavity length ≥6 to ≤12 cm is advised by the manufacturer, although the device was studied in patients with a cavity length of up to 14 cm.

●Patients with submucosal leiomyomas that do not obstruct treatment access were included in the studies for FDA approval.

Outcome — A randomized trial compared MEA with endometrial resection in 263 patients [28,29]. Perioperative complications included a uterine perforation in each treatment group. Excessive intraoperative bleeding occurred in five patients in the resection group and none in the MEA group; however, three patients treated with MEA were readmitted with secondary hemorrhage. In patients followed for 10 or more years, those treated with MEA compared with resection had similar rates of amenorrhea (83 and 88 percent). The rate of repeat ablation was similar in patients treated with MEA compared with resection (1 versus 2 percent); however, the hysterectomy rate differed significantly (17 versus 28 percent).

Advantages/disadvantages — The labeling from the manufacturer of this device includes the treatment of patients with small submucosal leiomyomas (≤3 cm). The uterine cavity size maximum is larger than with the other NREA devices (12 to 14 cm versus 10 cm).

The manufacturer of MEA advises extra precautions that are not advised for the other NREA devices, including preoperative measurement of the thickness of the myometrium and pre- and postoperative hysteroscopy. These may serve as barriers for the use of this method for surgeons and patients.

These requirements were likely added because prior to the introduction of MEA in the United States, there were case reports from Europe in which bowel burns occurred in patients with no perforation of the uterus [30]. The etiology was presumed to be passage of microwave energy through the uterine walls. As a result, the FDA trial required that ultrasound be performed prior to the procedure and that the myometrium be at least 1 cm in thickness in all areas. The potential risk of ablation-associated injury in patients with thinning of the myometrium is not limited to microwave ablation. (See "Overview of endometrial ablation", section on 'Relative contraindications'.)

Hot liquid-filled balloons — Hot liquid-filled balloon ablation is also referred to as thermal balloon ablation. There are three available brands of hot liquid-filled balloons for endometrial ablation. ThermaChoice (figure 8A-B) is FDA-approved and Cavaterm and Thermablate EAS are available only outside the United States.

All three devices utilize a silicon balloon which is inserted through the cervix into the uterine cavity via a probe [11,31,32]. The balloon is expanded to a pressure of 160 to 220 mmHg with either 5 percent dextrose in water (ThermaChoice), glycine (Cavaterm), or glycerine (Thermablate EAS). For ThermaChoice and Cavaterm, the fluid is heated to approximately 68 to 87°C and ablation requires 8 to 10 minutes. Thermablate uses a higher temperature (173°C) and has shorter ablation time (two minutes).

Uterine requirements — Uterine cavity and cervical dilation parameters for ThermaChoice ablation are [11]:

●Diameter of device 5.5 mm.

●Sounded cavity length ≥6 to ≤10 cm.

●Patients with submucosal leiomyomas were excluded from the FDA approval studies.

Outcome — Studies with long-term follow-up report a wide range of treatment results. In patients who underwent hot liquid-filled balloon ablation with either ThermaChoice, Cavaterm, or an unspecified device and were followed for four or more years, there was reduced uterine bleeding in 22 to 81 percent and amenorrhea in 23 to 58 percent [33-35]. Repeat ablation was performed in 5 to 11 percent, and hysterectomy in 2 to 13 percent.

It is unclear whether these long-term data apply to current versions of the hot liquid-filled balloon devices, since two of the devices have been revised (ThermaChoice III and Cavaterm plus) and Thermablate was introduced later than the other devices and follows a different protocol. For the current version of each of the devices, the reported rates of treatment success and failure are:

●ThermaChoice III – A prospective study of 148 patients followed for 12 months reported reduced bleeding in 31 percent and amenorrhea in 66 percent [36]. No patient had undergone re-ablation or hysterectomy.

●Cavaterm plus – A prospective study of 220 patients followed for 19 months reported reduced bleeding or amenorrhea in 74 to 83 percent [37]. No patient had undergone re-ablation, but 15 percent had undergone, or were planning, hysterectomy.

●Thermablate EAS – A prospective study of 47 patients followed for 12 months reported reduced bleeding or amenorrhea in 77 percent [38]. There were no reports of re-ablation or hysterectomy.

Advantages/disadvantages — Hot liquid-filled balloon techniques may cause more perioperative pain than other NREA techniques (see 'Perioperative pain' below). The likely mechanism of this is the stimulation of pain fibers by both the heat and uterine distention pressure produced during the procedure. However, with adequate preoperative analgesia (eg, nonsteroidal anti-inflammatory drugs, oral narcotics) and a paracervical block, the procedure can be performed in an office setting in appropriately selected patients.

ThermaChoice was not evaluated in the FDA approval studies for use in patients with intracavitary lesions. However, some data suggest that hot liquid-filled balloon ablation is successful in this population. Hot liquid-filled balloon ablation was used successfully in 45 patients with submucosal fibroids ≤3 cm in a randomized trial comparing balloon versus rollerball ablation [39,40].

An additional disadvantage is that hot liquid-filled balloon techniques cannot be used in patients with intracavitary lesions since ablation occurs only where the balloon is in contact with the endometrium.

While there is one report of successful use of a liquid balloon in a patient with bicornuate uterus, endometrial ablation in patients with uterine anomalies is not standard practice [41]. (See "Overview of endometrial ablation", section on 'Relative contraindications'.)

CHOOSING AMONG TECHNIQUES — All of the endometrial ablation devices have similar efficacy, complication rates (low), and reduce uterine bleeding in the majority of patients. As each device has advantages and disadvantages, surgeons should determine which device is most appropriate in their practice.

In the absence of differences in efficacy and complications, choosing among the NREA methods is based on the following factors:

●Uterine characteristics (cavity size and the presence of intracavitary lesions).

●Ease of preoperative preparation.

●Surgeon familiarity and preference.

●Device availability.

●Factors that facilitate use in an office setting and/or under local anesthesia (eg, operative duration, perioperative pain). Office use offers benefits of greater patient acceptability, ease of scheduling, and reduced expense. Many surgeons do not have the office set-up to perform ablation; however, use of local anesthesia has fewer risks and adverse effects than general anesthesia, regardless of the operative setting. All NREA methods can be performed in an office setting and/or under local anesthesia, but some are more amenable to this approach than others (eg, shorter operative duration, less perioperative pain). (See "Overview of endometrial ablation", section on 'Operative setting' and "Overview of endometrial ablation", section on 'Anesthesia'.)

Efficacy — The various NREA devices appear to have similar efficacy, as measured by rates of amenorrhea, patient satisfaction, repeat ablation, and subsequent hysterectomy [42-46].

In a meta-analysis of 53 studies (including 24 randomized trials) and over 48,000 patients managed with NREA, rates of subsequent hysterectomy were similar among the different methods (eg, thermal balloon, microwave, radiofrequency) through 120 months of follow-up [47]. For all methods, the risk of hysterectomy increased with increased follow-up duration with a pooled hysterectomy rate of 4.3 (29 studies), 12.4 (six studies), and 21.3 percent (two studies) at 12, 60, and 120 months, respectively.

Complications — Complications of NREA are discussed separately. (See "Overview of endometrial ablation", section on 'Complications'.)

In randomized trials evaluating bipolar radiofrequency, hot liquid-filled balloon, circulating hot water, and microwave endometrial ablation (MEA), no major operative complications were reported [42,45,48].

Thermal injury (ie, burns to the vagina, vulva, or thighs) are a rare, but serious, complication that is associated mainly with circulating hot water ablation. Only a few cases of this complication have been reported by device manufacturers to the FDA Manufacturer and User Facility Device database [22]. Further study of the risk of thermal injury with HTA ablation is needed. (See 'Circulating hot water (hydrothermal)' above.)

Patients with leiomyomas or polyps

●Submucosal leiomyomas – The treatment of submucosal fibroids at the time of NREA is understudied. A theoretical concern includes the transfer of energy during NREA through a partially resected fibroid, which may absorb energy differently than myometrium.

For most patients with submucosal fibroids undergoing NREA, we suggest use of microwave ablation (when available) or cryoablation rather than other NREA methods since these devices were evaluated in the FDA approval studies in patients with small submucosal or intramural fibroids. Microwave ablation has the additional advantage of allowing for a larger cavity size than other methods (12 to 14 versus 10 cm). Although radiofrequency ablation and hot liquid-filled balloon ablation were not initially evaluated in patients with intracavitary lesions (submucosal fibroids, endometrial polyps), some data suggest that these methods can be used effectively in this population and labeling for circulating hot water ablation permits use in patients with submucosal fibroids that are ≤4 cm. Limited data are available for the vapor ablation with fibroids. (see 'Bipolar radiofrequency' above and 'Hot liquid-filled balloons' above and 'Vapor ablation' above). Further study of this issue is needed.

It is unclear whether a combined procedure is more effective at improving uterine bleeding symptoms than myomectomy alone. This is discussed in more detail separately. (See "Overview of endometrial ablation", section on 'Factors associated with treatment failure'.)

●Endometrial polyps – Endometrial polyps can generally be easily removed prior to endometrial ablation. Patients with small endometrial polyps (≤2 cm) were included in the FDA approval studies for the microwave, bipolar radiofrequency, and ThermaChoice hot liquid-filled balloon devices.

Use of endometrial ablation in patients with intracavitary lesions is discussed in more detail separately. (See "Overview of endometrial ablation", section on 'Factors associated with treatment failure'.)

Preoperative preparation

●Endometrial sampling – Endometrial sampling is performed in all patients prior to endometrial ablation to exclude endometrial hyperplasia or cancer. This is discussed in detail separately. (See "Overview of endometrial ablation", section on 'Endometrial sampling'.)

●Assessment of the uterine cavity and evaluation of myometrial thinning – The uterine cavity should be assessed for the presence of intracavitary lesions (eg, myomas, endometrial polyps), or other abnormalities (eg, uterine septum) that may interfere, or be removed concomitantly, with endometrial ablation. (See 'Patients with leiomyomas or polyps' above and "Overview of endometrial ablation", section on 'Assessment of the uterus'.)

Patients with a history of transmural uterine surgery (eg, cesarean birth, myomectomy) should also be evaluated for myometrial thinning since ablation in patients with severe myometrial thinning can potentially result in visceral injury. Microwave ablation requires this measurement in all patients. However, this requirement does not add to the relative inconvenience of the procedure, since uterine imaging is required prior to all NREA procedures. This is discussed in more detail separately. (See "Overview of endometrial ablation", section on 'Relative contraindications'.)

●Endometrial preparation – Endometrial preparation is advised by the manufacturer used for all NREA procedures with the exception of the bipolar radiofrequency and the Mara devices (see 'Bipolar radiofrequency' above and 'Vapor ablation' above). The other device manufacturers advise 30 to 60 days of pretreatment with a gonadotropin-releasing hormone antagonist (eg, intramuscular leuprolide 3.75 mg/month); preparation for ThermaChoice can be either hormonal suppression or uterine curettage.

Methods that do not require hormonal suppression (eg, Novasure, Mara) avoid the drug-associated 30- to 60-day delay and adverse effects (eg, menopausal symptoms).

Endometrial preparation for endometrial ablation is discussed in detail separately. (See "Overview of endometrial ablation", section on 'Endometrial preparation'.)

Operative duration — A shorter procedure is easier for a patient to tolerate under local anesthesia. Also, differences in operative duration impact upon a surgeon's operative or office schedule.

The duration of energy delivery of the NREA procedures, from shortest to longest, are:

●NovaSure bipolar radiofrequency (90 to 120 seconds)

●Minerva thermal/radiofrequency (120 seconds)

●Mara vapor system (120 seconds)

●Cerene cryoablation (2.5 minutes)

●MEA (3 to 5 minutes)

●ThermaChoice hot liquid-filled balloon (8 minutes)

●HTA circulating hot water (10 minutes)

●Her Option cryoablation (10 minutes)

Thermablate EAS hot liquid-filled balloon ablation has an operative time of just two minutes, but it is not currently available in the United States.

These times do not include other parts of the procedure, which are similar across ablation methods, including patient set-up and anesthesia time.

Perioperative pain — Pain is stimulated by cervical dilation, uterine distention, and burning of the endometrium (which stimulates pain fibers within the endometrium and myometrium).

There are few comparative data regarding perioperative pain across NREA methods [49]. Bipolar radiofrequency ablation and MEA appear to be associated with less perioperative pain than hot liquid-filled balloon procedures, based on data from randomized trials [45,48,49]. In the randomized trial including 57 patients undergoing Novasure or Cavaterm balloon ablation discussed above (see 'Efficacy' above), perioperative pain was lower in the radiofrequency group [48]. Similarly, in the randomized trial including 320 patients undergoing MEA or ThermaChoice III ablation discussed above (see 'Efficacy' above), patients in the MEA group had a lower rate of using postoperative opiates (80 versus 89 percent) and antiemetics (26 versus 48 percent) compared with patients in the balloon group [45].

Cryoablation may result in even less perioperative pain as these devices use probes with the smallest diameter (approximately 5 mm; similar to ThermaChoice hot liquid-filled balloon), do not require uterine distention, and provide cryoanesthesia instead of heat (used with all other NREA devices) to burn the endometrium. Comparative data are needed to evaluate this theory.

POSTOPERATIVE CARE — Postoperative care and other follow-up issues for endometrial ablation is discussed separately. (See "Overview of endometrial ablation", section on 'Follow-up'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Gynecologic surgery".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Endometrial ablation (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Terminology – Non-resectoscopic endometrial ablation (NREA) is a treatment for abnormal uterine bleeding that is performed with a device which is inserted into the uterine cavity and delivers energy to uniformly destroy the uterine lining. (See 'Introduction' above.)

●Devices – NREA devices include bipolar radiofrequency (NovaSure) (figure 1B), hot liquid-filled balloon (ThermaChoice, Cavaterm, Thermablate), cryotherapy (Her Option, Cerene) (figure 2A), circulating hot water (Hydro ThermAblator) (figure 5), microwave endometrial ablation (MEA) (figure 7), combined thermal and bipolar radiofrequency (Minerva), and vapor ablation (Mara); not all of these devices are available in the United States. (See 'Non-resectoscopic ablation devices' above.)

●Methods – Uterine requirements and operative duration for each procedure are listed in the table (table 1). In general, endometrial destruction is achieved when the tissue is heated to 65°C or cooled to -60°C. (See 'Ablation methods' above.)

●Preoperative preparation

•Uterine and endometrial assessment – The uterine cavity should be assessed for the presence of intracavitary lesions (eg, myomas, endometrial polyps) and other abnormalities (eg, uterine septum, myometrial thinning). Endometrial sampling is performed in all patients prior to endometrial ablation to exclude endometrial hyperplasia or cancer. (See 'Preoperative preparation' above.)

•Endometrial preparation – Endometrial preparation (eg, 30 to 60 days of a gonadotropin-releasing hormone antagonist such as intramuscular leuprolide 3.75 mg/month) is advised for all NREA procedures except for the bipolar radiofrequency and the Mara devices. Preparation for ThermaChoice can be either hormonal suppression or uterine curettage. This is discussed in more detail separately. (See 'Preoperative preparation' above and "Overview of endometrial ablation", section on 'Endometrial preparation'.)

●Choosing among techniques

•Efficacy and complications – All the NREA devices appear to have similar efficacy and complication rates. Specific methods have advantages and disadvantages regarding operative duration, perioperative pain, and visualization. Surgeon familiarity, preference, and device availability, often determine which device is used. (See 'Efficacy' above and 'Complications' above.)

•Patients with intracavitary lesions – For patients with small (≤4 cm) submucosal fibroids or endometrial polyps undergoing NREA, we suggest MEA or cryoablation rather than other NREA methods (Grade 2C). The use of resectoscopic endometrial ablation (REA) for patients with intracavitary lesions is discussed in detail separately. (See 'Patients with leiomyomas or polyps' above and "Endometrial ablation or resection: Resectoscopic techniques", section on 'Patients with leiomyomas or polyps'.)

●Postoperative care – Postoperative care and other follow-up issues for endometrial ablation is discussed separately. (See 'Postoperative care' above and "Overview of endometrial ablation", section on 'Follow-up'.)