Endometrial Ablation

Endometrial ablation is an outpatient procedure that removes or destroys the endometrial layers. The opposing walls of the myometrium collapse onto each other, and the damaged tissue contracts and develops into a scar. ^[1] Any endometrium remaining after the ablation is trapped beneath the scar, preventing further bleeding. Estimation of the number of endometrial ablations performed each year is difficult, because many are performed in the office setting.

Endometrial ablation is performed to reduce menstrual bleeding, such as menorrhagia. Menorrhagia is menstrual bleeding that is heavy in amount or duration and that occurs at regular intervals. Loss of more than 80 mL of blood per menstrual cycle is considered abnormal. Menorrhagia affects approximately 10-30% of premenopausal women and up to 50% of perimenopausal women. Abnormal bleeding is a common reason for outpatient gynecologic visits and is one of the most common causes for surgery among women.

In the past, hysterectomy was the most common surgical treatment for menorrhagia; 10% of hysterectomies are performed for menstrual disorders. Although endometrial ablation is not a pure substitute for hysterectomy, it offers patients a fast, outpatient procedure, with little to no postoperative downtime; It also affords a reasonable surgical option for those patients who have failed, declined, or are ineligible for medical therapy, and who also desire to avoid hysterectomy. ^{[2, 3, 4, 5]}

The etiology of menorrhagia may not always be known, but endometrial hyperplasia or carcinoma must be excluded as the cause of bleeding before proceeding to the endometrial ablation.

Although the first medical literature reports of endometrial destructive procedures are older than 100 years, widespread adoption of this modality did not occur until the advent of hysteroscopically guided techniques. ^{[2, 6, 7, 8, 9, 10]} Until the mid-1990s, hysteroscopically guided ablation (resectoscopic endometrial ablation [REA]) using laser, fulguration, or vaporization techniques was the most common approach. ^{[11, 12, 13, 14]}

Since then, global endometrial ablation (GEA) devices, developed to treat all areas of the endometrial cavity simultaneously or with minimal manipulation of the device, have simplified the application of endometrial ablation and extended the location of the procedure to the office setting. These devices require less operator time and training to achieve excellent results. To date, 5 GEA devices have been approved by the US Food and Drug Administration (FDA) for minimally invasive treatment of idiopathic menorrhagia (see Equipment).

GEA techniques have improved the ease with which gynecologic surgeons can effectively treat abnormal uterine bleeding of benign origin. Improvements in these devices have come quickly, including the ability to treat submucosal fibroids and irregularly shaped endometrial cavities. The high overall success and patient satisfaction rates reported with GEA techniques make them a viable option for conservative surgical management.

Endometrial ablation is indicated for the treatment of menorrhagia in premenopausal or perimenopausal women with normal endometrial cavities. It may also be indicated for the treatment of postmenopausal bleeding of benign origin. Premenopausal patients should be advised that whereas endometrial ablation generally decreases menstrual bleeding, a small percentage of patients will experience no change.

Patients with anovulatory bleeding and bleeding secondary to fibroids are potential candidates for the procedure, but they should be aware that endometrial ablation does not specifically address ovulatory dysfunction and, by itself, does not remove fibroids. Thus, these patients may be at higher risk of unsatisfactory results and may be better served by other treatments, either medical or surgical.

The GEA devices currently available are approved for the treatment of abnormal uterine bleeding and intramural or submucosal fibroids smaller than 2 cm. Only the microwave endometrial ablation device (see Equipment) is approved for use in the presence of submucosal fibroids of up to 3 cm.

Some of the previous contraindications to endometrial ablations, including irregular cavity shape and larger-than-average cavity size, have been addressed by some of the global endometrial ablation devices. The microwave endometrial ablation device is FDA-approved for uteri measuring up to 14 cm, and the hydrothermal ablation device (see Equipment) is FDA-approved for irregularly shaped cavities.

The basic preoperative criteria for any patient opting for endometrial ablation are, at a minimum, the following:

• Abnormal uterine bleeding of benign etiology (as evidenced by preoperative endometrial sampling and histologically benign findings)

• No desire for future fertility

• Desire to retain the uterus or to avoid hysterectomy

Although failure of medical therapy is not a prerequisite for the procedure, it is an important consideration.

Absolute contraindications for endometrial ablation include the following:

• Pregnancy or a desire for future pregnancy

• Active urogenital or pelvic infection (eg, cystitis, vaginitis, cervicitis, endometritis, salpingitis, pelvic inflammatory disease [PID], or tubo-ovarian abscess [TOA])

• Suspected or documented premalignant or malignant conditions of the endometrium or uterus

Additional contraindications may include the following:

• Recent uterine infection

• A cavity that exceeds the device’s functional length and uterine diameter

• Hydrosalpinx

• History of classical cesarean section

• History of a transmural myomectomy

• Uterine anomalies

Infections should be treated preoperatively. When possible, repeat testing to document resolution should be completed preoperatively. In situations where posttreatment testing is not standard (eg, PID or TOA), clinical criteria should be used to document resolution of the infection.

Premalignant abnormalities of the endometrium should be treated with high-dose progestins or surgery, depending on the abnormality. Malignant conditions of the endometrium are treated by means of hysterectomy, with or without adjuvant radiation or chemotherapy. Endometrial ablation should not be performed in patients who have or are suspected of having either of these disease processes.

Therapy with the levonorgestrel-releasing intrauterine system (LNG-IUS) should be given particular consideration in patients with comorbid conditions predisposing to a higher risk of endometrial hyperplasia or carcinoma (eg, obesity, diabetes, family history, or anovulation). Endometrial carcinoma has been reported in patients who previously underwent endometrial ablation ^{[15, 16, 17, 18, 19, 20, 21]} ; thus, definitive surgical therapy with hysterectomy should be considered in high-risk patients, unless they are poor surgical candidates.

The bipolar energy ablation device (see Equipment) and the microwave ablation device should not be used in patients with previous classical cesarean delivery or transmural myomectomy out of concern for possible transmural thermal injury to the abdominal and pelvic organs. In addition, preoperative ultrasonographic evaluation must verify that transmural thickness is at least 1 cm in all areas of the uterus before microwave ablation is done, and intraoperative hysteroscopy is recommended to ensure uterine wall integrity. ^{[22, 23]}

Finally, reablation with a GEA device should be avoided because of the theoretical increased likelihood of transmural energy transmission. Repeat GEA is not approved by the FDA.

Satisfaction rate with endometrial ablation is high. Compared with hysterectomy, endometrial ablation leads to fewer hospital stays and complications. In addition, it is more cost-effective than a hysterectomy, even when the need for repeat procedures or subsequent hysterectomy is factored in. Increased operator skill level and technique lead to decreased operating time and complications, particularly with REA techniques.

GEA has been shown to be at least as effective as REA. One of the challenges in the comparison of GEA techniques is the relative lack of direct comparison data for the various GEA devices. However, many of these devices have been tested against the previously standard resectoscopic methods.

One study compared bipolar radiofrequency (RF) endometrial ablation with hydrothermablation for the treatment of menorrhagia at 5-year follow-up. Results showed that bipolar RF ablation was more effective and led to fewer surgical reinterventions. ^[24]

A retrospective study by Wyatt et al indicated that about half of women with preoperative heavy menstrual bleeding will experience pain resolution following RF endometrial ablation. In the study, 100 women reported preoperative dysmenorrhea, with postprocedure symptom resolution achieved in 48 of them (48%). The study also found that while postablation resolution of dysmenorrhea was characterized by a decrease in bleeding volume, it was not associated with a reduction in bleeding frequency. ^[25]

In a study by El-Nashar et al, the rate of failure (defined as bleeding or pain after endometrial ablation that required hysterectomy or reablation) for GEA was 16-30% at 5 years. ^[26] Failure was most likely to occur in women younger than 45 years and in women with parity of 5 or more, prior tubal ligation, and a history of dysmenorrhea. After endometrial ablation, 11-36% of women had a repeat ablation or other uterine-sparing procedure.

A review and meta-analysis assessed failure rates for second-generation endometrial ablation. Of the 10 parameters assessed (age, myomas, history of tubal ligation, body mass index, parity, preexisting dysmenorrhea, caesarean delivery, bleeding pattern, uterus position, and uterus length), dysmenorrhea at baseline was the strongest predictor of ablation failure. ^[27]

Hysterectomy is superior to ablation in attained amenorrhea. After ablation, the rate of women who eventually go on to have a hysterectomy has been reported as 20-30%. In the study by El-Nashar et al, predictors of amenorrhea included age greater than 45 years, uterine length less than 9 cm, endometrial thickness less than 4 mm, and use of radiofrequency ablation. ^[26]

Outcome measures for GEA have included bleeding assessment surveys, overall satisfaction assessment surveys, eumenorrhea rates, and amenorrhea rates. For ease of comparison, amenorrhea outcomes are reviewed here. It is noteworthy that for all of the global techniques, assessment of combined amenorrhea, hypomenorrhea, and eumenorrhea rates reveals very high success rates and overall satisfaction rates, typically approaching or exceeding 90%.

Although 1 randomized trial showed that endometrial ablation with cryotherapy was less likely than rollerball endometrial ablation to induce amenorrhea at 1 year, initial studies using a freeze time longer than 10 minutes (current FDA protocol) have resulted in amenorrhea rates higher than 60%. ^[28] Larger studies are under way to confirm these data.

Randomized trials comparing thermal balloon ablation with rollerball ablation showed that amenorrhea was less likely with the former at 12 and 36 months; however, there were no differences in amenorrhea rates at 5 years. ^[28]

A comparison of hydrothermal ablation with rollerball ablation showed that the initial amenorrhea rates were similar for the 2 techniques and that the rates remained relatively similar at the 3-year mark. ^[29]

Long-term follow-up studies of bipolar energy ablation showed an initial amenorrhea rate of 51% and a 65% rate at the 3-year mark. ^[30] Comparisons of this technique with thermal balloon ablation have been performed, with higher amenorrhea rates reported for the former. ^[31] In addition, bipolar energy ablation is associated with lower intraoperative and postoperative pain than thermal balloon ablation is. ^[32]

With microwave ablation, follow-up studies have revealed a 38% amenorrhea rate at 3 years. At 1 year, 2 years, or 5 years, amenorrhea rates were not significantly different from those seen with endometrial resection. ^[28]

The use of the levonorgestrel-releasing intrauterine contraceptive system has been found to be as effective as GEA for treating menorrhagia in women with normal uterine cavities. ^[33]