Menorrhagia is one of the most common gynecologic conditions affecting reproductive-aged women. Up to one in five women in this age group suffer from the problem.In addition, there are more than 650,000 hysterectomies performed each year in the US,nearly half of these patients have menorrhagia.

Overview of treatment

Traditional treatment options for patients with menorrhagia include drug therapy, dilatation and curettage, and hysterectomy. Each of these therapies, however, has significant limitations. Medical management is usually the first-line therapy and it typically consists of progestins or oral contraceptives. Yet over 65% of women in a recent survey said they wanted to avoid taking hormones.

Over the last several years, several simpler endometrial ablation procedures have been developed. They're usually rapid and can be performed with minimal training. The efficacy and patient satisfaction rates are very high—usually above 90%—and the complication rates are quite low, especially when compared with hysterectomy. Additionally, patients return to normal activities within a few days, avoiding the complications common to gynecologic surgery, and they can, of course, maintain their organs and hormones.

Hysteroscopic rollerball ablation reduces or eliminates bleeding and is minimally invasive; the operative time is relatively short, and the recovery is usually rapid. Its limitations include the need for general anesthesia in most cases, risks associated with distension media, and a need for relatively advanced hysteroscopic skills.
Among several techniques of endometrial ablation, unique properties of cryoablation make this procedure very attractive. Clinicians can use real-time U/S to monitor freeze depth; patients are usually comfortable during the procedure and there's no need for IV sedation; the technique can be used to treat a broad range of uterine cavity sizes and shapes, and there's minimal postprocedure scarring. Cryoablation is also the most suitable ablation technique for office-based treatments.

History of cryosurgery

The history of cryotherapy in gynecology began during the 20th century. Weitzner used dry ice rods to treat cervicitis in 1935. Townsend and Ostergard talked about cryosurgery to treat "benign" and premalignant cervical disease, condyloma, vaginal intraepithelial neoplasia (VAIN), and vulvar intraepithelial neoplasia (VIN) in the late 1960s.3

Cahan was the first to describe endometrial cryoablation in 1967.4 Droegemueller performed a series of cases in the early 1970s.5,6

However, as an ablative technique, it was ignored because there was no suitable system to deliver the cryogen to the cavity.  A closed circuit system was developed and introduced in the late 1990s.  It is the only technique that can easily be performed in a physician’s office with little or no sedation and local block. No preoperative medication is necessary.  Initial results were disappointing because an effort was made to make it “an auto-ablative” method, which it is not.  Newer studies whereby the duration of the  cryosurgical sessions are related to uterine cavity size and treatment results comparable to the other ablative techniques have been noted. 

Complications are extremely rare.  It has the added advantage in that treatment is performed with real time ultrasound guidance which dramatically reduces the risk of injury to surrounding organs.

Procedure of cryosurgery
A cryoablation system (AMS Gynecology, Minnetonka, Minn.), gained FDA approval is used for endometrial cryoablation (Figure 1). The system uses a proprietary mix of gasses to reach very low temperatures, typically below 100°C, yet it's small enough to be easily used in a physician's office setting. The system uses a novel closed-circuit gas system, thus, no refillable gas tanks are required. In addition, the probe has a diameter of only 5.5 mm, making it more comfortable for the patient and in most instances allowing performance of the procedure without cervical dilation.

FIGURE 1. Her Option Cryoablation Therapy: console and disposable probe
A probe (also called cryoprobe) is inserted through the vagina and cervix into the uterus and is cooled by passing either liquid nitrogen or a compressed gas mixture through it. The tip of the probe is the site of freezing and is placed in the top part of the uterus. Activating the freeze cycle of the probe generates an ice ball in the uterus which destroys the target area of endometrial tissue. The freeze cycle is followed by a heat (thaw) cycle which allows the probe to be removed.

Generally,the procedure includes freezes to 4 minutes in one cornu and 6 minutes in the contralateral cornu, most physicians use their judgment regarding freeze patterns and times based on the size and shape of the uterine cavity and the feedback from the U/S. Extended freeze patterns have included a short 4-minute midline freeze at the fundus prior to a 4- to 8-minute freeze in each cornu. In uteri that sound to 8 to 9 cm or longer, a short 4-minute pull-back freeze to treat the lower uterine segment is commonly performed.

Ultrasound is used to monitor the position of the probe and depth of freezing across the endometrium. As the cryoprobe freezes tissue, the ice-front is easily identified by its echogenicity and shadowing behind it. Key landmarks during ultrasound monitoring are the bladder (which should be full), the uterus, and the freezing zone, which appears as a dark-black arc. One can easily identify the probe in the uterus as an echogenic white line (in the sagittal view) or a point (in the transverse view).


FIGURE 2. Probe placement visualized with ultrasound guidance

FIGURE 3. Real-time monitoring of freeze zone

Clinical results

Patient comfort during the procedure has been documented in a series of 110 patients treated in four standard gynecology office settings without IV sedation.9 These women were simply given a paracervical block, with an oral nonsteroidal anti-inflammatory drug (NSAID), diazepam, or both. They were asked about their comfort during and after the procedure; 96% of patients were comfortable or had only slight discomfort. All procedures were successfully completed.

9. Levy B, Isaacson K. Office-based cryoablation of the endometrium. ACOG poster, 2003.

One multicenter, randomized controlled study compared cryoablation to rollerball electroablation in 279 patients, and found that endometrial cryoablation is effective and safe.8

8.Duleba AJ, Heppard MC, Soderstrom RM, et al. A randomized study comparing endometrial cryoablation and rollerball electroablation for treatment of dysfunctional uterine bleeding. J Am Assoc Gynecol Laparosc. 2003;10:17-26.

The trial included premenopausal women aged 30 to 50 with a history of dysfunctional uterine bleeding. The women in the cryoablation group had significantly greater menorrhagia than the rollerball group. All patients had failed previous therapy, and were no longer interested in getting pregnant. The study excluded patients with a uterine cavity greater than 10 cm and myomas greater than 2 cm.

Successful outcomes, based on a pictorial bleeding assessment chart (PBAC) score of 75 or less in the absence of retreatment, were found in 85% of the cryoablation group at 1 year, similar to the 89% success rate found with rollerball. Two- and 3-year follow-up showed no degradation in the results.10

10. Townsend DE, Duleba AJ, Wilkes MM. Durability of treatment effects after endometrial cryoablation versus rollerball electroablation for abnormal uterine bleeding: two-year results of a multicenter randomized trial. Am J Obstet Gynecol. 2003;188:699-701.

As important as the objective success rates, patients were also very satisfied with the procedure and reported marked improvement in their quality of life. At 2-year follow-up, 91% of the cryoablation patients and 88% of the rollerball patients were extremely satisfied with the results of the treatment. Seventy-seven percent of the cryoablation patients and 81% of the rollerball patients reported much less menstrual pain, or none at all. Additionally, 67% of cryoablation patients and 79% of the rollerball patients reported absent or mild PMS symptoms by 2 years postprocedure.
The study followed retreatment and hysterectomy rates during the 3-year follow-up. Retreatment rates were similar at 2 years for both therapies, at 12% to 13%.

However, the cryoablation patients had a significantly lower 3-year cumulative hysterectomy rate (8% vs. 15%).

Discussion

Many clinicians believe that endometrial ablation leads to Asherman's syndrome-like scarring in the uterus. The theory is that adhesions formed in the cavity would induce amenorrhea. There is indeed evidence indicating that heat-based ablation induces adhesions and a scarred, narrow cavity.11,12 A layer of scar tissue behind which viable endometrium can exist has been documented in the literature.13 Using MRI following rollerball ablation, one researcher observed that 95% of patients with amenorrhea had viable endometrium underneath a layer of scar tissue.14

Another investigator reported a postablation tubal ligation syndrome (pelvic pain after ablation and tubal ligation) in one out of 20 women following rollerball ablation at 10-year follow-up.15 These patients were nearly always treated with hysterectomy. A published study on the thermal balloon and rollerball ablation reported a 25% hysterectomy rate at five years, many due to pain and bleeding. All of the studies reported on hysteroscopic findings following endometrial ablation note significant scarring after several heat ablation techniques.

However, few of above syndromes develop after  cryosurgery in which the uterine cavity is minimally altered.  A team of researchers who did a hysteroscopic evaluation after cryoablation in 98 patients found a normal-appearing endometrial cavity outline with both tubalostia visible in all patients, and a bland white cavity surface 3 to 18 months after cryoablation.18 No hematometra or postablation tubal ligation syndrome was noted in any of these patients.
18. Bruno R, Townsend DE. Hysteroscopic Evaluation Following Endometrial Ablation. ACOG 2004.

McCausland has raised a more potentially serious complication of scarring that is hiding an occult endometrial cancer.There is also a concern that the scarring in the cavity could mask signs of endometrial cancer over the long term. There are several cases of endometrial cancer following endometrial ablation in the literature.16,17 However,there are no evidence that the cancer is result from ablation itself.The significance of occult endometrial cancer after endometrial ablation will not be known for decades since the average age of women undergoing ablation is at least 10 to 15 years younger than the peak age incidence of endometrial cancer. Many women undergoing endometrial ablation have many of the stigmata associated with endometrial cancer, i.e., obesity, hypertension, and diabetes.

16. Valle RF, Baggish MS. Endometrial carcinoma after endometrial ablation: high-risk factors predicting its occurrence. Am J Obstet Gynecol. 1998;179(3 Pt 1):569-572.
17. Margolis MT, Thoen LD, Boike GM, et al. Asymptomatic endometrial carcinoma after endometrial ablation. Int J Gynaecol Obstet. 1995;51:255-258.

Conclusion
Endometrial cryoablation is a safe and effective procedure in treatment of dysfunctional uterine bleeding. Its advantages include technical ease of performance, direct ultrasonographic view of depth of ablation, little anesthetic, and avoidance of potential complications related to distention media.

References
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