Endometrial cryoablation, a minimally invasive procedure for abnormal uterine bleeding

Adjuvant approaches to enhance cryosurgery

Molecular adjuvants can be used to enhance the natural destructive mechanisms of freezing within tissue. This review discusses their use in the growing field of combinatorial or adjuvant enhanced cryosurgery for a variety of disease conditions. Two important motivations for adjuvant use are: (1) increased control of the local disease in the area of freezing (i.e., reduced local recurrence of disease) and (2) reduced complications due to over-freezing into adjacent tissues (i.e., reduced normal functional tissue destruction near the treatment site). This review starts with a brief overview of cryosurgical technology including probes and cryogens and major mechanisms of cellular, vascular injury and possible immunological effects due to freeze-thaw treatment in vivo. The review then focuses on adjuvants to each of these mechanisms that make the tissue more sensitive to freeze-thaw injury. Four broad classes of adjuvants are discussed including: thermophysical agents (eutectic forming salts and amino acids), chemotherapuetics, vascular agents and immunomodulators. The key issues of selection, timing, dose and delivery of these adjuvants are then elaborated. Finally, work with a particularly promising vascular adjuvant, TNF-alpha, that shows the ability to destroy all cancer within a cryosurgical iceball is highlighted.

Endometrial ablation for heavy menstrual bleeding

PURPOSE OF REVIEW

This review evaluates the currently available evidence regarding resectoscopic endometrial ablation (REA) and the various nonresectoscopic endometrial ablation (NREA) techniques used for heavy menstrual bleeding.

RECENT FINDINGS

Laser endometrial ablation is now used infrequently, largely because of procedure time, but also because of the cost and training associated with the technique. REA can be performed in a wider spectrum of endometrial cavity configurations than NREA and, at least in expert hands, remains the gold standard. Each of the five available types of NREA device possesses advantages and disadvantages over the others with respect to variables such as treatment time, required cervical dilation, and size and configuration of the endometrial cavity. All provide acceptable results that are comparable to that of REA in expert hands. Serious complications seem to be less common with NREA, but uterine perforation and bowel or other visceral injury can still occur. When endometrial-ablation patients were followed for up to 5 years, repeat surgery rates ranged from 20 to 40%, thereby eroding both the direct and indirect treatment-related resource utilization. Levonorgestrel-releasing intrauterine devices demonstrate similar clinical and patient-satisfaction outcomes to endometrial ablation but can be inserted in the office and allow maintenance of fertility.

SUMMARY

Both REA and NREA provide at least short- to intermediate-term options to hysterectomy for patients with heavy menstrual bleeding and normal or near-normal endometrial cavities. Consequently, the ideal candidates are likely those who are within 5 years of menopause.

Hysteroscopic and nonhysteroscopic endometrial ablation

Endometrial ablation is defined as the elimination of the endometrium by thermal energy or resection. It was introduced in the 1980s as an alternative to hysterectomy to those patients with abnormal uterine bleeding and benign pathology who are unable or unwilling to tolerate traditional therapies. This article explores various endometrial ablation techniques.

Efficacy and satisfaction rate comparing endometrial ablation by rollerball electrocoagulation to uterine balloon thermal ablation in a randomised controlled trial

OBJECTIVE

To compare two methods of endometrial ablation, hysteroscopic rollerball electrocoagulation (RBE) and non-hysteroscopic uterine balloon thermal ablation (Thermachoice trade mark ), regarding efficacy for reducing dysfunctional uterine bleeding and patients satisfaction rate.

METHODS

A randomised controlled study was performed in a teaching hospital at the department of gynaecology. One hundred and thirty-seven premenopausal women with dysfunctional uterine bleeding proved by validated menstrual score list were included. Endometrial ablation by a hysteroscopic or non-hysteroscopic method was performed by one gynaecologist.

RESULTS

Reduction of menstrual blood loss was significantly more successful at 24 months for thermal ablation with uterine balloon. Success rate measured by menstrual score < 185 for rollerball and thermal balloon ablation are equivalent at 12 and 24 months post-operatively. Satisfaction of the patients for both methods at 24 months post-operatively is not significantly different (respective 75% for rollerball and 80% for uterine balloon).

CONCLUSIONS

Endometrial ablation by uterine balloon thermal ablation (Thermachoice trade mark ) is equally effective as hysteroscopic RBE of the endometrium.

Menorrhagia: an update

Menorrhagia is defined as a 'complaint of heavy cyclical menstrual bleeding occurring over several consecutive cycles'. Objectively it is a total menstrual blood loss equal to or greater than 80 ml per menstruation. It is estimated that approximately 30% of women complain of menorrhagia. Excessive bleeding is the main presenting complaint in women referred to gynecologists and it accounts for two-thirds of all hysterectomies, and most of endoscopic endometrial destructive surgery. Thus, menorrhagia is an important healthcare problem. Its etiology, investigation, medical and surgical management are described. In approximately 50% of cases of menorrhagia no pathology is found at hysterectomy. Abnormal levels of prostaglandins or the fibrinolytic system in the endometrium have been implicated. Effective medical treatments suitable for long-term use include intrauterine progestogens, antifibrinolytic agents (tranexamic acid) and nonsteroidal anti-inflammatory agents (mefenamic acid). Over the past decade there has been increasing use of endometrial destructive techniques as an alternative to hysterectomy. Their further refinement and the advent of fibroid embolization has increased the options available to women.

A randomized study comparing endometrial cryoablation and rollerball electroablation for treatment of dysfunctional uterine bleeding

STUDY OBJECTIVE

To determine the effectiveness of endometrial cryoablation in comparison with rollerball electroablation.

DESIGN

Prospective, randomized study (Canadian Task Force classification I).

SETTING

Ten university and private medical centers in the United States.

PATIENTS

Two hundred seventy-nine women with menorrhagia due to benign causes.

INTERVENTION

Endometrial ablation using a Her Option cryoablation device in 193 women and rollerball electroablation in 86.

MEASUREMENTS AND MAIN RESULTS

Women treated by cryoablation received significantly less general anesthesia (46%) than those treated by electroablation (92%). Subjects maintained menstrual diaries for at least one cycle before and for 12 months after the procedure. Success was defined as reduction of menstrual bleeding to a score of 75 or less in the absence of retreatment. Success rates in the cryoablation and electroablation groups were 77.3% and 83.8%, respectively. Bleeding declined by 92% and 94%, respectively. Both procedures led to significant improvements in a broad range of symptoms including menses-related pain, mood, and overall improvement in quality of life.

CONCLUSIONS

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.

Cryosurgical changes in the porcine kidney: histologic analysis with thermal history correlation

Advances in minimally invasive renal cryosurgery have renewed interest in the relative contributions of direct cryothermic and secondary vascular injury-associated ischemic cell injury. Prior studies have evaluated renal cryolesions seven or more days post-ablation and postulated that vascular injury is the primary cell injury mechanism; however, the contributions of direct versus secondary cell injury are not morphologically distinguishable during the healing/repair stage of a cryolesion. While more optimal to evaluate this issue, minimal acute (< or = 3 days) post-ablation histologic data with thermal history correlation exists. This study evaluates three groups of porcine renal cryolesions: Group (1) in vitro non-perfused (n = 5); Group (2) in vivo 2-h post-ablation perfused (n = 5); and Group (3) in vivo 3-day post-ablation perfused (n = 6). The 3.4 mm argon-cooled cryoprobe's thermal history included a 75 degrees C/min cooling rate, -130 degrees C end temperature, 60 degrees C/min thawing rate, and 15-min freeze time. An enthalpy-based mathematical model with a 2-D transient axisymmetric numerical solution with blood flow consideration was used to determine the thermal history within the ice ball. All three groups of cryolesions showed histologically similar central regions of complete cell death (CD) and transition zones of incomplete cell death (TZ). The CD had radii of 1.4, 1.1, and 1.0 cm in the non-perfused, 2-h and 3-day lesions, respectively. Capillary thrombosis was present in the 2-h perfused cryolesions with the addition of TZ arteriolar/venous thrombosis in the 3-day perfused lesions. Thermal modeling revealed the outer CD boundary in all three groups experienced similar thermal histories with an approximately -20 degrees C end temperature and 2 degrees C/min cooling and thawing rates. The presence of similar CD histology and in vitro/in vivo thermal histories in each group suggests that direct cryothermic cell injury, prior to or synchronous with vascular thrombosis, is a primary mediator of cell death in renal cryolesions.

Dysfunctional uterine bleeding: advances in diagnosis and treatment

Dysfunctional uterine bleeding occurs during the reproductive years unrelated to structural uterine abnormalities. Ovulatory dysfunctional uterine bleeding occurs secondary to defects in local endometrial hemostasis; while anovulatory dysfunctional uterine bleeding is a systemic disorder, occurring secondary to endocrinologic, neurochemical, or pharmacologic mechanisms. Evaluation of patients with abnormal uterine bleeding and identifying those with dysfunctional uterine bleeding is achieved with a combination of the following: history; physical examination; and judicious use of laboratory evaluation, endometrial sampling and uterine imaging, with sonographic techniques and/or hysteroscopy. Coagulopathies should be considered as should the notion that intramural and subserosal myomas are unlikely to contribute to AUB. High-quality evidence suggests that medical therapy is frequently successful, and newer approaches, such as local delivery of progestins via intrauterine devices, appear to be particularly promising and devoid of systemic side effects. For those intolerant of medical therapy, and/or for whom fertility is no longer desired, a number of minimally invasive surgical options for hysterectomy now exist and are collectively termed endometrial ablation. Endometrial ablation may be performed with or without hysteroscopic guidance. There is an increasing body of evidence that suggests that nonhysteroscopic endometrial ablation may be at least as effective as hysteroscopic endometrial ablation, even when the hysteroscopic procedure is performed by experts.

GLOBAL ENDOMETRIAL ABLATION

Hysteroscopic endometrial ablation was introduced in the 1980's as an alternative to hysterectomy in women who failed medical management. Global endometrial ablation was introduced in the 1990's as an easier, safe, and equally effective alternative to hysteroscopic ablation. Several devices have been introduced, some of which are still undergoing feasibility studies or clinical trials. These devices include: three hot water intrauterine balloons, two intrauterine free saline solutions, a multielectrode electrocoagulating balloon, a 3-D bipolar electrocoagulation probe, a microwave, a diode fibre laser, and at least three cryoprobes. These devices require less operator skill and no irrigant or distending solutions. All require either heat or cold to destroy the endometrium. Although all devices are promising and have produced impressive preliminary results, the long-term efficacy, complication rates, and cost effectiveness have not been established. This review describes all devices as they appeared chronologically and presents only peer-reviewed data.

Endometrial cryoablation with ultrasound visualization in women undergoing hysterectomy

STUDY OBJECTIVES

To evaluate tissue effects of cryosurgical endometrial ablation in women just before hysterectomy, characterize ultrasound monitoring of freezing, determine the feasibility of a new probe-angling procedure, and assess the safety profile by monitoring serosal surface temperatures.

DESIGN

Single arm safety study enrolling ten women at two centers (Canadian Task Force classification II-2).

SETTING

Two clinical sites. Patients. Ten women scheduled for hysterectomy.

INTERVENTION

Hysterectomy with a new cryosurgical device (First Option, CryoGen, Inc., San Diego, CA) that achieves surface temperatures below -90 inverted exclamation mark C to freeze endometrium.

MEASUREMENTS AND MAIN RESULTS

The freeze protocol involved angling the probe toward each cornu. Maximum ice front diameter at the end of the first angled freeze ranged from 24 to 34 mm, and maximum ice ball diameter at the end of the second freeze ranged from 28 to 37 mm. The margin between the advancing ice front and serosal surface was monitored by ultrasound. In all cases the margin was safe and no reduction in serosal surface temperatures occurred. Depth of necrosis ranged from 9 to 12 mm as determined by tetrazolium staining and electron microscopy, and there was no full-thickness myometrial destruction. Total endometrial destruction was achieved.

CONCLUSION

Cryosurgical ablation of the endometrium with the First Option system with angled freezes and ultrasound monitoring appears to be feasible and safe given our preliminary data.

Extirpated uterine endometrial cryoablation with ultrasound visualization

STUDY OBJECTIVE

To determine the efficacy of cryoablation of the uterus monitored by ultrasound.

DESIGN

Observational research (Canadian Task Force classification II-2).

SETTING

Clinic laboratory.

SUBJECTS

Eight uteri obtained after hysterectomy.

INTERVENTION

The uteri were subjected to freeze and thaw cycles in a 37 inverted exclamation markC water bath. Ultrasound was used to monitor the advancing ice front and ice ball diameter.

MEASUREMENTS AND MAIN RESULTS

Specimens were sectioned and stained with tetrazolium red to determine the region of nonviable tissue. The maximum average ice ball diameter as measured by ultrasound was 33.2 mm (range 29.1-35.4 mm). The average maximum diameter of nonviable tissue region was 24 mm (range 21.4-28.4 mm), with depth of tissue destruction ranging from 6 to 12 mm.

CONCLUSION

Cryosurgery at temperatures below -90 inverted exclamation mark C achieves excellent destruction of uterine tissue and complete destruction of endometrium. Ultrasound can be used to monitor freezing.