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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, St. Joseph Hospital, Veldhoven, The Netherlands; and Department of Obstetrics and Gynecology, University Hospital, Utrecht, The Netherlands.
Address reprint requests to: M. Y. Bongers, MD, St. Joseph Hospital, Department of Obstetrics and Gynecology, P.O. Box 7777, 5500 MB Veldhoven, The Netherlands; E-mail: my.bongers{at}iae.nl.
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ABSTRACT |
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METHODS: This is a prospective study on patients referred for menorrhagia and treated with hot fluid thermal balloon ablation. Potential prognostic factors for assessing the success of treatment were recorded. Success was defined as patient satisfaction and no subsequent hysterectomy at 2-year follow-up.
RESULTS: A total of 130 women were included in the final analysis. The cumulative rate of patients undergoing a hysterectomy after 2 years was 12%. After 2 years, 81% of the remaining patients were satisfied with the results of the treatment. Predictive factors for adverse outcome were a retroverted uterus (hazard rate ratio 3.3, 95% confidence interval [CI] 1.2, 8.6), pretreatment endometrial thickness of at least 4 mm (hazard rate ratio 3.6, 95% CI 1.3, 11), and the duration of menstruation (hazard rate ratio 1.2, 95% CI 1.0, 1.3, per day in excess of 9 days). The risk of an adverse outcome declined steadily with increasing age (hazard rate ratio 0.86, 95% CI 0.77, 0.96 per year over 42 years of age). Uterine depth and dysmenorrhea were not predictive factors, which significantly affected outcome.
CONCLUSION: Young age, retroverted uterus, endometrial thickness of at least 4 mm, and prolonged duration of menstruation were associated with an increased risk of treatment failure. Uterine depth and dysmenorrhea had limited impact on the effectiveness of balloon ablation.
Several transcervical endometrial ablation methods have been used for the treatment of menorrhagia. Transcervical resection of the endometrium, endometrial laser ablation, and hot fluid balloon ablation have all shown to be effective alternatives to hysterectomy.1–6 As each treatment has its own potential advantages and disadvantages, it is difficult to choose and advise the best individual treatment for excessive menstrual bleeding. Hysterectomy guarantees amenorrhea in all women, but is costly and has a significant impact on health-related quality of life immediately after surgery.7,8
Hot fluid balloon ablation reduces postoperative disability when compared with hysterectomy. In addition, this treatment is potentially less costly.9 However, patient satisfaction with the result of ablation is often less than that after hysterectomy. There is also a chance that a subsequent hysterectomy will be required. Most women who choose endometrial ablation rather than hysterectomy as therapy for menorrhagia are prepared to undergo this treatment even if the chances of success are somewhat limited.10 Despite this willingness to accept a potential risk of treatment failure, counseling of women with menorrhagia could be improved by predicting the probability of success of balloon ablation in each particular case.
The purpose of the present study was to assess potential prognostic factors determining the success of hot fluid balloon ablation in women with menorrhagia.
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MATERIALS AND METHODS |
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Premenopausal women with menorrhagia not responding to medical treatment were informed about possible treatments. The potential advantages and disadvantages of endometrial ablation with hot fluid balloon, hysterectomy, and also the effects of withholding treatment, were discussed with each patient. Menorrhagia had to be objectified by a pictorial chart and was defined as more than 150 points.11 All patients who opted for hot fluid balloon ablation were included in the study. Patients had to be over 30 years old. Patients with inter-menstrual bleeding or metrorrhagia were not included. Women who used oral contraceptives, antiprostaglandins, gonadotropin-releasing hormone agonists, or anti-fibrinolytic agents in the previous 3 months before the ablation were also not included in the study. Patients wishing to preserve future fertility, as well as those with active or recurrent chronic pelvic inflammatory disease and cervical dysplasia were also not included in the study. To determine whether the patient was eligible for hot fluid balloon ablation, a hysteroscopy with endometrial biopsy was performed on all patients.
After patients’ inclusion in the study, aspects such as age, duration of menstruation (days), position of the uterus (anteversion or retroversion), and the presence or absence of dysmenorrhea were recorded. The position of the uterus was assessed by bimanual examination during the first visit to the outpatient clinic and confirmed during hysteroscopy. Dysmenorrhea was recorded as either present or absent.
Exclusion criteria for ablation were a uterine depth more than 11 cm, the presence of submucous fibroids or intrauterine polyps, malignancy of the uterus or cervix, and the presence of intrauterine adhesions.
Balloon ablation therapy was performed in the operating room under regional or general anesthesia. Analgesia with a nonsteroid anti-inflammatory drug was given several hours before treatment, and each patient received prophylactic antibiotics (Augmentin 2000/200 mg) just before the onset of the ablation. The procedure was begun with a transvaginal sonography to measure endometrial thickness just before treatment. Aspiration curettage using a 4-mm flexible curette was carried out to thin the endometrium. After measuring uterine depth, a balloon catheter (ThermaChoice, Gynecare, Somerville, NJ) was introduced in the uterine cavity. The balloon catheter was then filled with 5% glucose solution to a pressure of 180 mm Hg. A thermistor in the balloon was used to raise the temperature of the fluid to 87C (170 F) for a period of 8 or 16 minutes, whereas the pressure of the balloon was maintained at 170 mm Hg or higher. The patient was discharged the same day.
To evaluate whether doubling of the heating time would improve success rate of hot fluid balloon ablation, 63 patients were treated for 8 minutes and 67 patients for 16 minutes. There was no difference between these two groups at the 2-year follow-up, a result that has been published previously of the same patients.12 At the follow-up, it was recorded whether a hysterectomy had been performed. Standardized follow-up data on duration of menstruation and patient satisfaction were collected 3, 6, 12, and 24 months after surgery, during outpatient visits. Patient satisfaction was registered on a four-point scale (perfectly satisfactory, satisfactory, no treatment effect, unsatisfactory). Success was defined as patient satisfaction and no subsequent hysterectomy at 2-year follow-up.
The aim of the analysis was to relate potential prognostic factors available before the start of treatment to the occurrence of an adverse outcome. An adverse outcome was defined as a hysterectomy, a second ablation, or unsatisfactory treatment results—in other words, no improvement or a worsening of bleeding. Time to adverse outcome was censored when one of these events had not been observed by the end of follow-up. If the hot fluid balloon procedure could not be completed, the patient was excluded from the analysis. Two Kaplan-Meier curves were constructed—the first denoted the occurrence of hysterectomy and the second, the presence of unsatisfactory treatment results and/or the occurrence of hysterectomy.
For the continuous variables (age, duration of menstruation, endometrial thickness at sonography, and sound length), a spline function was incorporated. This was used to express the probability of an adverse outcome, as a function of a continuous variable, and was constructed using logistic regression analysis.13–15 Based on spline functions, continuous variables were redefined, taking into account the association between them and the occurrence of an adverse outcome (such as hysterectomy and/or unsatisfactory treatment results). Such a redefinition was not required for the dichotomous variables, dysmenorrhea and uterine position.
The relative hazard of an adverse outcome was calculated using Cox regression modeling.16 The hazard rate ratio expresses the relative chance of an adverse outcome in one group of patients as compared with another group. A hazard rate ratio of below 1 demonstrates the hazard rate in a group with a particular risk factor, as compared with a group without that particular factor. Firstly, the hazard rate ratio and 95% confidence intervals (CI) of each potential prognostic factor, plus the corresponding P value were calculated in a univariable analysis. Then, a multivariable analysis was performed. Cox regression is a technique that can be used here to evaluate the performance of multiple variables in a prognostic model. Selection of variables is usually performed with a significance level of 5%. However, the incorrect exclusion of a diagnostic factor would be more deleterious to the overall result than the inclusion of too many factors.17 Therefore, in this study, multivariable analysis included all variables with a P value < .30 in the univariable analysis.
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RESULTS |
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The median age of the patients was 42 years (range 30–56 years), the mean duration of menstruation before the start of treatment was 9.3 days, whereas dysmenorrhea was present in 52 patients (39%). The uterus was anteverted in 89 patients (69%), in midposition in 20 patients (15%), and retroverted in 21 patients (16%). The mean endometrial thickness by transvaginal sonography before treatment was 5.1 mm, and the mean uterine depth was 8.9 mm. At follow-up, 12 patients had undergone hysterectomy, and 11 were dissatisfied with the result. Kaplan-Meier curves showing time to hysterectomy and time to dissatisfaction with the treatment result are shown in Figure 1
. The cumulative rate of hysterectomy after 1 year was 9.5% and 12.5% for either dissatisfaction or having had hysterectomy, respectively. Two years after the balloon ablation, the respective rates were 12% and 19%.
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Figure 2 shows the risk of an adverse outcome as a function of age, duration of menstruation, endometrial thickness at sonography, and uterine depth. The risk of an adverse outcome declined steadily with advancing age. In contrast, this risk increased with duration of menstruation. The impact of uterine depth and endometrial thickness as observed at sonography was limited. The variables found in spline functions constructed for age, duration of menstruation, and uterine depth did not require redefinition for the Cox regression analysis. The variable endometrial thickness was dichotomized in a thickness of at least 4 mm or less than 4 mm.
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shows the results of the univariable Cox regression analysis. Advanced age reduced the risk of an adverse outcome (hazard rate ratio 0.93 per year, as patients become older), whereas the risk of an adverse outcome increased when the duration of menstruation before treatment was longer (hazard rate ratio 1.1 per day, as the menstruation was longer). Dysmenorrhea, a uterus in retroversion flexion, and an endometrial thickness of at least 4 mm were associated with an increased risk of an adverse outcome. Uterine depth was not associated with the risk of an adverse outcome.
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also shows the results of the multivariable Cox regression analysis. Uterine depth and midposition of the uterus were not incorporated in the multivariable analysis because the univariable analysis showed respective corresponding P values of .85 and .51. The hazard of an adverse outcome was reduced with advancing patient’s age (hazard rate ratio 0.86, 95% CI 0.77, 0.96 per year at over 42 years of age), whereas an increased duration of menstruation was associated with an increased risk (hazard rate ratio 1.2, 95% CI 1.0, 1.3 per day in excess of 9 days). A retroverted uterus and an endometrial thickness of at least 4 mm were associated with an increased risk of an adverse outcome with hazard rate ratios of 3.3 and 3.6, respectively. All these four associations were statistically significant. However, dysmenorrhea, associated with an increased risk in the univariable analysis, had limited impact on the multivariable analysis (hazard rate ratio 1.3, P = .51). |
DISCUSSION |
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With patients having a retroverted uterus, the risk of failure of the balloon therapy was increased three-fold. This may occur because the posterior wall of a uterus in retroversion will not have as much thermal injury as the posterior wall of an anteverted uterus. This issue remains a subject for future research. It was also established that a partial ablation does not always diminish the success rate.22 The balloon ablation procedures in this study were performed with a ThermaChoice I generator. A new balloon ablator (ThermaChoice II, Gynecare, Somerville, NJ) with an umpellar to circulate the fluid within the balloon has been developed and is available in the United States. The circulation of the fluid within the balloon may diminish the differences in thermal injury of the posterior wall and anterior wall of the uterus.
Thick endometrium prevents a deep intramural thermal effect and therefore limits damage of the basal layer. This may explain why thermal ablation was less effective in patients with an endometrium of at least 4 mm—a measurement that would appear to represent a threshold. Whether preoperative thinning of the endometrium with GnRH analogs will improve success rate of balloon ablation is still a matter of debate. Although Amso et al reported statistically higher rates of postprocedure amenorrhea in women who received depot GnRH agonist before balloon treatment,20 this did not improve treatment outcome. Treatment outcome was defined as no surgical intervention.
Older women often have better results from endometrial ablation than those who are younger.23 In addition, as follow-up time increases, some patients may become menopausal. We are not, however, aware of a trial in which the effect of FSH levels is systematically evaluated.
Duration of menstruation before treatment was associated with an increased risk of treatment failure. The pictorial chart produced by the patients before they entered the study was used to calculate the length of menstruation. A longer menstruation represents a more serious problem and is therefore probably more difficult to treat.
Recently, Gervaise et al21 reported on prognostic factors associated with failure of endometrial resection and thermal balloon ablation. In that study,21 a retroverted uterus was associated with failure of treatment (hazard rate ratio 3.9, 95% CI 1.2, 13) (
Bongers MY, Mol BWJ. Thermal balloon ablation versus endometrial resection for the treatment of abnormal uterine bleeding [letter]. Hum Reprod 2000;15:1424–5
In conclusion, this study confirms that hot fluid balloon endometrial ablation is an effective treatment for menorrhagia. Young age, prolonged duration of menstruation, thick endometrium, and a retroverted uterus are all associated with a statistically significant and clinically relevant increased probability of failure. These findings should be taken into account when counseling women with menorrhagia.
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Footnotes |
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Received September 17, 2001. Received in revised form January 30, 2002. Accepted February 21, 2002.
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REFERENCES |
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2. Bhattacharya S, Cameron IM, Parkin DE, Abramovich DR, Mollison J, Pinion SB et al. A pragmatic randomised comparison of transcervical resection of the endometrium with endometrial laser ablation for the treatment of menorrhagia. Br J Obstet Gynaecol 1997;104:601–7.[Medline]
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