Uterine endometrial thermal balloon therapy for the treatment of menorrhagia: long-term multicentre follow-up study

Transcription

1 Human Reproduction Vol.18, No.5 pp. 1082±1087, 2003 DOI: /humrep/deg206 Uterine endometrial thermal balloon therapy for the treatment of menorrhagia: long-term multicentre follow-up study Nazar N.Amso 1,11, Herve Fernandez 2, George Vilos 3, Claude Fortin 4, Peter McFaul 5, Monika Schaffer 6, P.F.M.Van der Heijden 7, Marlies Y.Bongers 8, Barry Sanders 9 and Bernard Blanc 10 1 Department of Obstetrics and Gynaecology, University of Wales College of Medicine and the University Hospital of Wales, Cardiff CF14 4XN, UK, 2 H. A. BeÂcleÁre, Clamart, France, 3 St Joseph's Health Centre, London, Canada, 4 Clin MeÂd. Chateauguay, Canada, 5 Belfast City Hospital, Belfast, UK, 6 University Clinic Obstetrics and Gynaecology, Graz, Austria, 7 Twenteborg H., Almelo, The Netherlands, 8 St Joseph's Hospital, Veldhoven, The Netherlands, 9 University of British Columbia, Vancouver, Canada and 10 HoÃpital Conception, Marseilles, France 11 To whom correspondence should be addressed. amsonn@cardiff.ac.uk BACKGROUND: Initial reports from observational and randomized trials of uterine endometrial thermal balloon therapy (UBT) suggested good results as judged by return to eumenorrhoea or less and patient satisfaction. Longterm follow-up data remained limited by the small numbers of patients and duration of follow-up. We present longterm (4±6 years) follow-up data from a cohort of women previously treated with UBT for menorrhagia. METHODS: Of the 260 questionnaires sent to women eligible for long-term follow-up from 10 centres, 188 (72%) replies were received. The primary outcome measure was avoidance of hysterectomy. RESULTS: In women who responded to the questionnaire, 25 had undergone hysterectomy and 21 had had repeat ablation. At 4±6 years after UBT, the probability of avoiding hysterectomy was 86% of all women, and of avoiding re-ablation was 88% of nonhysterectomized women. Overall, the probability of avoiding any surgery was 75%. Women with an axial or retroverted uterus were at greater risk of hysterectomy or re-ablation. Among the participants, 47% of the non-hysterectomized women were amenorrhoeic, 30% were hypomenorrhoeic, 13.6% were eumenorrhoeic and 8.5% had heavy periods. CONCLUSIONS: This is the rst long-term follow-up report of a second-generation endometrial ablation procedure and con rms our initial experience. The high rate of hysterectomy avoidance over 5 years or more is very encouraging for this technology. Key words: endometrial thermal balloon therapy/hysterectomy/long-term follow-up/menorrhagia/ubt Introduction Uterine endometrial thermal balloon therapy (UBT) (ThermaChoice â ; Gynecare, a division of Ethicon, Somerville, NJ, USA), one of the earliest second-generation endometrial ablation techniques, was originally introduced by Neuwirth in 1994 (Neuwirth et al., 1994). Early reports (Singer et al., 1994; Vilos et al., 1997) were encouraging and led to a large multicentre observational study (Amso et al., 1998) and a multicentre randomized comparison between UBT and rollerball ablation (Meyer et al., 1998). The observational study and others comparing UBT with established rst generation ablation treatments such as rollerball (Meyer et al., 1998) and trans-cervical resection of the endometrium (TCRE) (Gervaise et al., 1999; Bongers et al., 2000) reported success in reducing menstrual loss and outcomes comparable with rstgeneration ablation techniques. This led to rapid acceptance and widespread use of UBT. More than of these procedures have been performed worldwide in the relatively short period of time since their introduction into clinical practice in 1995 (A.Beveridge, personal communication). UBT is less traumatic than hysterectomy and rst-generation endometrial ablation techniques, and is associated with less post-operative morbidity and a shorter recovery period, and can potentially be performed as day surgery with or without general anaesthesia. In the UK, menorrhagia affects about 22% of premenopausal women over the age of 35 years, and 5% of women aged 30±49 years consult their general practitioners (GPs) with heavy bleeding each year. First-line therapy is usually medication prescribed by GPs, but should these be ineffective, further treatment is necessary. Consideration of surgical interventions for menorrhagia accounts for some 12% of NHS gynaecology referrals (Sculpher et al., 1996). Unlike hysterectomy, a substantial proportion of women who undergo endometrial 1082 ã European Society of Human Reproduction and Embryology

2 Long term follow-up after uterine balloon ablation ablation will continue to menstruate, some with persistent or recurrent menorrhagia necessitating further surgery. Recent reports assessed the rate of further surgery in women who were treated with UBT in comparison with rollerball ablation or TCRE, but the follow-up period was relatively short, 2 and 3 years respectively (Bongers et al., 2000; Loffer, 2001). We report the results of a study in which a cohort of women complaining of menorrhagia and who underwent UBT were followed up for 4±6 years. The primary outcome measure was avoidance of hysterectomy. Secondary outcome measures included: (i) need for other surgical interventions e.g. TCRE, rollerball or repeat balloon ablation; (ii) impact of patient- and treatment-dependant variables on avoidance of hysterectomy; and (iii) current bleeding pattern in women who had not undergone hysterectomy. Materials and methods Study patients The group of patients treated with UBT and analysed for long-term follow-up was selected from the clinical study of balloon endometrial ablation system for the treatment of excessive uterine bleeding, which has been reported previously (Amso et al., 1998). Inclusion, exclusion criteria and data collection for the original study were as described previously (Amso et al., 1998). In summary, all women had severe menorrhagia as evidenced by their mean pad counts and subjective assessment of their bleeding, had failed or were unwilling to continue with medical therapy, had completed their family and were suitable for either ablation or hysterectomy. Women were excluded if there was a pathology distorting the uterine cavity, atypical endometrial hyperplasia, suspected genital tract infection or malignancy, uterine cavity depth >12 cm or previous endometrial ablation. Ten centres participated in the current study and, where necessary, ethical approval was obtained. Patients were eligible for inclusion in the study if: (i) they were treated by UBT between June 1994 and August 1996; (ii) the starting balloon pressure gradient was >150 mmhg; (iii) they were not taking hormone replacement therapy (HRT) in the rst year as part of another study; (iv) the 12-month follow-up (short-term) data for the original study were complete; and (v) they agreed to sign an informed consent form for the study. Patients were excluded from this study if: (i) they were treated by UBT with a starting gradient pressure of <150 mmhg; (ii) they were treated outside the clinical study protocol outlined above; (iii) the data recording of the 12-month follow-up was not complete; and (iv) they did not agree to take part or sign the patient informed consent form. As a result of the above criteria, 260 women from 10 participating centres were eligible for inclusion in the study. Two centres (41 eligible patients) did not take part in this study. Surgery Details of treatment protocol, technique and typical post-operative course have been described previously (Amso et al., 1998). In summary, the balloon was checked before insertion into the uterus and was lled with a variable volume of 5% dextrose water until a mean starting pressure of mmhg was achieved. The treatment cycle commenced when the uid temperature reached C and continued for 8 min. The controller unit continuously monitors, displays and controls pre-set balloon pressure, temperature and duration of treatment. At the conclusion of the treatment, the balloon was emptied, removed and checked again for any leaks. Follow-up The 10 investigators participating in this study were provided with a list of their patients from the 260 eligible women who met the protocol's selection criteria. The patients were mailed a study questionnaire asking them about their current menstrual history (days and severity of spotting or bleedingðlight, equivalent to normal loss, or heavy) and, where applicable the date of cessation of their periods and any adverse events or disease since their rst balloon ablation. They were also asked about current gynaecological problems, medication including HRT and whether they continued to bleed for some time after the ablation and then stopped (natural amenorrhoea) or their period stopped soon after the ablation (non-natural amenorrhoea). If further surgery (hysterectomy or repeat ablation) had taken place, the women were asked to give the date of the operation. In one centre, the ethics committee requested that the women's own GPs were contacted rst for con rmation of the contemporaneous addresses of the women and whether they were still registered with their GPs before mailing the questionnaires. If a woman did not respond within the rst 3±4 weeks, another questionnaire was mailed with a stamped, addressed envelope. Statistical analysis As we had anticipated that a proportion of women are lost to follow-up or would not respond to our questionnaire (nonparticipants group), it was essential to establish whether there was a signi cant risk of bias in the group who responded and hence for whom long-term follow-up data were available (participants group). To that effect, we compared the baseline and short-term follow-up characteristics, available from the original database, of the participants group and the non-participants group to ensure that they were comparable. Nine variables were selected for this comparison. Four were patient dependent (age at the time of the initial ablation, dysmenorrhoea score before and after treatment, uterine position, and depth of uterine cavity); three were intervention dependent (volume of uid in balloon, starting pressure and treatment duration); and two were short-term outcome measurements (initial result and hysterectomy after balloon ablation). The level of signi cance adopted was de ned using the Bonferroni method. This approach can be approximated by dividing the level of signi cance (a = 5%) by the number of variables tested (corrected a = 5/n, i.e. 5/9 = 0.555%). The Shapiro±Wilk test was used to test the hypothesis of normality of the two population groups (participants and non-participants). This was followed by a comparison of the means of these groups using Student's t-test, if the sample variances were homogenous. All statistical tests were two-tailed. A non-parametric test such as Mann±Whitney U-test was applied whenever parametric tests where not applicable. For descriptive variables in a contingency table, Pearson c 2 - and M-L c 2 -tests were employed to test the homogeneity of distribution. Relevant variables from the respondents to the questionnaires were analysed in accordance with appropriate statistical methods, and type 1 error (a) at 5% was accepted taking into account multiple testing. Life-table analysis using the actuarial method (Greenwood, 1926; Cox and Oaks, 1984) with 3 monthly intervals (quarters) was used to determine the risk of treatment failure after surgery, the primary endpoint being the time when hysterectomy was performed. The shortterm outcome data for the non-participants group were included in the calculation of the life-table analysis up to the point of their last contact. The same approach was adopted for repeat ablation or when calculating the probability of becoming amenorrhoeic. 1083

3 N.N.Amso et al. Table I. Comparison of participants group with non-participants using nine predetermined clinical variables Variable Participants Non-participants P-value Patient-dependent variables Patients' age (years) at time of initial ablation 40.6 (66.6) 39 (65.7) NS Dysmenorrhoea score a before initial ablation (%) 30, 31, 25, 14 8, 49, 22, at short-term follow-up (%) 59, 27, 9, 5 51, 38, 7, 4 NS Uterine position anteverted, axial, retroverted (%) 60, 23, 17 66, 18, 16 NS Uterine cavity depth (cm) preoperatively 8.63 (61.3) 8.07 (61.1) Intervention-dependent variables Volume of 5% dextrose (ml) used in balloon (67) (66.6) NS Starting balloon pressure (mmhg) (69.6) (66.7) NS Treatment duration (min) 8.84 (62.2) 8.22 (61.1) NS Short-term outcome measure variables Initial result b 2.14 (61.2) 2.10 (61.2) NS Hysterectomy during the short-term follow-up after thermachoice ablation (%) NS a Percentage of women with dysmenorrhoea in each category (none, mild, moderate, severe). b Amenorrhoea = 0; spotting = 1; hypomenorrhoea = 2; eumenorrhoea = 3; menorrhagia = 4 (Amso et al., 1998). NS = not signi cant. Results Of the 260 questionnaires sent to patients eligible for long-term follow-up, 188 replies were received (72%). One of the participants had incomplete information and was excluded from the hysterectomy and menstrual status life-table analysis. The non-participants group was divided equally between those who were lost to follow-up and those who did not reply to our questionnaire. One patient had died from an unrelated cause. Of the 187 participants who were entered in the life-table analyses, the time elapsed between the initial UBT and their response to the questionnaire was between 4 and 5 years in 38 patients, between 5 and 6 years in 122 patients, and between 6 and 7 years in 27 patients. Table I shows comparison of the participants and nonparticipants groups for four patient-dependent variables, three intervention-dependent variables and two short-term outcome variables. Signi cant difference was reported for the depth of the uterine cavity and the dysmenorrhoea score before, but not after, the treatment. The mean depth of the uterine cavity in the participants group exceeded by 0.56 cm that of the nonparticipants group. This variable is of doubtful clinical relevance and when tested by logistic regression model was found to have little or no clinical impact on the risk of hysterectomy. More non-participants had dysmenorrhoea of any severity before treatment (P < ). However, there was no signi cant difference between the two groups in the posttreatment dysmenorrhoea scores at the short-term follow-up contact (P = 0.463). According to this information, analysis of the long-term UBT outcome based only on the participants group was appropriate and hence, any systematic selection bias was unlikely. Current bleeding pattern The bleeding pattern of the participants varied from none (amenorrhoea) to light, normal or heavy. Of the 162 women 1084 Table II. Current bleeding pattern in participants who had not undergone hysterectomy and uterine position at the initial ablation Current bleeding a Uterine position b Anteverted Axial Retroverted Amenorrhoea Hypomenorrhoea Eumenorrhoea Menorrhagia Total a The current bleeding pattern of two patients, one with anteverted uterus and one with retroverted uterus, were not known b The uterine positions of three women, one in each of the amenorrhoea, hypomenorrhoea and eumenorrhoea groups, were not known. who had not had a hysterectomy, 76 (46.9%) were amenorrhoeic, 48 (30%) had light bleeding, 22 (13.6%) had normal periods and 14 (8.5%) had heavy bleeding. The bleeding pattern was not ascertainable in two patients (1%). Twenty of 76 women became amenorrhoeic within 3 months, while the overall median time to amenorrhoea was 4.6 quarters. In those who continued to bleed, the mean duration of bleeding was 3.8 days for the light bleeders, 4.6 days for the normal menses group and 9 days for the continuing menorrhagia group. The intensity of current bleeding in non-hysterectomized women appeared to be affected by uterine position at the time of initial surgery. A total of 16% (4/25) of women with a retroverted uterus complained of heavy bleeding compared with 2.8% (1/36) for axial uterus and 9.4% (9/96) for those with an anteverted uterus. Table II depicts the current distribution of bleeding pattern against the uterine position. In women who had undergone hysterectomy, the indications and the menstrual pattern at the time of surgery are outlined below. In women who had one ablation only and had not undergone hysterectomy (n = 141), 63 (45%) had no periods, 44 (31%) had light bleeding, 21 (15%) had normal menses and 12 (8.5%)

4 Long term follow-up after uterine balloon ablation Figure 1. Probability of not having a re-ablation, hysterectomy or both, and uterine position. Table III. Patient and treatment-dependent variables and their impact on avoidance of hysterectomy (successful outcome) in the participants group Variable No hysterectomy Hysterectomy P-value Patient-dependent variables Patients' age (years) at time of initial ablation 41 (66.7) 38.2 (65.3) NS Dysmenorrhoea score a before initial ablation (%) 32, 33, 23, 12 20, 20, 36, 24 NS at short-term follow-up (%) 62, 28, 7, 3 37, 21, 25, 17 < Uterine position anteverted, axial, retroverted (%) 61, 23, 16 52, 24, 24 < Uterine cavity depth preoperatively (cm) 8.62 (61.2) 8.72 (61.8) NS Intervention-dependent variables Starting balloon pressure (mmhg) 170 (69) 168 (612) NS Pressure drop (starting ± end pressure) 33.8 (622) 36.5 (629) NS a Dysmenorrhoea score (none, mild, moderate, severe). NS, not signi cant. had heavy periods. Of interest, 30 participants were taking HRT at the time of follow-up, 22 of whom were still amenorrhoeic, ve had light periods, only one had heavy periods, and in one patient the severity of menstrual loss was not known. The outcome in those who had repeat ablation (n = 21) was as follows; 13 (62%) became amenorrhoeic, four (19%) had light bleeding, one (5%) had normal menses and two (10%) continued to have heavy periods. Further surgery In the participants group, 25 women (13.3%) underwent hysterectomy and 21 (11.2%) had a second ablation during the follow-up period. The most common indication for hysterectomy was continued menorrhagia (n = 20). Other indications included broids (n = 2) and bleeding with unclear reason (n = 1). None had cancer as an indication. In two women the indications for hysterectomy were not known. The largest proportion of women requiring hysterectomy [18.8% (6/32)], was those with a retroverted uterus, followed by those with an axial uterus [14% (6/42)] and the least affected [11.7% (13/ 111)] were women with an anteverted uterus. None of the women who had repeat ablation underwent hysterectomy. Of the 21 repeat ablations among the participants, seven were for women who had spotting only, 11 were carried out in women with light periods and three in women who had a normal menstrual pattern after their initial procedure. Seven repeat ablations were carried out in each of the uterine position group, hence the proportion of repeat ablations was highest [27% (7/26)] in the retroverted position, compared with 19% (7/36) in the axial uterine group and 7% (7/97) in the anteverted group. Of those who had a second ablation, 13 women were amenorrhoeic at the time of the follow-up and seven continued to bleed, four of whom had light bleeding, one was bleeding normally, two continued to have heavy loss, and 1085

5 N.N.Amso et al. Figure 2. Life-table analysis of non-hysterectomized women becoming amenorrhoeic during the study. in one the severity of bleeding was unknown. The impact of uterine position on the probability of not having re-ablation in non-hysterectomized women was 77% for the retroverted uterus group, 83% for axial position and 94% for women with anteverted uterus. The impact of patient- and treatment-dependent variables on achieving a successful outcome (i.e. avoidance of hysterectomy) in the participants group is depicted in Table III. There was no statistical relationship between the age at initial procedure, pretreatment dysmenorrhea score and balloon pressure drop during the operation between those who had a hysterectomy and those who remained hysterectomy free. However, there was a signi cant difference in the posttreatment dysmenorrhoea score, with more frequent dysmenorrhoea among those who underwent hysterectomy (P < ). There was no signi cant relationship between uterine position and post treatment dysmenorrhoea score (P = 0.73). Statistical analysis using a c 2 -test indicated that there was most likely a statistical relationship between uterine position and outcome. However, it is essential to remember that the design of this study did not enable us to conclude that there is a relationship between cause and effect. In the non-participants group (n = 72), information available from the short-term follow-up indicated that seven women had undergone hysterectomy up to the point of last contact. No further long-term follow-up information was available. Life-table analysis At 4±6 years after the rst endometrial ablation, the probability of avoiding hysterectomy was 86% of all women [95% con dence interval (CI) 81±90.5%]. Similarly, in women who had not had hysterectomy, the probability of avoiding reablation was 88% (95% CI 83.4±92.8%). The overall probability of avoiding any form of surgery (hysterectomy or reablation) was 75% of all women (95% CI 69.4±81.2%) (Figure 1). The probability of avoiding further surgery (hysterectomy or ablation) varied according to uterine position and was the lowest in the retroverted uterus group (61%), increasing to 69% for the axial position, and was highest (80%) in women with an anteverted uterus (Figure 1). At 4±6 years follow-up, the probability of amenorrhoea in women who had not had hysterectomy was 52.1% (95% CI 43.1±52.7%) (Figure 2). Discussion In this study, 86% of women undergoing UBT did not require hysterectomy and 75% did not have any further surgery during a follow-up period of 4±6 years (median quarters, 5.2 years; mean quarters, 5.2 years). Our study is the rst long-term follow-up (>5 years) report of a second-generation endometrial ablation technique with hysterectomy as its primary end-point. Gervaise et al. (1999) reported a cumulative 3-year success rate, de ned as eumenorrhoea or less, to be 83% for UBT and 76% for endometrial resection. Two-year (Grainger et al., 2000) and 3-year (Loffer, 2001) follow-up data of a randomized controlled study comparing UBT with rollerball ablation (Meyer et al., 1998) reported similar rates. At 3 years, the percentages of women who reported no, reduced or normal menstrual loss were 93 and 94% respectively. Success was de ned as the percentage of patients with normal or no bleeding at 3 years and without hysterectomy or repeat ablation throughout the 3 years of follow-up (Loffer, 2001). During the 3 years, 7% (8/114) of the UBT group and 14% (14/ 99) of the rollerball group underwent hysterectomy, although the overall success rates were similar at 86 and 82% respectively (Loffer, 2001). In the study by Bongers et al. (2000), the cumulative re-intervention rate for the UBT group was 13% compared with 26% for the TCRE group. The above outcomes may appear better than those reported in this study. We observed that the rate of treatment failures reached a plateau between the fourth and fth years, and hence, it is possible that long-term results of other studies will closely resemble our experience. Earlier reservations concerning success rates of the secondgeneration devices stipulated that techniques performed under direct vision are more likely to treat all endometrial areas (O'Connor and Magos, 1996). The probability of not having hysterectomy 5 years after initial ablation was 91% with conventional endometrial resection (O'Connor and Magos, 1996) and 79% following endometrial laser ablation (Phillips et al., 1998). Similarly, the probability of not having any surgery in these two studies was 80 and 75% respectively. A randomized trial of endometrial ablation versus hysterectomy for the treatment of dysfunctional uterine bleeding reported the probability of further surgical treatment by any method after 4 years at 36% and by hysterectomy at 24% in women randomized to ablation (Aberdeen Endometrial Ablation Trials Group, 1999). A randomized study between another second generation device, microwave endometrial ablation (MEA), and TCRE reported that both techniques achieved high satisfaction and acceptability rates and both improved quality of life after 1 year (Cooper et al., 1999). The same authors reported that at 2 years follow-up, the two modalities continued to show highly signi cant reduction in bleeding and pain scores, but signi cantly more women were satis ed after MEA, and with its impact on menstrual loss, than TCRE (Bain et al., 2002). Hysterectomy rates were equally similar between the two groups (11.6 and 12.7%, respectively). In a previous report a number of factors were found to be associated with improved menstrual loss after treatment (Amso et al., 1998). In that study, with the exception of uterine 1086

6 Long term follow-up after uterine balloon ablation position and post ablation dysmenorrhoea score at short-term follow-up, no other patient or treatment-dependant variable was found to in uence the outcome. The statistical independence of uterine position and post-treatment dysmenorrhoea score indicate that each of them may independently in uence the long-term outcome. It is likely that the position of the heater element within the uterine cavity, especially in women with retroverted uteri, has a signi cant impact on outcome as judged by menstrual ow or the need for further surgery (Watermeyer and Amso, 2002). The choice between hysterectomy or repeat ablation may be determined by the perceived severity of symptoms and their impact on women's life-style and expectations balanced by their desire to avoid major surgery. In women who became amenorrhoeic it was dif cult to exclude natural menopause without endocrine studies. At the time of follow-up, 30 women were receiving HRT for peri- or post-menopausal symptoms, yet only seven women were menstruating. The nature of the HRT preparation was not known in all women, hence it was not possible to determine its relative contribution to the menstrual status. This study was not designed to evaluate the economic differences between UBT and hysterectomy. Studies that compared the costs of TCRE with hysterectomy reported that for patients with abnormal uterine bleeding treated with TCRE, there was a signi cantly shorter hospital stay and quicker return to normal daily activity (Sculpher et al., 1996; Hidlebaugh, 2000). Data from a randomized clinical trial indicated that at 2 years follow-up, TCRE costs (including cost of reintervention) were only 71% of the costs of abdominal hysterectomy (Sculpher, 1998). The role of any surgical procedure must balance its bene ts and risks. The surgical nature of thermal balloon ablation, even though it is associated with minimal complications, means that medical therapy will most likely remain the rst choice. However, a recent randomized study suggested that immediate TCRE is more effective than medical treatment and does not result in an increase in hysterectomies (Cooper et al., 2001). Additionally, clinicians must be aware that there is an as yet undetermined risk of this surgery on the early warning signs of endometrial hyperplasia or cancer in menopausal women who have previously undergone ablation. However, the high rate of avoidance of hysterectomy over a long period of time means that UBT offers women who are reluctant to undergo hysterectomy the dual advantages of relatively conservative surgery and freedom from prolonged medical therapy. Acknowledgements The authors wish to thank Dr Frederic Daoud, Medalliance SARL, France, for his contribution to data collation and statistical analysis. We also wish to thank Gynecare, a division of Ethicon, a Johnson and Johnson Co., for their support of this study. References Aberdeen Endometrial Ablation Trials Group. (1999) A randomised trial of endometrial ablation versus hysterectomy for the treatment of dysfunctional uterine bleeding: outcome at four years. Br. J. Obstet. Gynaecol., 106, 360±366. Amso, N.N., Stabinsky, S.A., McFaul, P., Blanc, B., Pendley, L. and Neuwirth, R. (1998) Uterine thermal balloon therapy for the treatment of menorrhagia: the rst 300 patients from a multi-centre study. International collaborative uterine thermal balloon working group. Br. J. Obstet. Gynaecol., 105, 517±523. Bain, C., Cooper, K.G. and Parkin, D.E. (2002) Microwave endometrial ablation versus endometrial resection: A randomised controlled trial. Obstet. Gynecol., 99, 983±987. Bongers, M.Y., Mol, B.W.J., Dijkhuizen, F.P.H. and BroÈlmann, H.A.M. (2000) Is balloon ablation as effective as endometrial electroresection in the the treatment of menorrhagia? J. Laparoendosc. Adv. Surg. Tech., 10, 85±92. Cooper, K.G., Bain, C. and Parkin, D.E. (1999) Comparison of microwave endometrial ablation and transcervical resection of the endometrium for treatment of heavy menstrual loss: a randomised trial. Lancet, 354, 1859±1863. Cooper, K.G., Jack, S.A., Parkin, D.E. and Grant, A.M. (2001) Five-year follow-up of women randomised to medical management or transcervical resection of the endometrium for heavy menstrual loss: clinical and quality of life outcomes. Br. J. Obstet. Gynaecol., 108, 1222±1228. Cox, R.D. and Oaks, D. (1984) Analysis of survival data. Chapman and Hall, London, UK. Gervaise, A., Fernandez, H., Capella-Allouc, S., Taylor, S., La Vieille, S., Hamou, J. and Gomel, V. (1999) Thermal balloon ablation versus endometrial resection for the treatment of abnormal uterine bleeding. Hum. Reprod., 14, 2743±2747. Grainger, D.A., Tjaden, B.L., Rowland, C. and Meyer, W.R. (2000) Thermal balloon and rollerball ablation to treat menorrhagia: two-year results of a multicentre, prospective, randomized, clinical trial. J. Am. Assoc. Gynecol. Laparosc., 7, 175±179. Greenwood, M.A. (1926) Report on the natural duration of cancer, appendix 1: the `errors of sampling' of the survivorship tables. Reports on public health and medical subjects. Number 33, App. 1. Stationery Of ce, London, UK. Hidlebaugh, D.A. (2000) Cost and quality-of-life issues with different surgical therapies for the treatment of abnormal uterine bleeding. Obstet. Gynecol. Clin. North. Am., 27, 451±465. Loffer, F.D. (2001) Three-year comparison of thermal balloon and rollerball ablation in treatment of menorrhagia. J. Am. Assoc. Gynecol. Laparosc., 8, 48±54. Meyer, W.R., Walsh, B.W., Grainger, D.A., Peacock, L.M., Loffer, F.D. and Steege, J.F. (1998) Thermal balloon and rollerball ablation to treat menorrhagia: a multicenter comparison. Obstet. Gynecol., 92, 98±103. Neuwirth, R.S., Duran, A.A., Singer, A., MacDonald, R. and Bolduc, L. (1994) The endometrial ablator: A new instrument. Obstet. Gynecol., 83, 792±796. O'Connor, H. and Magos, A. (1996) Endometrial resection for the treatment of menorrhagia. N. Engl. J. Med., 335, 151±156. Phillips, G., Chien P.F.W. and Garry. R. (1998) Risk of hysterectomy after 1000 consecutive endometrial laser ablations. Br. J. Obstet. Gynecol., 105, 897±903. Sculpher, M. (1998) The cost-effectiveness of preference-based treatment allocation: the case of hysterectomy versus endometrial resection in the treatment of menorrhagia. Health Econ., 7, 129±142. Sculpher, M.J., Dwyer, N., Byford, S. and Stirrat, G.M. (1996) Randomized trial comparing hysterectomy and transcervical endometrial resection: effect on health related quality of life and costs two years after surgery. Br. J. Obstet. Gynaecol., 103, 142±149. Singer, A., Almanza, R., Gutierrez, A., Haber, G., Bolduc, C.R. and Neuwirth, R., (1994) Preliminary clinical experience with a thermal balloon endometrial ablation method to treat menorrhagia. Obstet. Gynecol., 84, 732±734. Vilos, G.A., Fortin, C.A., Sanders, B.A., Pendley, L. and Stabinsky, S.A. (1997) Clinical trial of the Uterine Thermal Balloon for treatment of menorrhagia. J. Am. Assoc. Gynecol. Laparosc., 4, 559±565. Watermeyer, S.R. and Amso, N.N. (2002) Observational case reports of intra and post operative ultrasound monitoring of uterine balloon ablation. J. Obstet. Gynecol., 22, 432±435. Submitted on March 8, 2002; resubmitted on October 28, 2002; accepted on January 16,