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Obstetrics & Gynecology 1999;94:521-527
© 1999 by The American College of Obstetricians and Gynecologists
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ORIGINAL RESEARCH

Randomized Comparison of Vaporizing Electrode and Cutting Loop for Endometrial Ablation

PAOLO VERCELLINI, MD, SABINA OLDANI, MD, LARA YAYLAYAN, MD, BARBARA ZAINA, MD, OLGA DE GIORGI, MD and PIER GIORGIO CROSIGNANI, MD

From the Clinica Ostetrica e Ginecologica "Luigi Mangiagalli", University of Milano and Istituti Clinici di Perfezionamento, Milano, Italy.

Address reprint requests to: Paolo Vercellini, MD Clinica Ostetrica e Ginecologica "Luigi Mangiagalli" Universita di Milano Via Commenda 12-20122 Milano Italy


   Abstract
Top
Abstract
Materials and Methods
 Results
 Discussion
 References
 
Objective: To compare endometrial ablation using a vaporizing electrode with resection using a standard cutting loop, evaluating distension fluid absorption, operating time, and ease of procedure.

Methods: Premenopausal menorrhagic women with normal hysteroscopic and endometrial biopsy findings were allocated randomly to endometrial vaporization (n = 47) or resection (n = 44). Distension medium deficit, operating time, and degree of difficulty of the procedure were determined at surgery. Menstrual pattern of women in both groups was also assessed after 1-year follow-up.

Results: Mean ± standard deviation (SD) distension fluid deficit was 109 ± 126 mL in the vaporization and 367 ± 257 mL in the resection group (mean difference 258 mL; 95% confidence interval 175, 341 mL; P < .001, unpaired t test). Mean ± SD operating time was, respectively, 9.2 ± 3.1 minutes versus 10.7 ± 2.5 minutes. The surgeon classified intraoperative difficulties as none in 32, minimal in 11, moderate in four, and severe in none in the vaporization group, and 17, 14, seven, and six in the resection group. Menstrual pattern at 1 year in the former group was amenorrhea in 17 (36%) cases, hypomenorrhea or spotting in 20 (43%), normal flows in 10 (21%), and menorrhagia in none compared with, respectively, 21 (48%), 14 (32%), seven (16%), and two (5%) in the latter group.

Conclusion: Endometrial ablation with the vaporizing electrode limited fluid absorption compared with resection by the standard cutting loop. Long-term effects on uterine bleeding were similar.

Endometrial resection with a cutting loop is considered by many the standard reference technique for hysteroscopic treatment of abnormal uterine bleeding, but complications are frequent and a high level of surgical skill is necessary.1–6 In particular, excessive absorption of distension fluid through the sectioned myometrial veins remains a potentially severe problem.7,8 A spherical rollerball electrode that coagulates the tissues with immediate hemostatic vasoocclusion,9 which limits intravasation but is more time-consuming, might be suboptimal over the long-term, and excludes treatment of submucous myomas.10,11

A cylindrical, corrugated electrode or vaporizer (Vaportrode; Circon Acmi, Stamford, CT; Figure 1Go) has been developed that, due to its peculiar physical characteristics, should allow fast and radical ablation of endometrium and myomas. The bar electrode has three grooves that provide eight edges along which electrons concentrate, allowing immediate cell vaporization on contact. We showed in vivo that a vaporizing electrode produces furrows of similar depth to those of a standard cutting loop.12 However, the depth of coagulation beneath the ablated area by the electrode is significantly greater compared with the loop.12



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  		Figure 1. The cylindrical, corrugated, vaporizing electrode. The three grooves provide eight edges along which electrons concentrate. Reprinted with permission from Vercellini P, Oldani S, Milesi M, Rossi M, Carinelli S, Crosignani PG. Endometrial ablation with a vaporizing electrode. I. Evaluation of in vivo effects. Acta Obstet Gynecol Scand 1998;77:683–7. © 1998 Munksgaard International Publishers Ltd., Copenhagen, Denmark.[Medline]

 
Sealing myometrial vessels by thermal effect should influence fluid intravasation. The median amount of fluid deficit in a clinical pilot study on endometrial vaporization with a normal uterine cavity was only 50 mL.13 The technique has proven safe, rapid, and easy, and unlike rollerball ablation, allows treatment of submucous myomas.13,14 In a urologic study, transurethral vaporization of the prostate was more rapid and involved less bleeding and absorption of fluid than usual resection with the loop.15

The vaporizing electrode appears to offer advantages over the cutting loop for hysteroscopic treatment of menorrhagia, so we conducted a randomized controlled trial to evaluate the effects of those two methods of endometrial ablation in women with dysfunctional uterine bleeding. The primary aim was to determine whether absorption of distension fluid was reduced in women who had endometrial vaporization compared with those who had classic endometrial resection. We also compared the technical feasibility of the two procedures in terms of length, degree of difficulty, and complications of the operation. Menstrual patterns in the groups were compared 1 year after surgery.


   Materials and Methods
Top
Abstract
 Materials and Methods
Results
 Discussion
 References
 
We ran this open, parallel-group, randomized controlled trial in an academic department specializing in operative hysteroscopy. The trial protocol was approved by the ethics committee of the Istituti Clinici di Perfezionamento. Subjects gave written informed consent in compliance with the Helsinki Declaration.

Women 35 years or older referred to our tertiary care center for hysterectomy for menorrhagia were considered for recruitment. Excessive uterine bleeding was diagnosed by history, serum hemoglobin, hematocrit and iron levels, and a pictorial blood assessment chart devised by Higham et al16 to evaluate menstrual flow. A monthly score of 100 or higher on the chart is significantly associated with a uterine blood loss of over 80 mL measured by the alkaline hematin method.16 Before randomization, each subject completed a menstrual diary card for two consecutive menses and had a complete physical examination, transvaginal ultrasonography, diagnostic hysteroscopy, and endometrial biopsy. Eligible subjects had uterine volumes less than a 12-week pregnancy, no evidence of atypical hyperplasia at endometrial biopsy, no adnexal tumors on clinical and ultrasonographic examination, and normal uterine cavity at hysteroscopy. Women uncertain about future children were excluded. Other exclusion criteria were recent use of hormonal agents or drugs that might affect menstrual blood loss, intramural or subserous myomas of 3 cm or more diameter, and unstable general conditions due to acute bleeding episodes. A depot preparation of GnRH agonist triptorelin was used preoperatively for 2 months to promote endometrial thinning, reduce fluid absorption, and facilitate intrauterine surgical conditions.17,18

After general anesthesia in the operating room, eligible subjects were randomized 1:1 to endometrial ablation with vaporizing electrode or endometrial resection with cutting loop. Treatment was allocated by a computer-generated randomization sequence using serially numbered, opaque, sealed envelopes, which were kept with the original randomization list by the ward sister, and not available to attending physicians.

In all cases, a 25-French gauge rigid resectoscope (G25-ST-CFR; Circon Acmi) and 12° fore-oblique telescope (M3–12; Circon Acmi) were used, equipped with a cylindrical, 3-mm-wide, vaporizing electrode (VE-B; Circon Acmi) or with a standard right-angle cutting loop electrode (MLE-24-015; Circon Acmi). After insertion of the resectoscope, the uterine cavity was distended with a nonconductive, hypoosmolar solution of 2.7% sorbitol and 0.54% mannitol, instilled under manometric control, with a pressure of 100–120 mmHg generated by a pneumatic cuff for intrauterine irrigation and a vacuum of -30 to -40 mmHg applied for suction. Endometrial vaporization was done with pure cutting waveform current set at 200 watts power. The mucosa of the cornual areas was treated radially starting from the tubal ostia, withdrawing the electrode toward the surgeon at a speed of 1–1.5 cm/second, applying minimal pressure on the uterine wall. Vaporization was completed on the fundus and remaining cavity down to the isthmus. Resection was standard with cutting current set at 100 watts power. Treatment of cornual areas was completed with a 3-mm-diameter ball electrode and coagulating current set at 70 watts power.

To measure fluid deficit, a modification of the spring balance technique was adopted.19–20 A 3-liter irrigating solution plastic bag with a pressure cuff was connected to the resectoscope by a fluid line and then hung on a clock balance (range 0–5 kg). The weight of the primed complete infusion set was 3300–3400 g. The outflow port of the hysteroscopic equipment was connected to a usual surgical closed-suction unit that collects aspirated fluid in plastic bags inside cylindrical, transparent, rigid containers with graduated volume marks along their lengths. Plastic draping commonly used in delivery rooms was placed under the subject’s buttocks to funnel fluid escaping through the cervix into a calibrated pouch. Direct visual monitoring of the system allowed constant assessment of fluid balance during the procedure. To determine fluid input, residual weight indicated on the clock balance was subtracted from the initial reading before disconnecting the infusion bag from the resectoscope. The plastic bag of the suction unit and the cylindrical portion of the perineal draping were sealed and weighed together to measure fluid output. The difference between fluid input and output corresponds to the overall deficit.

Operating time was defined as the interval between the initial insertion and final removal of the instrument. After intervention, the surgeon classified the degree of difficulty of the procedure (based on ease and completeness of endometrial treatment and intracavitary bleeding) as none, minimal (same as routine), moderate (slightly more than usual), or severe (much more than usual). Intra- and postoperative complications were also recorded.

The women, aware of the technique used for endometrial ablation, had follow-up visits 1, 3, 6, 9, and 12 months after surgery, when gynecologic examinations were done, uterine bleeding histories and pictorial blood loss assessment charts were assessed, and adverse events were recorded. Serum hemoglobin, hematocrit, and iron levels were measured at baseline, 6, and 12 months. During the 12-month examination, subjects were asked to rate degree of satisfaction with their treatments on a five-level scale (very satisfied, satisfied, uncertain, dissatisfied, very dissatisfied). At the same time, a second-look diagnostic hysteroscopy with biopsy was offered to compare repair of the uterine cavity and assess presence, distribution, and histologic aspects of residual endometrium after the two surgical methods. Women were informed that the procedure was not likely to cause major modifications in management.

The sample was based on fluid absorption during endometrial ablation. According to our previous study,18 the standard deviation (SD) of the variable in women who had hysteroscopic resection after endometrial preparation with GnRH agonists was around 300 mL. A difference of 200 mL in fluid absorption between treatment groups was considered clinically relevant. To have an 80% chance of detecting such a difference at an overall significance level of 5%, about 40 subjects per study arm were required. Allowing for withdrawals, the aim was to recruit approximately 45 women per group. The statistical significance of differences in mean fluid absorption, operating time, and pictorial blood-loss assessment chart scores were analyzed by unpaired t test. The degrees of difficulty at intervention and satisfaction with treatment were compared by Fisher exact test. All statistical tests were two-sided. P < .05 was considered statistically significant. Confidence intervals (CIs) were calculated for some differences.


   Results
Top
Abstract
 Materials and Methods
 Results
Discussion
 References
 
One hundred thirty-four women evaluated for menorrhagia in an outpatient clinic between March 1996 and February 1997 were eligible, but 43 refused randomization (26 requested hysterectomy, nine requested endometrial resection with the cutting loop, and eight were lost to further contact). The remaining 91 subjects, aged 35–52 years, were allocated to endometrial vaporization (n = 47) or endometrial resection (n = 44). Baseline characteristics are shown in Table 1Go. Distribution of clinical variables was similar between groups. One woman in each study arm had previous tubal ligation.


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  		Table 1. Clinical Characteristics of Study Subjects
 
All hysteroscopic procedures were done by one surgeon (P.V.) without intraoperative complications. The mean distension medium deficit was 70% less in women who had endometrial vaporization than those with endometrial resection (Table 2Go), with a difference of 258 mL (95% CI 175, 341 mL). The amount of fluid absorbed was 500 mL or more in one woman (2%) in the vaporization group and 14 (32%) in the resection group, whereas no medium was absorbed in 16 (34%) and one (2%), respectively (Figure 2Go). The maximum deficit in the vaporization group was 600 mL in one woman, in the resection group it was 850 mL in four. None of the subjects developed symptoms or signs of fluid overload, or severe dilutional hyponatremia. Endometrial ablation was slightly faster than resection, with a mean difference of 1.5 minutes between techniques (95% CI 0.3, 2.7 [Table 2Go]). According to the surgeon’s assessment, endometrial vaporization was significantly easier than resection. There was an appreciable between-group difference in the percentage of women with no or minimal operating difficulties (91% in the experimental group and 70% in the control group; odds ratio 4.51, 95% CI 1.34, 15.15 [Table 2Go]). There was no correlation between degree of difficulty and time required to complete the procedure (data not shown). The postoperative courses of the women were uneventful, and all were discharged within 24 hours.


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  		Table 2. Results of Hysteroscopic Endometrial Ablation
 


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  		Figure 2. Distension medium deficit in women who had endometrial vaporization (closed circles) or endometrial resection (open circles). Horizontal bars indicate means.

 
The 12-month follow-up was completed by all subjects except one in the resection group, who was lost to follow-up after the 9-month visit, when she was still menorrhagic and very dissatisfied. She was included in the evaluation of menstrual pattern and patient satisfaction but not in pictorial blood loss scores because the final diaries were not available. Two subjects in the vaporization group and four in the resection group developed menopausal symptoms with elevated FSH serum levels. There was recurrent menorrhagia, defined as a monthly pictorial blood loss assessment chart score of 100 or higher, in two women in the resection arm (the one lost to follow-up and a second one who had a hysterectomy 6 months after the hysteroscopic procedure). Mean ± SD monthly bleeding scores fell from 282 ± 191 to 15 ± 24 at 12 months in the vaporization group, and from 270 ± 150 to 20 ± 42 in the resection group, without a statistically significant difference. Amenorrhea or hypomenorrhea was reported at 12 months by 37 of 47 vaporization women (79%) and 35 of 44 (80%) resection women (Table 3Go). Satisfaction with treatment was similarly high in both groups with 45 of 47 (96%) women satisfied or very satisfied after endometrial vaporization, compared with 41 of 44 (93%) after resection (Table 3Go). Systematic evaluation of subjects continued after the 12 months. After a mean follow-up of 26 months (range, 18–51), there were no significant variations in bleeding scores. In the vaporization group, one amenorrheic woman became hypomenorrheic, and one with normal flows became menorrhagic and was given GnRH agonist therapy. In the resection group, one previously amenorrheic woman reported normal flows. One woman in the vaporization group became dissatisfied, after being satisfied, due to pelvic pain associated with a microhematometra identified on ultrasonography.


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  		Table 3. Symptoms 12 Months After Surgery
 
Only 31 women who were amenorrheic (n = 11), hypomenorrheic (n = 13), or eumenorrheic (n = 7) agreed to have second-look hysteroscopy, 15 in the vaporization and 16 in the resection group. The uterine cavity was shrunken and fibrotic with very thin or no endometrium in 13 cases in the vaporization group and was of normal volume with hypotrophic mucosa in one. In the resection group, the uterine cavity was tunnel-shaped with abolished cornual recesses and very thin or no endometrium in 12 cases and was of normal volume with hypotrophic mucosa in three. Stenosis of the internal os prevented hysteroscope insertion in one woman in each group. Histologic examination of tissue samples removed with curette or suction found proliferative or secretory mucosa in three and five subjects in the vaporization group and four and three subjects in the resection group, respectively. The endometrium was absent or insufficient in seven (47%) cases after vaporization and nine (56%) after resection.


   Discussion
Top
Abstract
 Materials and Methods
 Results
 Discussion
References
 
The objective of endometrial ablation is to destroy or remove the mucosal lining and a layer of about 3 mm of the internal myometrium.21,22 The inactive endometrium induced by a 2-month GnRH treatment is about 1-mm thick.12,17,18 The mean depths of furrows with a vaporizing electrode or standard cutting loop were similar, slightly more than 3 mm.12 The mean depth of thermal necrosis induced under the ablated area by the electrode is 1.8 mm compared with only 0.4 mm induced by the loop,12 which should result in differences in intraoperative fluid absorption because the myometrial veins are coagulated and sealed to a greater extent by the electrode than the loop. The electrode limited distension medium deficit appreciably compared with the loop, allowing the procedure to be done within a very comfortable range of medium deficit. Only one woman absorbed more than 500 mL in the endometrial vaporization group compared with 14 in the resection group, which should increase the safety margins of endometrial ablation, especially when done by less experienced hysteroscopists, without the compulsion to complete the intervention rapidly because the fluid balance is approaching a dangerous zone. In the present study, the mean difference of 258 mL did not have a clinical effect.

Fluid deficit was chosen as the primary outcome of interest because excessive absorption of irrigating solutions remains the most frequent, enigmatic, and severe intraoperative complication of endometrial ablation.7,8,23 Some fluid was inevitably lost on the floor and in the surgical drapes, influencing the precision of estimates of fluid deficit calculated with our method. Great attention was paid to limit that loss, which is unavoidable and common to all systems of measuring intrauterine infusion volumes.

Endometrial vaporization was significantly easier than resection. Admittedly, this finding is weakened by the open-label design with highly subjective and potentially biased global assessments of operating conditions. The surgeon was obviously not masked to electrode used, which could have influenced data collection. Dichotomizing data in two hard outcomes (none and minimal difficulty versus moderate and severe difficulty) should have limited the effect of subjectivity; however, the main outcome measure of the study was fluid deficit, which can be considered more objective. The slight, statistically significant, between-group difference in operating time is probably of no practical benefit. The mean operating time in the resection group was only 10.7 minutes, despite moderate to severe difficulty in 30% of procedures, which might be explained by experience gained in dealing quickly with difficult cases, to limit fluid absorption, and by avoidance, whenever possible, of repeated interruptions to remove endomyometrial fragments.

We hypothesized that the greater depth of coagulation beneath furrows obtained with the vaporizer should have resulted in a greater reduction in monthly blood loss. Unexpectedly, the effect on menstrual flows was almost identical in the two groups 1 year after surgery. A possible explanation is that residual endometrium left at the internal cervical os might colonize the ablated uterine cavity and cover it partially or totally, independent of the depth of destruction achieved by the procedure. That is substantiated by similar observations at second-look hysteroscopies and finding a limited amount of endometrium in most histologic specimens. Satisfaction was very high in both groups, and although long-term results might vary, there was no evidence of a potentially less favorable outcome after endometrial resection. Subjects’ awareness of the technique might have favored the new operation, but adoption of a reliable semiquantitative method to assess postsurgical menstrual blood loss and objective measurements such as serum hemoglobin, hematocrit, and iron values should have limited that bias. In our experience, complete absence of menstrual flow after endometrial ablation is not always the most desirable outcome. Women might dislike postoperative amenorrhea because they lack proof of not being pregnant or they feel it is not physiologic, which might explain why only 9% of women allocated to resection were very satisfied at 1 year, whereas 48% of them were amenorrheic.

The electrical density sufficient for physical elimination of tissue and underlying coagulation required use of high power.12–15 In theory, holding the activated electrode steady in the cornual recesses for a long time might be dangerous and lead to transmyometrial transmission of energy. Because of that risk, common to the rollerball electrode,9 cutting loop,21,24 and neodymium: yttrium-aluminum-garnet (Nd-YAG) laser,25 keeping vaporizer moving is recommended when activating the electrogenerator. Applying pure undampened current should limit thermal necrosis diffusion compared with the coagulation modality.26 An in vivo histochemical study found no sign of tissue damage approaching the uterine serosa.12 In our department, in which more than 150 endometrial vaporizations have been done since 1995, no complications have developed due to application of electricity.

Vaporization, like all the ablative techniques except resection, does not allow endometrial sampling; therefore, thorough preoperative histologic mucosal evaluation is mandatory.

We believe the vaporizing electrode is advantageous for endometrial ablation because it is as rapid and effective as the loop and as simple and safe as the rollerball. Similar results are probably obtainable with the Nd-YAG laser,27 but at greatly increased costs. It would be interesting to compare the safety, ease, efficacy, tolerability, and costs of hysteroscopic vaporization with those of thermal balloon endometrial ablation, a technique that is gradually gaining popularity for treating menorrhagia not associated with organic lesions.28–30


   Footnotes
 
The vaporising electrodes used in this trial were kindly donated by Circon Acmi, Stamford, Connecticut.

PII S0029-7844(99)00327-0

Received October 22, 1998. Received in revised form February 26, 1999. Accepted March 11, 1999.


   References
Top
Abstract
 Materials and Methods
 Results
 Discussion
 References
 
1. O’Connor H, Magos A. Endometrial resection for the treatment of menorrhagia. N Engl J Med 1996;335:151–6.[Abstract/Free Full Text]

2. O’Connor H, Broadbent JA, Magos AL, McPherson K. Medical Research Council randomised trial of endometrial resection versus hysterectomy in management of menorrhagia. Lancet 1997;349: 897–901.[Medline]

3. Crosignani PG, Vercellini P, Apolone G, De Giorgi O, Cortesi I, Meschia M. Endometrial resection versus vaginal hysterectomy for menorrhagia. Am J Obstet Gynecol 1997;177:95–101.[Medline]

4. Crosignani PG, Vercellini P, Mosconi P, Oldani S, Cortesi I, De Giorgi O. A levonorgestrel-releasing intrauterine device versus hysteroscopic endometrial resection in the treatment of dysfunctional bleeding. Obstet Gynecol 1997;90:257–63.[Abstract]

5. Scottish Hysteroscopy Audit Group. A Scottish audit of hysteroscopic surgery for menorrhagia: Complications and follow-up. Br J Obstet Gynaecol 1995;102:249–54.[Medline]

6. Overton C, Hargreaves J, Maresh M. A national survey of the complications of endometrial destruction for menstrual disorders: The MISTELTOE study. Br J Obstet Gynaecol 1997;104:1351–9.[Medline]

7. Istre O, Skajaa K, Schoensbye A, Forman A. Changes in serum electrolytes after transcervical resection of endometrium and submucous fibroids with use of glycine 1.5% for uterine irrigation. Obstet Gynecol 1992;80:218–22.[Abstract/Free Full Text]

8. Witz CA, Silverberg KM, Burns WN, Schenken RS, Olive DL. Complications associated with the absorption of hysteroscopic fluid media. Fertil Steril 1993;60:745–56.[Medline]

9. Valle RF. Rollerball endometrial ablation. Baillière’s Clin Obstet Gynaecol 1995;9:299–316.

10. Chullapram T, Song LY, Fraser IS. Medium-term follow-up of women with menorrhagia treated by rollerball endometrial ablation. Obstet Gynecol 1996;88:71–6.[Abstract]

11. Unger JB, Meeks GR. Hysterectomy after endometrial ablation. Am J Obstet Gynecol 1996;175:1432–7.[Medline]

12. Vercellini P, Oldani S, Milesi M, Rossi M, Carinelli S, Crosignani PG. Endometrial ablation with a vaporizing electrode. I. Evaluation of in-vivo effects. Acta Obstet Gynecol Scand 1998;77:683–7.

13. Vercellini P, Oldani S, De Giorgi O, Milesi M, Merlo D, Crosignani PG. Endometrial ablation with a vaporizing electrode. II. Clinical outcome of a pilot study. Acta Obstet Gynecol Scand 1998;77:688–93.[Medline]

14. Brooks PG. Resectoscopic myoma vaporizer. J Reprod Med 1995; 40:791–5.[Medline]

15. Kaplan SA, Te AE. Transurethral electrovaporization of the prostate: A novel method for treating men with benign prostatic hyperplasia. Urology 1995;45:566–72.[Medline]

16. Higham JM, O’Brien PMS, Shaw RW. Assessment of menstrual blood loss using a pictorial chart. Br J Obstet Gynaecol 1990;97: 734–9.[Medline]

17. Brooks PG, Serden SP, Davos I. Hormonal inhibition of the endometrium for resectoscopic endometrial ablation. Am J Obstet Gynecol 1991;164:1601–8.[Medline]

18. Vercellini P, Perino A, Consonni R, Trespidi L, Parazzini F, Crosignani PG. Treatment with a gonadotropin-releasing hormone agonist before endometrial resection: A multicentre randomised controlled trial. Br J Obstet Gynaecol 1996;103:562–8.[Medline]

19. Ankum WM, Vonk J. The spring balance: A simple monitoring system for fluid overload during hysteroscopic surgery. Lancet 1994;343:836–7.[Medline]

20. Chandler CJ, Ford PM. Monitoring of fluid overload during hysteroscopic surgery. Lancet 1994;343:1368.[Medline]

21. Sutton CJG, Macdonald R, Magos AL, Broadbent JAM. Endometrial resection. In: Lewis BG, Magos AL, eds. Endometrial ablation. Edinburgh, UK: Churchill Livingstone, 1993:91–131.

22. Onbargi LC, Hayden R, Valle RF, Del Priore G. Effect of power and electrical current density variations in an in vitro endometrial ablation model. Obstet Gynecol 1993;82:912–8.[Abstract/Free Full Text]

23. Baskett TF, Farrell SA, Zilbert AW. Uterine fluid irrigation and absorption in hysteroscopic endometrial ablation. Obstet Gynecol 1998;92:976–8.[Abstract]

24. Duffy S, Reid PC, Smith JHF, Sharp F. In vitro studies of uterine electrosurgery. Obstet Gynecol 1991;78:213–20.[Free Full Text]

25. Garry R. Good practice with endometrial ablation. Obstet Gynecol 1995;86:144–51.[Abstract]

26. Soderstrom R. Principles of electrosurgery as applied to gynecology. In: Rock JA, Thompson JD, eds. Te Linde’s operative gynecology. 8th ed. Philadelphia: Lippincott-Raven, 1996:321–36.

27. Garry R, Shelley-Jones D, Mooney P, Phillips G. Six hundred endometrial laser ablations. Obstet Gynecol 1995;85:24–9.[Abstract]

28. Singer AA, Almanza R, Gutierrez A, Haber G, Bolduc L, Neuwirth RS. Preliminary clinical experience with a thermal balloon endometrial ablation method to treat menorrhagia. Obstet Gynecol 1994;83:732–4.[Medline]

29. Neuwirth RS, Duran AA, Singer A, MacDonald R, Bolduc L. The endometrial ablator: A new instrument. Obstet Gynecol 1994;83: 792–6.[Medline]

30. Amso NN, Stabinsky SA, McFaul P, Blanc B, Pendley L, Neuwirth R. Uterine thermal balloon therapy for the treatment of menorrhagia: The first 300 patients from a multi-centre study. Br J Obstet Gynaecol 1998;105:517–23.[Medline]





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