Waveforms for Endometrial Ablation Compared : When using the rollerball, cutting and coagulation are equally effective, a first-ever study concludes.


LAS VEGAS — Cutting and coagulation waveforms are equally effective for hysteroscopic endometrial ablation using the rollerball, results from the first clinical study of its kind demonstrated.

An in vitro study from the early 1990s showed that the depth of thermal injury to 3 mm of myometrium (the depth of destruction believed to completely destroy the basal layer) was found to be more consistent with use of the low-voltage cut waveform compared with the high-voltage modulated coag waveform (Obstet. Gynecol. 1993;82:912–8). However, no published clinical trial has compared the two radiofrequency waveforms after rollerball endometrial ablation, Dr. Paul T. Chang said at the annual meeting of the AAGL.

The low-voltage cut waveform, which heats the tissue more slowly, “is more likely to result in deep and homogenous tissue penetration, while the high-voltage modulated coag waveform is more likely to result in superficial tissue desiccation and subsequent increase in tissue impedance,” said Dr. Chang, a specialist in minimally invasive gynecology and infertility at the Toronto Centre for Advanced Reproductive Technology.

In a trial intended to serve as a pilot study for a larger randomized trial, Dr. Chang and his mentor, Dr. George A. Vilos of the University of Western Ontario, London, allocated 47 premenopausal women to hysteroscopic electrocoagulation of the endometrium using a 5-mm diameter rollerball with cut or coag waveforms at 100 watts of power. Eligibility criteria included symptomatic menorrhagia, no desire for future pregnancy, no intramural or submucosal myomas 3 cm or larger, no active pelvic inflammatory disease, and no atypical endometrial hyperplasia or cancer. The average age of the patients was 41 years and the average body mass index was 28 kg/m

Of the 55 women 22 were in the cut waveform group and 23 were in the coag waveform group. One physician experienced in hysteroscopic surgery and two surgical fellows performed all procedures at St. Joseph's Health Care in London, Ont., between November 2004 and March 2005.

Primary outcomes included rates of menstrual reduction, need for reintervention, patient satisfaction as measured by questionnaires, and complications. Two-year follow-up was completed by either questionnaires or telephone contact.

Dr. Chang and his associates hypothesized that patients in the cut waveform would have superior clinical outcomes compared with those in the coag waveform group. However, at 2 years of follow-up, the rate of hypomenorrhea was 52% in the coag group and 32% in the cut group, a difference that was not statistically significant.

There were no statistically significant differences between the coag and cut waveform groups in terms of amenorrhea rates (28% vs. 36%, respectively); reintervention rates (32% vs. 36%), and the percentage of women who reported being either satisfied or very satisfied with the results (68% vs. 64%). No complications occurred in either group.

Dr. Chang pointed out that the trend toward higher amenorrhea rates in the cut waveform group “supports in vitro findings. One significant observation was that the rollerball electrode was rapidly covered with coagulated tissue when using the cut waveform,” he added. “This required the scope to be withdrawn and the rollerball to be cleaned several times during the procedure.” Based on this analysis, he and his associates concluded that both waveform types are safe and equally effective for hysteroscopic endometrial ablation using the rollerball.

Dr. Chang stated that he had no conflicts of interest to disclose.

The low-voltage cut waveform is more likely to result in deep and homogenous tissue penetration. DR. CHANG

Hysteroscopic view of uterine cavity: Rollerball electrode is at upper left.

Brown tissue is area of thermal damage from ablation with a coag waveform. Photos courtesy Dr. Paul T. Chang

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