The Use of VaperTrode® Vaporization Electrode in Operative Hysteroscopy

For the gynecologist, the introduction of the resectoscope revolutionized the management of submucous myomata that cause uncontrollable uterine bleeding, infertility and pregnancy wastage, and the con-servative control of persistent and excessive uterine bleeding unrelated to uterine filling defects. Electrodes such as wire loops, rollerballs, and roller cylinders initially were used for the resection of myomas and polyps and endometrial ablation procedures. Numerous studies have confirmed the success and safety of procedures with resectoscopes to correct these problems.

However, one of the more significant difficulties encountered during resection of myomata and/or the endometrium (during ablation procedures) is the accumulation of tissue "chips," requiring repeated withdrawal of the resectoscope, removal of resected tissue, and reinsertion of the resectoscope. This may result in prolongation of the procedure and an increased risk of introducing infection.

In 1995, stimulated by the enormous urologic success of the vaporization technique for treatment of benign prostatic hypertrophy, I began a trial with a new vaporization instrument, the Grooved VaporTrode Vaporization Electrode, to destroy myomata and for endometrial ablation.

VaporTrode Mechanism of Action

The first vaporizing electrode developed by CIRCON ACMI was the VaporTrode Grooved Bar (Figure 1). The electrode has both thin ridges for high current density and effective vaporization, and a contact area between the grooves which separates the ridges. This configuration utilizes the long-known property of electricity called "edge density," which is the concentration of electrons and therefore energy at the edges of a non-spherical electrode. Using higher wattage and the Grooved VaporTrode, urologists and gynecologists are able to more efficiently vaporize tissue in contact with the electrode. For gynecological use, the result is the actual destruction and/or morcellation of myomas and endometrial surfaces. Because of the tissue heat produced by the energy density or concentration of energy, blood vessels are coapted and sealed, markedly reducing the risk of bleeding and intravasation of distention media. Additionally, in contrast to resection, vaporization allows the morcellation of myomas into several fragments easily extracted from the uterine cavity instead of numerous smaller chips that require repeated extractions to clear the field of view.

Room Setup & Equipment

The basic operating room setup is the same as for any other resectoscopic procedure. We use a CIRCON ACMI rotating continuous flow resectoscope with a 12° telescope. Instead of a wire loop, a Grooved VaporTrode is used. Three VaporTrode configurations are available - fluted, spiked, and grooved - designed to accommodate diverse surgical techniques and types of electrosurgical generators. Depending on the capabilities of the generator, the wattage is set from 160W to 200W in a pure CUT waveform. (Some urologists use up to 300W for electrovaporization of the prostate.)

Management of Myomas and Giant Polyps

I generally start in the center of the tumor and initially "bivalve" it by vaporizing a wide swath down the middle, to about the level of the endomyometrial junction (Figure 2). If the resulting pieces are small enough to extract, the resectoscope is removed and an ovum forceps or a myoma grasper is inserted. The myoma is firmly grasped, avulsing the remaining portion with a gentle, twisting motion. Large pieces are further morcellated and then extracted. The resectoscope is reinserted and, using either the VaporTrode or a wire loop electrode (remember to lower the wattage to about 110W pure cut current for the wire loop), the remaining intracavitary portions of the tumors and/or their stalks are shaved or vaporized. Bleeding points are coagulated with either electrode, using about 60W to 70W of a damped or coagulating waveform.

Because of the small, but not insignificant, risk of unknowingly vaporizing malignant tissue, a portion of the polyp or myoma must always be removed and sent for pathologic examination. In our series of over 700 myoma resections, we have had two patients with unsuspected leiomyosarcoma.

Another critical point to remember is that once a specimen is severed from its uterine attachment, the energy pathway to the return electrode (or "ground plate") is lost, making further electrical morcellation or vaporization of the detached tissue almost impossible.

For polyps small enough to be extracted through a dilated cervical canal, it is only necessary to vaporize the base or stalk and then extract the polyp with an ovum forceps or a myoma grasper. Larger polyps and submucous myomas are treated similarly.

Endometrial Ablation

To avoid the risk of destroying unsuspected atypical endometrium, even when preoperative sampling was negative, I usually biopsy the endometrium for pathologic exam at the beginning of every VaporTrode endometrial ablation. First, using a wire loop electrode and about 100W of pure cut current, several strips of endomyometrium are shaved from the posterior surface and then the anterior surface. These strips are removed for pathologic examination, leaving furrows of about 4 mm deep to be used as guides to determine the depth of vaporization. The wire loop is replaced with a VaporTrode, and using 160W to 200W of pure cut current, the endomyometrium is sequentially vaporized, leaving the cornual areas for last, until all viable appearing tissue is vaporized and dessicated (Figure 3). For the thinner cornual areas, the current is reduced to 80W or 90W and the surface is desiccated only, rather than vaporized.

It should be obvious that the procedure is made easier and more effective if the endometrium is thinned. Our preference is the use of a GNRH analogue, such as leuprolide acetate-depot, one month prior to the procedure, although scheduling during the proliferative phase of a cycle (i.e., days 4 to 7), or using a thorough curettage prior to the procedure has been reported almost as effective. Preoperative preparation with danazol, usp is also very effective to thin the endometrium, but the use of progestins has been disappointing.

Results

Vaporization of Myomas

From December 1994 through December 1996, I used the VaporTrode for myomectomy in 42 patients with complaints of menorrhagia due to submucous myomas. To date there have been no failures, no complications, and no need for further treatment. The estimated blood loss was under 100 ml in 41 cases and 250 ml in the other. In no case was there a fluid discrepancy (intravasation) of greater than 300 ml.

Endometrial Vaporization

From April 1995 through December 1996, the VaporTrode was used to perform endometrial vaporization ablation in place of standard ablation in 19 patients. In all 19 patients the estimated blood loss was less than 50 ml and fluid discrepancy was less than 100 ml. Fifteen of the 19 patients have amenorrhea and the other 4 have hypomenorrhea.

Summary

It is too soon to say with confidence if this technique has better long-term results than standard ablation methods, but preliminary results are very promising. However, once trained in this method (sidebar), a skilled hystero-scopist will soon realize the evident advantages in terms of therapeutic efficacy, reduced operative time, and increased safety (less bleeding and less intravasation).

Suggested Reading

 
Recommendations for Maximizing the Efficiency of Electrovaporization

Dr. Brooks is a clinical professor, department of obstetrics and gynecology, UCLA School of Medicine, and attending physician, department of obstetrics and gynecology, Cedars-Sinai Medical Center, Los Angeles, CA.