Bipolar vaporization of the prostate: is it ready for the primetime? (2024)

Keywords: transurethral prostate resection, bipolar vaporization, benign prostatic hyperplasia

Standard monopolar resection of the prostate

In 1929, McLean was one of the first authors who studied and presented the principles of electrosurgery [McLean, 1929]. After the introduction of the electrosurgery generator device, developed by Bovie and Cushing, one of its initial applications was the resectoscope, in the 1930s [Kaplan and Te, 1995]. The resection loop was mounted on an adapted cystoscope and the high frequency electrosurgery generator was able to deliver both cutting and coagulation current.

Despite all of the subsequent technical improvements (high-performance electrosurgery generators, better resectoscope and loop materials, better irrigation, etc.), the technical principle behind TURP remains the same as 80 years ago, with all of its derived disadvantages, including the use of hypotonic irrigation solutions, which may cause the TURP syndrome [Thiel and Petrou, 2009].

Initial transurethral vaporization (TUVP) technique and results

Initial monopolar electrovaporization of the prostate, introduced 20 years ago, used an electric current with a higher power (compared with standard cutting) and a specially designed roller electrode, to vaporize the prostatic tissue. The procedure was performed under water and glycine irrigation [Kaplan and Te, 1995]. The method was gradually abandoned, as a consequence of a high amount of remaining tissue coagulation (up to 1 cm), which was associated with significant postoperative side effects (irritative LUTS, even incontinence) [Reich et al. 2010].

Technical improvements: bipolar saline resection

Initially, monopolar TURP has used an active resection electrode loop and a return electrode at skin level, to close the circuit [Issa, 2008]. The energy had to travel through the body, raising the risk of nervous stimulation and eventual pacemaker failure; moreover, significant bleeding may occur during cutting with a monopolar loop, raising the need for frequent coagulation, a process that increases the overall procedure time [Thiel and Petrou, 2009].

One significant technical advance of TURP was represented by the introduction of bipolar technology, allowing the resection in saline medium, thus avoiding the risks of dilutional hyponatremia and subsequent TUR syndrome. Bipolar devices have both the active and return poles incorporated into the electrode, or in the electrode and the resectoscope [Smith et al. 2005]. The method has a much shorter tissue penetration, of about 50–100 µm, generating less collateral thermal damage and less tissue charring [Thiel and Petrou, 2009].

Contemporary bipolar prostate vaporization

The most recent technical solution has managed to combine prostate vaporization with bipolar resection, so bipolar vaporization of the prostate was introduced. The first studies which have utilized the new technique have shown much smaller zones of tissue coagulation than the conventional monopolar vaporization [Reich et al. 2010]. Plasma vaporization is realized without direct tissue contact, with minimal heat generation. The bipolar electrode generates a thin layer of highly ionized particles, allowing it to glide over the tissue. After the generation of an initial electrical pulse, a constant plasma field is created, allowing it to vaporize a limited layer of prostate cells, without affecting the underlying tissue [Ho and Cheng, 2008]. As a consequence of this technique, which realizes concomitant vaporization and coagulation, the bleeding is reduced significantly. Moreover, any potential bleeding can be stopped immediately by applying the electrode at the level of the open vessel in the coagulation mode [Botto et al. 2001].

One interesting therapy option could be the combination between bipolar vaporization and bipolar resection of the prostate, allowing the urologist to reduce the time of the procedure, while giving all of the advantages of improved hemostasis. Moreover, this could be realized by replacing only the bipolar vaporization electrode with the bipolar resection loop, while using the same resectoscope, high-frequency generator, and irrigation solution [Reich et al. 2010; Tefekli et al. 2005].

Electrode types

At the time of writing, there are three companies which provide complete bipolar vaporization systems, with their own resectoscopes and high-frequency energy generators.

The most widely used system for bipolar vaporization is the one produced by Olympus, the ‘TURis’ plasma vaporization electrode, which was launched in 2008 (after the incorporation of Gyrus Acmi, the first company that introduced bipolar vaporization 10 years ago, into Olympus). This electrode has a semispherical shape, is ‘mushroom’ like, and is integrated into a new bipolar resectoscope design, with the electrical current circuit closing at the resectoscope sheath level.

Another bipolar vaporization electrode is that produced by Karl Storz: it also has a semispherical shape, is ball like, but the circuit is closed at the level of the electrode, with an additional loop located immediately over the working loop.

Finally, the new bipolar vaporization electrode proposed by Richard Wolf, has a ‘step-shaped’ design, created to reduce the energy density in the resection area.

Meta-analysis of the current results

In the most comprehensive recent meta-analysis of functional outcomes and complications following transurethral procedures for LUTS due to BPH, published in 2010, only four studies on bipolar transurethral vaporization were randomized, controlled trials (RCTs) [Ahyai et al. 2010]. We analyze their results in the following sections.

Functional outcomes

The total number of patients who underwent bipolar transurethral vaporization (TUVP) during the four trials was 187. The meta-analysis of functional results has shown that the variations of International Prostate Symptom Score (IPSS) and of the IPSS Quality of Life (QoL) index were similar after bipolar TUVP and TURP, with no statistically significant differences. The same similarities were observed regarding postoperative peak urinary flow rate (Qmax) and postvoid residual volume (PVRV) [Ahyai et al. 2010; Dunsmuir et al. 2003]. We can conclude, from these results, that the efficacy of TUVP is very close to that of TURP; finally, we are comparing two procedures which depend on removing obstructive tissue, leaving in place a similar prostatic cavity [Kaplan and Te, 1995].

Catheter removal was done earlier after bipolar TUVP (1.3 days) than after TURP (2.8 days), while mean operation time for bipolar TUVP was 36 minutes, significantly shorter than the mean duration of TURP [Ahyai et al. 2010].

Individual trials

The study published by Tefekli and colleagues in 2005 has proposed a ‘hybrid’ technique, which combined bipolar prostate vaporization with classical prostate resection [Tefekli et al. 2005]. Initially, the lateral and median lobes were removed by vaporization, while the apical tissue in the vicinity of veru montanum was removed using the resection loop, also allowing tissue sampling for the pathology report. The outcomes of the 49 patients who were operated by using this approach were very similar with those of the 47 patients operated by TURP, as the control group. Severe irritative symptoms were the most frequent adverse effects after bipolar vaporization, occurring in 12.2% of the cases. During late postoperative follow up there were significantly more urethral strictures. This observation, on an initial model of bipolar vaporization, was not confirmed by further studies, which have used improved equipment. Mean operative time, irrigation volume and catheterization and hospitalization time were significantly reduced by using bipolar vaporization. The authors of the study have concluded that the new technique can be performed ‘in an almost bloodless manner, which decreases the time for controlling bleeding vessels and improves intraoperative vision’ [Tefekli et al. 2005].

In another randomized, controlled study, published by Hon and colleagues in 2006, the authors demonstrated that bipolar TUVP is equally effective as TURP in improving symptoms and uroflowmetry parameters, mentioning that bipolar TUVP is slightly better for resolving significant obstruction. One important issue raised by the authors was the fact that, due to complete vaporization of the prostatic tissue, no histological specimen is available for pathological examination. As a consequence, some cases of significant prostate cancer could be missed, so careful follow up of the operated patients is necessary [Hon et al. 2006].

The randomized, controlled study performed by Kaya and colleagues in 2007 has compared the long-term results of bipolar TUVP with those of TURP. Although it was conducted on a limited number of patients (25 with bipolar TUVP and 15 with TURP), it is the only study with a postoperative follow up of 3 years. Its results were interesting, showing a slight superiority of TURP: the improvement of IPSS was significantly better in patients after TURP than after bipolar TUVP at 2 years, but this improvement become similar at 3 years from the interventions. A significant difference of Qmax values was also noted in favor of TURP, both at 2 and 3 years postoperatively. The complication rates were similar after the two procedures, but the overall incidence of secondary surgery was 12% for bipolar TUVP and only 6.6% for TURP. The authors concluded that, although the patient sample was reduced, the long-term clinical outcome of bipolar TUVP was slightly inferior to that of TURP [Kaya et al. 2007; Karaman et al. 2005].

Finally, during a prospective, bicentre study, 30 patients underwent bipolar TUVP with the new ‘mushroom’-like electrode (produced by Olympus) [Reich et al. 2010]. Postoperative evaluation was done at hospital discharge, after 1 month, 3 months, and 6 months, respectively. The results were impressive: the clinical improvement was significant for all evaluated parameters (IPSS, Qmax, and PVRV), and has been maintained during the whole 6-month interval. The mean catheterization time was 41 hours and 13% of patients had to be recatheterized temporarily in less than 24 hours after initial catheter removal. During the 6-month follow-up period, one patient had to be re-operated by TURP due to persistent obstructive voiding. Transient mild to moderate dysuria was observed in 13% of patients, which was resolved with anti-inflammatory drugs. The authors underline that prospective, randomized trials of bipolar TUVP against TURP and laser vaporization, with longer follow up, are absolutely necessary to confirm the safety of the method [Reich et al. 2010].

Holmium laser enucleation of the prostate versus bipolar vaporization of the prostate

The safety profile of holmium laser enucleation of the prostate (HoLEP), very similar to that of TURP, together with its excellent long-term postoperative results, and with the fact that the procedure does not depend on prostate size, makes the procedure a very strong competitor for the role of the new gold standard in transurethral surgery for BPH [Ahyai et al. 2010]. Unfortunately, at this moment we do not have available any data comparing directly the results of HoLEP with those of bipolar vaporization of the prostate. Perhaps future randomized, prospective trials will address this comparison between two emerging technologies.

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