What's known on the subject? and What does the study add?
According to the EAU Guidelines 2012, large size benign prostatic hyperplasia (BPH) cases (>80 mL) continue to have open prostatectomy as the first line treatment alternative, despite the substantial peri-operative morbidity and extended catheterization and convalescence periods related to this undoubtedly invasive approach. During the past two decades, holmium laser enucleation of the prostate was constantly described as a successful choice for this category of patients. According to rather numerous studies, the technique displayed superior results in terms of surgical safety and postoperative recovery compared with the open procedure. On the other hand, the concept of electrosurgical enucleation of the prostate, using either a monopolar or bipolar cutting current, materialized into several technical applications that eventually failed to gain general acknowledgement as reliable alternatives to the BPH transurethral approach.
While keeping in mind the already proved advantage of enucleating substantial quantities of BPH tissue, bipolar plasma enucleation of the prostate was introduced as a novel endoscopic approach in cases of large prostates. The present trial represents the first prospective, medium-term, randomized comparison to be published of this innovative technique with standard open prostatectomy. Basically, the premises for a viable alternative relied on the practical advantages provided by the ‘button’ electrode, mainly the large surface creating the conditions for a fast enucleation process, continuous vaporization and concomitant haemostasis. Eventually, it was concluded that the plasma enucleation procedure distinguished itself as a successful treatment option in large BPH patients, characterized by good surgical efficiency, significantly reduced complications, faster postoperative recovery, similar prostatic tissue ablation capabilities and satisfactory follow-up results compared with the open technique. Most importantly, plasma-button enucleation patients benefited from a similar 12 months' outcome from the perspectives of symptom scores and voiding parameters when drawing a parallel with open surgery results, thus underlining the reliable viability of this type of endoscopic approach.
To evaluate the viability of bipolar plasma enucleation of the prostate (BPEP) by comparison with open transvesical prostatectomy (OP) in cases of large prostates with regard to surgical efficacy and peri-operative morbidity.
To compare the medium-term follow-up parameters specific for the two methods.
Patients and Methods
A total of 140 benign prostatic hyperplasia (BPH) patients with prostate volume >80 mL, maximum flow rate (Qmax) <10 mL/s and International Prostate Symptom Score (IPSS) >19 were randomized in the two study arms.
All cases were assessed preoperatively and at 1, 3, 6 and 12 months after surgery by IPSS, Qmax, quality of life score (QoL) and post-voiding residual urinary volume (PVR).
The prostate volume and prostate specific antigen (PSA) level were measured at 6 and 12 months.
The BPEP and OP techniques emphasized similar mean operating durations (91.4 vs 87.5 min) and resected tissue weights (108.3 vs 115.4 g).
The postoperative haematuria rate (2.9% vs 12.9%) as well as the mean haemoglobin drop (1.7 vs 3.1 g/dL), catheterization period (1.5 vs 5.8 days) and hospital stay (2.1 vs 6.9 days) were significantly improved for BPEP.
Recatheterization for acute urinary retention was more frequent in the OP group (8.6% vs 1.4%), while the rates of early irritative symptoms were similar for BPEP and OP (11.4% vs 7.1%).
During the follow-up period, no statistically significant difference was determined in terms of IPSS, Qmax, QoL, PVR, PSA level and postoperative prostate volume between the two series.
BPEP represents a promising endoscopic approach in large BPH cases, characterized by good surgical efficiency and similar BPH tissue removal capabilities compared with standard transvesical prostatectomy.
BPEP patients benefited from significantly reduced complications, shorter convalescence and satisfactory follow-up symptom scores and voiding parameters.
From a certain perspective of BPH pathology, it was observed that, while a variety of therapeutic solutions and technical innovations focused on bringing improvements to BOO endoscopic treatment, large size BPH cases (>80 mL) continue to have open prostatectomy (OP) as the first line alternative according to the European Association of Urology Guidelines . The downside of this undoubtedly invasive approach was described to consist of substantial peri-operative morbidity as well as extended catheterization and convalescence periods .
Some therapeutic modalities followed the concept of electrosurgical enucleation of the prostate and acquired a relative degree of success. For example, the plasmakinetic enucleation of the prostate was at a certain moment described as highly effective in relieving BOO, thus comparing favourably with standard TURP . On the other hand, this apparently safe and technically feasible procedure failed to match the peri-operative results of holmium laser enucleation of the prostate (HoLEP) . In any case, these initial series only consisted of medium BPH cases, consequently leaving the issue of the large adenoma endoscopic approach still under debate [3-5].
From another point of view, bipolar plasma vaporization of the prostate using the ‘button’ electrode was described as a safe and efficient treatment modality for average size (30–80 mL) BPH patients. According to some short-term  as well as medium- term  prospective randomized trials, the plasma vaporization technique produced significantly improved symptom scores and voiding parameters compared with either standard monopolar [6, 7] or bipolar  resection.
As a distinct drawback of this type of procedure, it was found that simple bipolar vaporization was only slightly effective for dealing with high volume BPH formations and that a new use of the plasma-button concept would most probably be required. Therefore, while keeping in mind the already proved advantage of enucleating large quantities of BPH tissue, bipolar plasma enucleation of the prostate (BPEP) was introduced as a novel endoscopic approach . Naturally, a clinical comparison with standard OP in a randomized setting became necessary before eventually considering this new technique as part of the acknowledged BPH therapeutic armamentarium.
Patients and Methods
Based on these premises, a single centre, prospective, randomized, medium-term trial was performed, aiming to compare the plasma enucleation of the prostate to OP in a series of large BPH patients with indication for surgery. As far as the primary endpoints of the study were concerned, the viability of the two types of approach was comparatively assessed from the perspectives of peri-operative and safety characteristics as well as follow-up symptom scores and urodynamic results determined during a 1-year evaluation period.
The study was approved by the local ethics and research committee. A total of 140 patients with a mean age of 70.4 years (range 54–87) and diagnosed with large volume prostates and severe lower urinary tract symptoms were included in this analysis. The patients were enrolled under approved written informed consent (properly explaining the aims, methods, anticipated benefits and potential hazards relevant for the decision to participate in the trial) and randomized by means of sealed envelopes.
A standard investigation protocol which included general clinical evaluation with digital rectal examination, blood tests, PSA, urinalysis, urine culture, IPSS, quality of life score (QoL), uroflowmetry (evaluating the maximum flow rate Qmax) and abdominal and transrectal ultrasound measuring the prostate volume and the post-voiding residual urinary volume (PVR) was used in all cases.
A total of 70 patients were distributed in each study arm. The inclusion criteria consisted of Qmax <10 mL/s, IPSS >19 and prostate volume >80 mL. Patients with severe associated comorbidities, previous prostate surgery or history of prostate cancer were excluded from the trial.
Standard OP was performed using the transvesical approach. The equipment for the plasma enucleation procedure was represented by the Olympus SurgMaster UES-40 bipolar generator, the OES-Pro bipolar resectoscope, saline continuous flow irrigation, ‘button’ type vapo-resection electrodes (Olympus Europe, Hamburg, Germany) and the Wolf Piranha morcellator.
From the point of view of surgical strategy, the technique was based on the by now classical steps of laser enucleation. During the first endoscopic stage, after an initial cysto-urethroscopic assessment of the prostatic bulk, the median lobe enucleation was achieved by 5 and 7 o'clock incisions starting from the bladder neck and continuing up to the level of the verumontanum (Fig. 1). The next step started with a deep incision at 12 o'clock, which resulted in complete separation of the two lateral lobes and was followed by their enucleation in a descendant direction, beginning from the 1 and 11 o'clock positions (Fig. 2). This process continued from the 5 and respectively 7 o'clock incisions in an ascendant sense until the respective lobes were gradually detached from the prostatic capsule and pushed back into the bladder (Fig. 3).
The remaining adenoma tissue was then ablated by simple plasma vaporization and the procedure was concluded with the careful coagulation of any haemorrhagic sources (Fig. 4). Last, BPH tissue morcellation was performed under clear endoscopic vision and control and the procedurefinally resulted in a large prostatic fossa without irregularities, debris or obstruction (Fig. 5).
Patients pathologically confirmed with prostate cancer as well as those who failed to complete the 1-year evaluation protocol were excluded from the continuation of the trial. All patients were evaluated preoperatively and at 1, 3, 6 and 12 months after surgery by IPSS, QoL, Qmax and PVR. The postoperative prostate volume (according to TRUS results) and PSA level were measured at 6 and 12 months.
Using SPSS 15.0 software (SPSS Inc., Chicago, IL, USA), the chi-squared test, binomial test, independent samples t test and Mann–Whitney U test were applied in order to determine the statistical significance of differences between various parameters of the study arms. The primary endpoint was to test the null hypothesis that the peri-operative and follow-up features were similar in the BPEP and OP groups. With a sample size of 70 patients in each treatment arm and a confidence level of at least 95%, the trial was determined to have an 80% power to reject the null hypothesis.
The two study arms emphasized similar preoperative parameters in terms of the mean prostate volume, IPSS, QoL, Qmax, PVR and haemoglobin and PSA levels, without any statistically significant differences determined between the respective results (Table 1).
Table 1. Preoperative parameters.
BPEP (N = 70)
OP (N = 70)
NS, not significant.
*Mann–Whitney U test; †independent samples t test.
The plasma enucleation and standard transvesical prostatectomy techniques were successfully completed in all cases. As far as the actual surgical efficiency was concerned, statistically similar data were gathered with regard to the mean operation duration and resected tissue weight for BPEP and OP (Table 2). Additionally, the BPEP approach was characterized by mean enucleation and morcellation times of 74.9 and 16.5 min.
Table 2. Peri-operative features.
BPEP (N = 70)
OP (N = 70)
NS, not significant (P > 0.05); S, significant; SSL, statistical significance limit (0.051 ≤ P ≤ 0.060).
*Mann–Whitney U test; †independent samples t test; ‡chi-squared test.
During the immediate postoperative period, the plasma-button enucleation produced a substantially decreased surgically induced bleeding. Thus the BPEP series displayed significantly reduced mean haemoglobin level drop (1.7 vs 3.1 g/dL) and postoperative haematuria rates (2.9% vs 12.9%) compared with the standard OP study group. Also, the difference in blood transfusion rate (1.4% vs 8.6%) was at the limit of statistical significance in favour of the BPEP approach. Moreover, the plasma enucleation patients benefited from a shorter postoperative recovery, as significantly lower mean catheterization period (1.5 vs 5.8 days) and hospital stay (2.1 vs 6.9 days) were described in comparison with the OP series (Table 2).
With regard to the issue of short-term complications, the BPEP rate of recatheterization for acute urinary retention was decreased compared with transvesical prostatectomy (1.4% vs 8.6%, statistically significant limit). Also, the rates of early irritative symptoms and urinary tract infections were statistically similar in the respective study arms (Table 3).
NS, not significant (P > 0.05); SSL, statistical significance limit (0.051 ≤ P ≤ 0.060).
N = 70
N = 70
Re-catheterization – acute urinary retention
Early irritative symptoms
Urinary tract infections
N = 64
N = 63
Bladder neck sclerosis
After pathological analysis, two prostate cancer cases were diagnosed in each series and excluded from the continuation of the trial. Furthermore, four and five patients respectively of the BPEP and OP groups failed to complete the follow-up protocol and were also discarded from the rest of the study.
During the medium-term evaluation period, a safety profile was outlined for the two therapeutic modalities. From this perspective, similar results were found concerning the rates of bladder neck sclerosis, urethral strictures and urinary incontinence (Table 3).
From the point of view of surgery-related patient comfort and functional outcomes, similar symptom scores and voiding parameters were established as subsequent to BPEP and OP. Therefore, at the 1-, 3-, 6- and 12-month follow-up assessment, no statistically significant difference was determined regarding the mean values of IPSS, QoL, Qmax and PVR specific for the two series of patients (Table 4).
Table 4. Results during the 1-year follow-up.
BPEP (N = 64)
OP (N = 63)
NS, not significant.
*Mann–Whitney U test; †independent samples t test.
Also, at the 6- and 12-month check-ups, similar data were obtained for the mean PSA level and prostate volume (Table 4). Consequently, at the respective time intervals, the calculated prostate volume decrease (83.0% vs 82.1%, P = 0.460; 83.9% vs 82.8%, P = 0.458; binomial test) and PSA level reduction (90.6% vs 90.1%, P = 0.445; 91.1% vs 90.7%, P = 0.455; binomial test) compared with the preoperative measurements were statistically equivalent for the plasma enucleation and transvesical prostatectomy study groups.
So far the concept of electrosurgical enucleation of the prostate has materialized into several technical applications, initially characterized by a certain degree of success, yet eventually failing to gain acknowledgement as reliable alternatives to the BPH transurethral approach .
From this perspective, detachment of residual adenoma tissue secondary to monopolar TURP was performed with a detaching blade . Additionally, standard resection was at some point altered into an enucleation–TURP procedure, during which the conventional endoscopic stages were completed with a bipolar resectoscope-based HoLEP-like technique . Furthermore, the transurethral detachment prostatectomy involving the use of a prostate-detaching blade and resectoscope tip was followed by BPH tissue morcellation [10, 11]. Eventually, the Gyrus bipolar device enabled a plasmakinetic enucleation of the prostate to be accomplished [3, 4].
As far as the actual BPEP intervention was concerned, certain aspects were emphasized as technically relevant. In this regard, during the enucleation process a close contact between the ‘button’ electrode displaying a plasma corona on its surface and the prostatic capsule was carefully maintained. Consequently, a rigorous enucleation plane was persistently created, thus clearly revealing the neat surface and distinctively observable fibres of the capsule (Fig. 6). Ultimately, the operation duration and haemorrhagic risk during surgery were reduced, while the constantly good visibility added to the safety of the morcellation stage .
From a subjective point of view, the BPEP therapeutic modality took advantage of the extended enucleation surface and improved coagulation properties of the ‘button’ electrode. Such features created the basis for a superior enucleation speed and accuracy to be achieved, while at the same time obtaining additional BPH tissue ablation due to the concomitant vaporization phenomenon .
Based on these rather optimistic circumstances, a comparison between BPEP and the standard OP must generally target the most relevant peri-operative and postoperative features. Also, a parallel with HoLEP, the most successful enucleation method defined so far, should also be outlined.
From the perspectives of surgical speed and efficacy, BPEP displayed similar outcomes in terms of operation duration (91.4 min) and resected tissue weight (108 g) to OP, both according to our analysis (86.5 min and 115 g) and according to other published studies (80.8–109.5 min and 84.8–116.8 g [12, 13]) starting from similar preoperative prostate volumes (132.6 vs 129.7 mL in the present setting and 96.3–138.4 mL in the quoted papers [12, 13]). Also, in the literature, the HoLEP technique provided similar enucleation times (66.4–95.8 min [14, 15]) and morcellation times (16.1–21.75 min [14, 15]) to the present plasma-button setting (74.9 and 16.5 min). Moreover, the quantities of resected tissue retrieved during HoLEP (77–93.7 g [16, 17]) and the initial prostate volumes (99–114.6 g [16, 17]) matched with our findings, thus emphasizing the virtually equivalent efficiency of the two types of enucleation.
Otherwise, the BPEP approach was characterized by reduced postoperative haematuria (2.9%) and blood transfusion (1.4%) rates in a similar manner to HoLEP (2.5%–4.8% [18, 19] and 1.2%–1.4% [20, 21]) compared with OP, both in the present series (12.9% and 8.6%) as well as in the literature (6.8%–29.3% [22, 23] and 12.7%–16.7% [24, 25], respectively). Consequently, conditions rather resembling bladder irrigation requirements were established for BPEP (2.9%) and HoLEP (3.5%–10.2% [15, 22]). The decreased mean haemoglobin drop associated with either the ‘button’ (1.7 g/dL) or the HoLEP (1.9–2.12 g/dL [26, 27]) also sustained the idea of a lower bleeding risk when drawing a parallel with open surgery (3.1 g/dL in our OP group and 2.8–3.15 g/dL in the published data [17, 27]).
Substantial advantages were determined concerning the catheterization period and hospital stay in BPEP cases (1.5 and 2.1 day) but also according to HoLEP trials (1.35–1.79 days [28, 29] and 1.3–2.9 days [17, 30], respectively) when facing a comparison with the OP arm in the present study (5.7 and 6.9 days) and related literature results (5–7 days [31, 32] and 6–9.2 days [13, 33]). Consequently, the shorter postoperative recovery, otherwise one of the main goals of the newly introduced BPH therapeutic approaches, seemed to be within the reach of the plasma enucleation procedure.
From the point of view of short-term adverse events, in this study recatheterization for acute urinary retention was significantly more frequent in transvesical prostatectomy patients (7.1% vs 1.4%), as also confirmed in other trials with regard to standard OP (7.6%–16.67% [23, 34]). This parameter appeared to be marked by a rather wide range of results when discussing the HoLEP-specific outcome and varied between 1.2%–3% [20, 28] and 7.8%–12.1% [27, 35]. Additionally, the rates of irritative symptoms (11.4% vs 7.1%) and urinary tract infections (2.9% vs 5.7%) were statistically similar for BPEP and OP. According to published data, the respective short-term complications were characterized by various and yet overall similar proportions when referring to HoLEP (9.4%–23.0% [22, 36] and 1.7%–5% [4, 15]) and transvesical prostatectomy (11.6%–41% [27, 34] and 10%–23% [13, 34]).
Further along the path of medium-term complications, similar rates were emphasized for the plasma-button technique and OP concerning bladder neck sclerosis (1.6% vs 1.6%), urethral strictures (3.1% vs 3.2%) and urinary incontinence (1.6% vs 1.6%). These findings were consistent with the available literature on HoLEP (1.3%–3.9% [19, 35], 2.1%–3.5% [15, 21] and 0.5%–5% [4, 36]) and OP (3.2%–3.3% [24, 31], 1.9%–3.3% [27, 31] and 0.7%–2.5% [13, 24]). Ultimately, the three therapeutic alternatives appear to benefit from virtually the same satisfactory safety profile, at least during the 12 months following the initial intervention.
Most importantly, the patients' comfort observed during the 1-year evaluation period can be considered as a substantial landmark in establishing the true viability of this new type of endoscopic technique. In this regard, at 1, 3, 6 and 12 months, similar results were determined among BPEP and OP patients concerning the IPSS (5.7 vs 5.9, 4.8 vs 4.7, 4.3 vs 4.4 and 4.1 vs 4.3) and QoL (1.6 vs 1.9, 1.3 vs 1.6, 1.1 vs 1.2 and 1.0 vs 1.2). Promising enough, according to published results, the already consecrated HoLEP displayed rather similar IPSS (5.2–8.6 [18, 30], 4.5–7.9 [15, 37], 2.8–6.5 [14, 19] and 3.9–7.6 [4, 15]) and QoL (1.4–2.7 [27, 37], 1.02–1.9 [15, 37], 0.97–1.4 [14, 36] and 0.8–1.2 [15, 38]) data at the respective time intervals. Moreover, while naturally acknowledging some variations, the available trials on OP generally followed the same pattern as the present study when referring to IPSS (4.7–10.6 [24, 27], 3.6–10 [17, 34], 2.8–9 [17, 34] and 2.8–8.4 [13, 27]) and QoL (1.3–2 [27, 34], 0.6–2 [27, 34], 1–1.34 [33, 34] and 1.26–1.6 [13, 31]).
While looking at the medium-term functional outcome of the plasma enucleation and transvesical procedures, similar Qmax values were provided at the 1-, 3-, 6- and 12-month check-ups subsequent to these techniques (24.1 vs 24.3 mL/s, 25.0 vs 24.9 mL/s, 25.6 vs 25.2 mL/s and 25.4 vs 25.1 mL/s). When referring to the respective urodynamic parameters specific for HoLEP, quite similar determinations were emphasized according to the published data at the respective follow-up examinations (17.8–26.6 mL/s [4, 27], 15.78–27.2 mL/s [28, 29], 17.8–29.9 mL/s [17, 21] and 20.9–26.16 mL/s [15, 37]). More so, the above-mentioned figures of our analysis favourably matched the OP related literature on the maximum flow rate registered during the first year after surgery (23.7–26.6 mL/s [17, 24], 14.5–25.5 mL/s [13, 27], 15.6–27.0 mL/s [17, 34] and 16.4–28.8 mL/s [13, 17]).
Finally, progress concerning the postoperative PVR did not show any significant difference between the BPEP and OP study arms (42.9 vs 38.6 mL, 31.6 vs 32.8 mL, 27.1 vs 26.7 mL and 21.4 vs 20.9 mL). In the light of the available trials on HoLEP (32.8–46.8 mL [15, 38], 25.5–32.4 mL [15, 21], 27–42.1 mL [4, 36] and 15–27 mL [29, 38]) and OP (17.5–60 mL [12, 32], 16.4–21 mL [13, 34], 12.5–92 mL [33, 34] and 9.12–12.6 mL [13, 31]), virtually similar prospects were achieved at the 1-, 3-, 6- and 12-month assessments.
Last, it was observed in the literature that the BPH minimally invasive treatment in general and the laser and electro-vaporization approaches in particular determine a serum PSA value reset to lower levels by comparison with preoperative features. Most importantly, such modifications were considered of substantial significance during the long-term follow-up of these patients . From this perspective, when attempting to elucidate the overall efficacy of the techniques, the PSA level decrease was similar in the BPEP and OP series of patients at the 6-month (90.6% vs 90.1%) and 12-month (91.1% vs 90.7%) measurements. The published studies dealing with HoLEP (86%–94.6% [19, 20]) as well as with OP (94% ) determined a quite similar PSA value reduction, thus confirming the efficacy of the plasma-button technique. More so in this regard, the TRUS evaluation of the postoperative prostate volume decrease was similar among BPEP (90.6%–91.1%) and OP (90.1%–90.7%) cases of the present study. Yet again, available data on both the HoLEP (82%–85.9% [26, 35]) and OP (89.5% ) were consistent with our findings as far as BPH tissue removal capabilities were concerned.
Future clinical research will be required in order to further clarify the long-term viability of this newly introduced large BPH treatment modality from the points of view of follow-up symptom scores, voiding parameters, late complications and adenoma tissue ablation effects. However, an optimistic perspective on the plasma-button may be outlined in the light of this initial randomized evaluation, which appears to confirm BPEP as a solid competitor for HoLEP and a dependable alternative for minimizing open surgery related morbidity while practically maintaining similar efficacy.
In conclusion, BPEP was found to represent a promising endoscopic approach in large BPH cases, presumably capable of challenging the ‘gold standard’ status of OP, in comparison with which it displayed satisfactory surgical efficiency and safety as well as similar BPH tissue removal capabilities. This perspective was supported by the results concerning the mean operation duration and resected tissue weight specific for the two treatment alternatives.
The plasma-button enucleation technique emphasized an overall significantly lower peri-operative morbidity and an improved postoperative recovery compared with standard OP. In terms of haemorrhagic risks, the substantially reduced postoperative haematuria, mean haemoglobin drop and blood transfusion rates confirmed the superior haemostatic capabilities of BPEP. Moreover, the significantly decreased catheterization period and hospital stay may constitute reliable arguments in favour of the clearly shorter convalescence period related to the plasma enucleation procedure.
Furthermore, BPEP patients benefited from a similar 12 months' outcome from the perspectives of follow-up symptom scores and voiding parameters when drawing a parallel with open surgery results, thus underlining the reliable viability of this type of approach. Additionally, a similar evolution of the PSA level and postoperative prostate volume was determined during the 1-year evaluation period, therefore confirming the practically equivalent BPH tissue removal effects of the plasma enucleation and OP treatment alternatives.
Conflict of Interest
Bogdan Geavlete received honoraria as a Speaker at Olympus Sponsored Symposia.