Urethral Strictures and Bipolar Transurethral Resection in Saline of the Prostate: Fact or Fiction?

Abstract

Purpose:

To compare the incidence of urethral strictures after monopolar transurethral resection of the prostate (TURP) and bipolar transurethral resection in saline (TURIS) for symptomatic benign prostatic hyperplasia.

Patients and Methods:

Between January 2005 and January 2009, 518 patients with symptomatic benign prostate hyperplasia underwent either monopolar or bipolar resection. In a randomized trial, the incidence of urethral strictures after both treatment modalities was analyzed.

Results:

Over 48 months, 255 patients were treated with conventional TURP and 263 patients with TURIS. Patient related, operation, and hospitalization characteristics were similar in both groups. After a mean follow-up of 32.1 months (range 50–7 months), the incidence of urethral strictures was 2.4% in the TURP group. After a comparable period of 31.4 months (range 50–7 months), the incidence in the TURIS group was 1.5%. No statistically significant difference was obtained (P = 0.539). These values were compared with the results of other randomized controlled trials with the same or other bipolar technology. No statistically significant difference in urethral structures was noticed between monopolar and bipolar resections (P = 0.739).

Conclusions:

With a stricture incidence of 1.5%, bipolar transurethral prostate resection has a low stricture rate, comparable with monopolar TURP (2.4%).

Introduction

M onopolar transurethral resection of the prostate (TURP) is the gold standard for operative management of symptomatic benign prostatic hyperplasia (BPH).¹ The efficacy and morbidity of new techniques and technologies should be compared with TURP.²

Bipolar resection of the prostate is a slightly different concept of TUR technology. By incorporating both the active and return poles on the same electrode,³ a conductive fluid medium (physiologic saline) can be used instead of the conventional nonconductive irrigation fluid (glycine, sorbitol, and mannitol).

Many randomized controlled trials were conducted to evaluate perioperative and postoperative morbidity as well as the final outcome of bipolar resections with Gyrus PlasmaKinetic and Olympus transurethral resection in saline (TURIS) systems.² They all lead to the conclusion that bipolar technology has similar clinical efficacy as monopolar TURP. Furthermore, in all randomized controlled trials, neither life-threatening hyponatremia nor TUR syndrome was observed, which leads to the conclusion that bipolar resections are safer.²

Other concerns arise about the incidence of urethral injuries. We compare the incidence of urethral strictures after bipolar TURIS vs conventional monopolar TURP in patients with moderate to severe bladder outlet obstruction from BPH in a randomized trial.

Patients and Methods

Patient data

Between January 2005 and January 2009, after ethics committee approval of the study protocol, all men with moderate and severe bladder outlet obstruction from BPH were included in a single center, unblinded study. Oral informed consent was obtained. The minimal inclusion criteria for entry were an International Prostate Symptom Score of 13 or more, quality-of-life index of 3 or more, and maximal urinary flow rates below 15 mL/s. Exclusion criteria were neurogenic bladder, prostate cancer, previous prostatic or urethral surgery, and bladder stones.

The diagnostic evaluation included a history, physical and digital rectal examinations, urinalysis and urine culture, serum electrolytes tests, renal function test, full blood cell count, prostate specific antigen determination, uroflowmetry, and abdominal ultrasonographic measurement of postvoid residual urine volume. Transrectal ultrasonography was performed to measure the prostate volume preoperatively.

After initial cystoscopy and examination with the patient under anesthesia, the patient was randomized to conventional monopolar TURP or bipolar TURIS by drawing a closed envelope. The two procedures were performed with intermittent glycine or saline irrigation and with the patient under general or spinal anesthesia. At the end of the procedure, a 22F three-way Foley catheter with a closed drainage system was inserted. All patients were treated postoperatively with continuous saline bladder irrigation until there was no more macroscopic hematuria. Full blood cell count and serum electrolytes levels were determined immediately after surgery in all patients. Two urologists in training managed the hospital stay and made the decision to discharge the patient from the hospital.

The patients were reassessed at 3-month intervals in the outpatient clinic. Urinalysis, uroflowmetry, and 3-mn/h uterals abdominal ultrasonographic measurement of postvoid residual urine volume were performed to follow the urinary stream. In patients with a typical flow pattern of a stricture or peak flow less than 10 cm/s, cystoscopy or retrograde urethrography were performed to exclude urethral strictures.

Equipment

A standard Olympus resectoscope and an Olympus UES-40 SurgMaster electrical current generator were used for TURP and TURIS. TURP was performed with a standard 24F resectoscope and standard loops using 175 W cutting power and 75 W coagulation power. TURIS was performed using a 24F resectoscope with bipolar electrodes set at 270 W for cutting and 75 W for coagulation.

Statistics

All statistical tests performed were two-sided and at the 5% level of significance. The two groups were compared using the independent t test. Complications such as urethral strictures were processed by the Fisher exact test. The P values obtained were very similar to the chi-square test with continuity correction. SPSS version 17.0 was used to perform the tests.

Results

Over a 48-month period, 518 patients with symptomatic BPH were treated surgically by endoscopic resection: 255 by conventional monopolar TURP and 263 by bipolar TURIS.

Patient related, operation, and hospitalization characteristics of both groups are reported in Table 1.

Table 1.

Characteristics of Two Groups

Variables	Monopolar TURP Mean (±SD)	Bipolar TURIS Mean (±SD)	P value	95% confidence interval of the difference
Age (yr)	72.4 (±9.0)	72.5 (±9.2)	0.816	(−1.385, 1.758)
Prostate (cc)	53.9 (±23.6)	45.0 (±18.3)	0.001	(−14.032, −3.826)
Prostate adenoma (cc)	32.1 (±15.5)	25.7 (±11.8)	0.000	(−9.742, −3.118)
Operative time (min)	50.9 (±22.2)	52.1 (±22.5)	0.532	(−2.675, 5.171)
Resection weight (g)	19.5 (±15.1)	18.0 (±11.6)	0.194	(−3.936, 0.801)
Resection speed (g/min)	0.40 (±0.33)	0.37 (±0.22)	0.154	(−0.086, 0.014)
Catheterization time (d)	1.64 (±0.86)	1.61 (±1.33)	0.815	(−0.216, 0.170)
Hospital stay (d)	3.89 (±3.18)	3.72 (±2.62)	0.773	(−0.650, 0.483)

TURP = transurethral resection of the prostate; TURIS = transurethral resection in saline; SD = standard deviation.

Men in the TURP group were 48 to 93 years old (mean age ± SD 72.4 ± 9.0). The patients treated by TURIS were 50 to 91 years old (mean age ± SD 72.5 ± 9.2).

The measured volumes of both the prostate, 45.0 ± 18.3 cc (16–100) in the TURIS group and 59.9 ± 23.6 cc (17–120) in the TURP group, and the adenoma, 25.7 ± 11.8 cc (6–59) in the TURIS group and 32.1 ± 15.5 cc (7–80) in the TURP group were smaller in the TURIS group. These differences had no impact on surgical parameters such as resection time, resection weight, and resection speed.

The mean operative time was 50.9 ± 22.2 minutes (15–134 min) in the TURP group and 52.1 ± 22.5 minutes (15–130 min) in the TURIS group. Our policy is to keep resection time as short as possible and not to exceed 60 minutes. Nevertheless, 74 of 255 (29%) conventional resections and 73 of 263 (28%) TURIS procedures needed more than 1 hour.

The amount of prostatic tissue resected was 19.5 ± 15.1 g (3–60.6 g) in the TURP group and 18.0 ± 11.5 g (3.2–65.2 g) in the TURIS group.

Both the resection time and the weight of the removed tissue did not differ significantly (Table 1).

The indwelling catheter was removed after 1.64 ± 1.33 days (1–6 d) in the TURP group and after 1.64 ± 0.85 days (1–17 d) in the TURIS group (P = 0.815). There was no statistically significant difference in the duration of their hospital stay. TURP patients were discharged after an average of 3.89 ± 3.2 days (1–33 d) and TURIS patients after an average of 3.72 ± 2.6 days (1–20 d).

The follow-up period was 32.1(±11.6) months in the TURP group and 31.4 (±12.2) months in the TURIS group (P = 0.512). Table 2 lists the incidence of urethral strictures after TURP and TURIS. All of these patients needed a second intervention. Reoperations consisted of visual urethrotomy in six patients and external meatotomy in two patients. Repeated dilatation was performed in two patients.

Table 2.

Urethral Strictures

Variables	Monopolar TURP N (%)	Bipolar TURIS N (%)	P value
Meatal urethra	1 (0.4%)	1 (0.4%)	1.000
Penile urethra	2 (0.8%)	1 (0.4%)	0.618
Bulbar urethra	1 (0.4%)	1 (0.4%)	1.000
Membranous urethra	2 (0.8%)	1 (0.4%)	0.618
Total	6 (2.4%)	4 (1.5%)	0.539

TURP = transurethral resection of the prostate; TURIS = transurethral resection in saline.

Discussion

Voiding difficulties because of BPH can be managed by medical treatments or surgical procedures. Regarding the size of the prostate, the prostate adenoma is surgically approached transurethrally or transabdominally. Transurethral incision of the prostate is an effective treatment option for small prostates. Transurethral resections, transurethral laser therapies, and abdominal approaches are reserved for medium and larger prostates.

The conventional monopolar TURP is the gold standard to manage medium-sized BPH. New techniques and technologies, such as holmium laser enucleation, photoselective vaporization, and thulium laser resection, bipolar resection, bipolar vaporization, and bipolar enucleation should be compared with this reference standard on the basis of efficacy, morbidity, mortality, and economic impact.^4,5

Although its basic concept is the same, bipolar resection of the prostate differs slightly from TURP only in the energy source and the irrigating fluid.

The ideal irrigant for endoscopic resections would be a user friendly, nonconductor medium that does not interfere with diathermy, has a high degree of translucency, an osmolality similar to that of serum, and causes minimal side effects when absorbed. Monopolar transurethral surgery has to be performed in nonhemolytic, hypo-osmolar irrigating fluids such as glycine, sorbitol, or mannitol. When high volumes of these fluids are absorbed, a TUR syndrome may follow. In a bipolar setting, physiologic saline can be used. This is obviously a more physiologically appropriate solution because it can be administered intravenously with minimal side effects.

In monopolar electrosurgery, the electrical current runs through the body from the active electrode (connected to the resectoscope loop) toward the large-surfaced grounding pad that is attached to the skin. In bipolar electrosurgery, the electricity runs between an active and a return pole, both part of the resectoscope.³ The energy completes the circuit between the two poles at the site of surgery. Five different types of bipolar resection devices have been described in the medical literature: PlasmaKinetic system (Gyrus), Vista Coblation/controlled tissue resection system (ACMI), transurethral resection in saline (TURIS) system (Olympus), Karl Storz, and Wolf.⁶ Randomized controlled studies with Gyrus, Vista, and TURIS have been reported thus far. The Vista has been withdrawn from the market since 2006.⁶

Each system is characterized by minor technical differences in how it delivers the bipolar current.

In the PlasmaKinetic system, the resection loop is the active electrode, and the passive electrode is situated in the distal part of the resection loop.

In the Vista system, current runs between the active and passive electrode arranged as parallel loops on one device.

The active electrode of the TURIS system is a single cutting loop, and the return electrode is incorporated in the sheath. The electric current passes from the resection loop in saline and returns through the sheath that is double protected to prevent leakage. Issa⁷ criticized the so-called bipolar TURIS system and called it a halfway technology. Indeed, the TURIS system does not meet the definition of bipolarity according to the criteria set by the International Electrosurgical Commission. This requires both the active and return electrodes to be attached to a single support system,³ and the electric circuit is completed with the full energy returning back to the generator through the urethra. TURIS offers “pseudo-bipolar” functionality while using physiologic saline irrigation to decrease the risk of hyponatremia and TUR syndrome.

The perioperative and postoperative morbidity and the final outcome of bipolar resections with Gyrus PlasmaKinetic, Olympus TURIS, and Vista systems were evaluated in randomized controlled trials.² It was concluded that bipolar technology shares similar clinical efficacy to monopolar TURP. Furthermore, no cases of life-treating hyponatremia and TUR syndrome were observed, leading to the conclusion that bipolar resections are safer.²

Concern was raised by Reich⁸ about postoperative strictures. This late complication could mean a drawback for bipolar resections.

Meatal and urethral strictures are major late complications after conventional monopolar TURP. The incidence of urethral strictures after monopolar resection varies between 2.2% and 9.8%.⁴ The location of the stricture is related to its cause.⁹ Meatal strictures usually occur by inappropriate accordance between the thickness of the instrument and the meatal diameter. Urethral strictures are caused by insufficient lubrication. Good prevention is achieved by frequent application of large amounts of lubricants with appropriate conductivity.

TUR inevitably leads to mechanical and thermal stress of the urethra. Mechanical stress may result from an oversized resectoscope, inappropriate axial and rotating movements of the resectoscope, longer operative time, and longer catheterization time.¹⁰ Both with conventional monopolar TURP and bipolar TURIS, leakage of electric current can provoke stenosis. Thermal damage to the urethra is also caused by internal high-frequency current during TUR, a specific risk with TURIS in which the passive electrode is incorporated into the outer sheath. High cutting current should therefore be avoided in both techniques.

Today, most randomized controlled trials on bipolar technology do not mention longer operative times (Table 3). Tefekli and associates¹¹ and Erturhan and colleagues,¹² on the contrary, reported statistically significant lower operative time with Gyrus. Only Rose and coworkers¹³ and Michielsen and colleagues¹⁴ reported a longer operative time with TURIS. This last study, however, was criticized by Ho and Lim¹⁵ for the heterogeneous experience of its operators. Both studies also did not report on late complications. In this more extensive clinical study, we did not observe any further statistically significant difference in operative time (P = 0.532).

Table 3.

Operative Time And Catheterization Time in Randomized Controlled Trial Who Reported on Urethral Strictures

	Operative time			Catheterization time
Study	Monopolar (min)	Bipolar (min)	P value	Monopolar(d)	Bipolar(d)	P value
Tefekli¹¹	57.8	40.3	0.000	3.8	2.3	0.000
Singh et al¹⁷	36.9	39.3	0.961	3.4	2.5	0.022
Seckiner¹⁶	52.9	52.9	0.835	3.1	3.1	0.981
Erturhan¹²	57	36	0.000	4.5	3	0.000
Ho et al¹⁹	58	59	0.769	NA	NA	NA
Bhansali²¹	NA	NA	NA	1.6	0.8	0.000
Autorino²⁰	53	49	0.070	NA	NA	NA
Michielsen¹⁴	50.85	52.09	0.532	1.6	1.6	0.815

In most randomized clinical trials that report urethral strictures and postoperative catheterization time after TUR or TURIS, patients who underwent TURIS had shorter catheterization times (Table 3). Only in the study of Seckiner and coworkers¹⁶ and this present study are no statistically significant differences in catheterization time observed.

The main drawback of bipolar resections is the higher cutting current, 270 W compared with 175 W in conventional monopolar techniques. This high-frequency current is a potential traumatizing agent for the urethra.

Bipolar resection is associated with a higher incidence of urethral strictures, as reported in several randomized controlled trials.^{11,12,16

–19} Because each bipolar technique has a minor different technique for delivery of electric current, each technique should be evaluated separately.

Five randomized controlled trials report on the incidence of urethral strictures with the bipolar Gyrus system; all used a 27F resectoscope. The incidence of urethral strictures (4.7%) did not statistically differ significantly (P = 0.828) compared with the incidence after conventional monopolar resections (3.9%)(Table 3). The follow-up period ranged between 12 months^12,16 and 48 months.²⁰

A point of concern with TURIS technology is that the neutral electrode is incorporated in the outer sheath of the resectoscope. Therefore, any leakage may burn the urethra and possibly cause urethral strictures. The manufacturer, however, has demonstrated that there are no signs of electrical leakage.¹⁹

Two randomized clinical trials focused on the incidences of urethral strictures (Table 4). Ho and associates¹⁹ used a 26F resectoscope, and follow-up was 12 months. We used a 24F resectoscope, and mean follow-up was 31.4 months in the TURIS group, with a maximum of 50 months. No statistical difference in the incidence of urethral strictures was observed with the TURIS technique (P = 1.000) (Table 4).

Table 4.

Urethral Strictures in Randomized Controlled Trial

Study	Monopolar N/Total (%)	Bipolar N/Total (%)	P value
Gyrus technology
Tefekli¹¹	1/47 (2.1%)	2/49 (6.1%)	1.000
Seckiner¹⁶	1/24 (4.2%)	2/24 (8.3%)	1.000
Erturhan¹²	2/120 (1.7%)	2/120 (1.7%)	1.000
Bhansali²¹	4/34 (11.7%)	5/33 (14.7%)	0.734
Autorino²⁰	2/31 (6.4%)	1/32 (3.1%)	0.613
TURIS technology
Ho¹⁹	1/52 (1.9%)	3/48 (6.3%)	0.348
Michielsen	6/255 (2.4%)	4/263 (1.5%)	0.539
VISTA technology
Singh¹⁷	0/30 (0.0%)	1/30 (3.3%)	1.000
Total	17/594 (2.9%)	20/599 (3.3%)	0.739

Singh and colleagues¹⁷ reported on their experience with Vista. They used a 25.5F resectoscope and found one case of urethral stricture in the bipolar resection group. This was during a very short follow-up of only 3 months, however.

All bipolar techniques together cause an average incidence of urethral strictures of 3.3%. This is statistically not significantly different from the incidence (2.9%) in the conventional monopolar TURP group (P = 0.739) (Table 4).

Conclusions

Although there are many concerns about the possible traumatizing impact on the urethra of the higher cutting current of 270 W in bipolar TURs, the incidence of urethral strictures seems acceptable. The bipolar TURIS is as safe for the urethra as the conventional monopolar TUR system.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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