prostatic stents for the treatment of benign prostatic hyperplasia

a report by

D r M M v a n D i j k and P r o f e s s o r J J M C H d e l a R o s e t t e

Department of Urology, Academic Medical Center, University of Amsterdam

I n t r o d u c t i o n

Benign prostatic hyperplasia (BPH) is a non-malignant enlargement of the prostate and may leadto lower urinary tract symptoms due to bladderoutlet obstruction. It is a common condition inageing men and it is well established that theincidence is increasing with age.1,2 Since the numberof ageing males in Western society is multiplying, theprevalence of BPH will increase.

Previously, the treatment options for BPH comprisedmainly surgical resection of the prostate. For manyyears, transurethral resection of the prostate (TURP)was the main treatment for moderately enlargedprostates. After this operation, symptom scoresdecrease and maximal urinary flow rates increasesubstantially.3 Although the surgical techniques haveimproved and morbidity rates have decreased over theyears, TURP is not a complication-free intervention.Complications may include intraoperative and post-operative blood loss, urethral or bladder neckstrictures, urinary incontinence, retrogradeejaculation, urinary tract infection and epididymitis.4,5

Besides this, patients with serious comorbidity maynot be candidates for surgical intervention.

For those patients with contraindications to surgeryor anaesthesia, several other therapeutic options havebecome available in the past decades. These includemedical therapy with alpha-blockers (α-blockers),6

anti-androgens7 or 5α-reductase inhibitors8 andminimally invasive tissue ablative therapy such astransurethral microwave therapy (TUMT),9

transurethral needle ablation10 and visual laserablation of the prostate (VLAP).11 A common sideeffect of these minimally invasive methods is acuteurinary retention, as a result of thermally inducedoedema. A promising non-tissue-ablating alternativethat has gained increasing attention is the techniqueof intraprostatic stenting. This simple techniqueallows rapid alleviation of symptoms, whilecircumventing surgical or pharmaceuticalintervention. This article provides a conciseoverview of the available literature on prostatic stentsand discusses the applicability of both temporary andpermanent stents in the treatment of BPH.

P r o s t a t i c S t e n t s

The use of an endoprosthesis to maintain luminalpatency is a well-established concept used in a varietyof surgical settings including cardiovascular andgastrointestinal pathologies. The use of stenting theprostatic urethra to relieve obstruction due toprostate enlargement was first described in 1980.12 Inthe search for the ideal stent, a range of differenttypes of stents have been developed and investigatedin clinical studies since. The ideal stent should beeasy to insert and position under local anaesthesia. Itcan be inserted blindly or with the help of acystoscope. When positioned, the stent should notextend beyond the prostatic urethra into the bladder,nor should it be able to migrate towards the bladder.Immediate, spontaneous voiding should be allowed,while maintaining continence. No local reaction orencrustation should occur. Furthermore, it should beeasy to remove the stent if necessary. Finally, thestent should be relatively inexpensive.

Over the past years, both temporary and permanentapplication of prostatic stents as a solution for bladderoutlet obstruction has been investigated. A majorcharacteristic of permanent stents is that they allowingrowth with eventual complete epithelialisation. Incontrast, temporary stent design prevents epithelialingrowth and these devices are thus easily removable.In the following sections, the use of temporary andpermanent stents will be discussed.

P e rman e n t S t e n t s

Permanent stents are intended as a definite treatmentof symptomatic BPH. They can be applied inpatients with serious comorbidity who are unfit formajor surgery, or in patients unwilling to undergosurgery. A key feature in permanent stents is thatthey allow tissue ingrowth, which results in the stentbeing permanently embedded in the wall of theurethra. This crucial epithelialisation should preventinfection, stent migration and deposition of urinarycrystals on the stent. A disadvantage of this process isthat the tissue response might result in luminalnarrowing. Besides this, the ingrowth may make itdifficult to remove the stent if indicated.

Pros ta t i c S tent s in the Treatment o f Ben ign Pros ta t i c Hyperp las ia

B U S I N E S S B R I E F I N G : G L O B A L S U R G E R Y 2 0 0 3

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R e s u l t s

Several different permanent stents have beendeveloped, such as Memotherm and UroLume®; themost experience, however, has been gained with theUroLume stent (see Figure 1).

The UroLume endoprosthesis is a self-expandablewoven tubular mesh that maintains its position in theurethra by outward external pressure and thusmaintaining the patency of the prostatic urethra.13 Itsefficacy was investigated in several studies with afollow-up period ranging from 12 to 24 months.Following insertion, 92% to 96% of the patients wereable to void satisfactorily. The symptom scores wereshown to decrease, the maximum urinary flowincreased and the post-void residual volume decreasedafter stent insertion.13–15 Complications include:frequency and urgency during two to 12 weeks afterimplantation in almost all patients, which mostlyresolved spontaneously or with anticholinergic medi-cation; haematuria (6% to 14% of the patients); pain inperineal area for a period of two weeks (2% to 13%);urinary tract infection (14% to 16%); and antegradeejaculation (0% to 17%). Excessive growth of prostaticepithelium causing obstruction was reported in 2% to3.3% of the patients. After 12 months the majority ofthe stents were covered with epithelium. Encrustationwas found in up to 46% of the patients.13–15 After twoyears, explantation was required in 13% of the patients.The reasons for explantation were migration (29%),recurrent obstruction (29%), encrustations (12%),persistent irritative voiding symptoms (12%), perinealdiscomfort (12%) and urinary incontinence (6%).13 Inanother study, with a follow-up period of five years,35% of the stents were removed due to migration,contraindications for prostatic stents (middle lobe),poor positioning of the stent and patients’ request. Inthe patients who completed the follow-up, the resultswere satisfactory.16

The Memotherm is a heat-expandable permanentstent, made from a nickel-titanium woven wire. Theresults of studies conducted by Williams, et al. andGesenberg, et al. were disappointing.17,18 Successrates were low, and complications, such as recurrentinfections and urge symptoms, urothelial hyperplasiaand incontinence, occurred frequently.

T empo r a r y a n d B i o d e g r a d a b l e S t e n t s

Temporary stents are designed primarily for short-term use in the treatment of symptomatic BPH, for aduration of six months to three years. They can act asan alternative to an indwelling catheter in high-riskpatients considered unfit for surgery or in patientsawaiting surgery. Moreover, temporary stents can beemployed to prevent post-operative urinary retentioncaused by oedema after various thermotherapy

treatments such as TUMT.16 Temporary stents aremade of non-absorbable material, which preventsepithelial ingrowth and therefore allows easy removal.However, this may lead to unintended migration.Biodegradable stents are also classified as temporarystents. These stents break down slowly into smallfragments, which are excreted through the urethraover time, so no explantation procedure is required.A possible disadvantage of biodegradable stents is thatthe fragments may cause obstruction of the urethra.

R e s u l t s

Temporary stents can essentially be divided intothree groups: spiral stents (first and secondgeneration); polyurethane stents; and biodegradablestents (see Table 1). Several studies have evaluated theclinical efficacy of these different types of temporarystents. A complete outline of the literature on all ofthe different types of stents is beyond the scope ofthis article. This section reviews the findings ofstudies addressing the applicability of a few differentstents either for the purpose of managing BPH inhigh-risk patients or to prevent urinary retentionafter thermotherapy treatments.

Temporary Stents as a Treatment for BPH in

Patients Unf it for Surgery

The first-generation spiral stents are based on Fabian’soriginal design of the Urospiral® (see Figure 1). They

Figure 1

Table 1: Temporary Stents

Spiral stents

First generation Urospiral

Prostakath

Second generation Prostacoil

Endocare

Polyurethane Intraurethral catheter (Nissenkorn)

stents Barnes

Trestle

Biodegradable self-reinforced polyglycolic acid spiral

stents self-reinforced poly-DL-lactic acid spiral


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Reference Section

are made of a coiled wire of stainless steel, with orwithout gold coating, and are non-expandable. Theinitial results were encouraging, but longer-term dataindicated success in only a few patients. In differentstudies on the Prostakath® and Urospiral stents, theoverall success rates (defined as stent left in situ andfunctioning) vary from 55% to 66%.19–21 Manyproblems were encountered using this type of stent inthe treatment of symptomatic BPH. Highcomplication rates such as migration (11% to 17%),retention (11% to 31%) and incontinence (10% to37%) were reported.19–22 Many patients complained ofmoderate to severe irritative symptoms such asurgency and frequency (50% to 57%)19,22 andencrustation rates were high (17% to 31%).20,21

Spiral stents of the second generation weredeveloped in an attempt to overcome the problems

associated with the first-generation spiral stents,such as migration and encrustation. They are madeof nitinol and are either self-expandable(ProstaCoil®) or expandable when heated withwarm water after insertion. In the few studies onthese stents, satisfactory success rates have beenreported (75% to 83%).23 Migration occurred in13% to 17% of the patients,23,24 retention in 10%23

and incontinence in 3% to 8%.23–24 Frequency andurgency complaints were quite common,18 butencrustation rates were low.23,24

Polyurethane stents are also known as intraurethralcatheters (see Figures 5 and 6). Different designs ofthese stents made of polyurethane have becomeavailable. Studies on the use of the Nissenkornintraurethral catheter and the Trestle™ stent (alsocalled prostatic bridge catheter) reported success rates(defined as being able to void without incontinence)of between 81% and 84%.25,26 Migration of the stentoccurred in 10% to 21% of the cases and complaintsof urgency were reported in only 7% to 10% of thepatients. Encrustation rates remained low.25–27

Biodegradable stents are composed of polyglycolic acidand are self-expanding at body temperature.Degradation into glycolic acid occurs throughhydrolysis and the eventual end-products are water andcarbon dioxide. The use of the self-reinforced poly-L-lactide biodegradable (SR-PLLA) stent was assessed inrabbits.28 Throughout the entire follow-up period, theurethra was found to be patent in all subjects and noobstructive inflammatory tissue reaction occurred. Aclinical pilot study on the SR-PLLA stent as atreatment of acute urinary retention from BPHshowed some promising results, with a success rate of73%.29 Surprisingly, in the pilot study that followed thefirst study, the failure rates were reported to be veryhigh. As a result of insufficient therapeutic response anduncontrolled breakdown of the stent, over 60% of thepatients discontinued participation in the study.30

Temporary Stents to Prevent Urinary

Retent ion after Thermotherapy

After thermotherapy treatments such as TUMT andVLAP, urinary retention is a very common sideeffect. It is caused by post-operative oedema and itoften necessitates catheterisation. After TUMT, forexample, 12% to 36% of patients have been reportedto require catheterisation for as long as one week inthe majority and longer than one month in someindividuals.13 In the past, an indwelling or suprapubiccatheter was placed as a solution for retention;disadvantages of which are inconvenience for thepatient and a high risk of infection. Recently, thefeasibility of using different types of temporary stentsfor preventing retention after various thermotherapytreatments has gained increasing attention. A numberof studies on the use of polyurethane stents and

Figure 2

Figure 3

Figure 4


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biodegradable stents during the acute recovery periodafter thermotherapy have shown promising results.

A polyurethane catheter (the prostatic bridgecatheter) was reported to be effective in preventingurinary retention after TUMT. Two weeks afterTUMT, improvements in mean peak flow rate,International Prostate Symptom Score (IPSS) andquality-of-life score in patients in whom a prostaticbridge catheter was inserted were significantly higherthan in patients who did not receive a stent. In theTUMT-only patients, urinary retention was noted in11%, whereas in none of the patients with a stentretention was urinary retention reported. Migrationof the stent occurred in 5.6% and the stent becameobstructed due to clot formation in 5.6% of thepatients. Other adverse events such as urinary tractinfection occurred infrequently.31,32

The use of a biodegradable stent, the self-reinforcedpolyglycolic acid stent, after VLAP was investigatedin several studies.33–35 Voiding began one to two dayspost-operatively in 74% to 100% of the patients,whereas only 35% of the patients without a stentvoided within two days post-operatively. In 9%,urinary retention occurred later due to earlydegradation of the stent. Approximately 50% of thepatients described a transient decreased urinary flowafter three to four weeks, probably due todegradation of the stent. Urine cultures were positivein 14% to 22% of the stented patients, comparedwith 30% in the patients without a stent.30,31 In anattempt to overcome the problem of pre-termdegradation, a stent with a longer degradation time,the self-reinforced poly-DL-lactic acid spiral, wasdeveloped. Comparable results were found; 82% ofthe patients were able to void within two days andno pre-term degradation occurred.35

Con s i d e r a t i o n s

Not every patient is a suitable candidate for prostaticstent placement. Patients with a middle lobe or abladder neck stricture may not benefit from aprostatic stent. Also, patients with either a very shortor a very large prostate fossa may be poor candidatesfor a stent. In addition, patients with serious bleedingdisorders or poor bladder function should not begiven a prostatic stent.

Con c l u s i o n

Since the introduction of the first prostatic stent in1980, several different stents have become availableand various indications have been investigated.

Permanent stents have a wide range of indicationsand a high clinical efficacy. However, side effects areserious and occur frequently. Moreover,

explantation rates are very high and removal of thesestents can be difficult, therefore permanent stentingof the prostate has not gained wide acceptance in theurologic community.

Temporary stents can be used as an alternative to anindwelling catheter for short-term relief of prostaticobstruction, either in patients with contraindicationsfor surgery or in patients who are awaiting surgery ordo not wish to undergo surgery. They allow normalvoiding and are easily inserted and removed in anout-patient setting. However, they carry aconsiderable risk of complications such asencrustation and migration of the stent.

Figure 5

Figure 6


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Reference Section

The most promising application of temporary stentsis prevention of urinary retention as a result ofthermally induced oedema after thermotherapy.Most studies have shown satisfactory results; transienturinary retention and voiding difficulty after theseprocedures seem to be better managed with stentsthan with an indwelling catheter.

Together, the available literature confirms that the

concept of maintaining luminal patency by stenting theprostate in symptomatic BPH patients is a viable one.

Further research and long-term follow-up is requiredto optimise the technique and minimise side effects.Future stent designs deserve special attention to meetthe specifications of the ideal stent concept:uncomplicated insertion, minimal in situ discomfortand easy removal. ■

R e f e r e n c e s

1. S J Berry, D S Coffey, P C Walsh and L L Ewing, “The Development of Human Prostatic Hyperplasia withAge”, J. Urol., 132 (1984), pp. 474–479.

2. K M Verhamme, J P Dieleman, G S Bleumink, J van Der Lei, M C Sturkenboom, W Artibani, B Begaud, RBerges, A Borkowski, C R Chappel, A Costello, P Dobronsky, R D Farmer, F Jimenez Cruz, U Jonas, KMacRae, L Pientka, F F Rutten, C P van Schayck, M J Speakman, M C Sturkenboom, P Tiellac, A Tubaro, GVallencien, R Vela Navarrete, Triumph Pan European Expert Panel, “Incidence and Prevalence of Lower UrinaryTract Symptoms Suggestive of Benign Prostatic Hyperplasia in Primary Care – The Triumph Project”, Eur. Urol.,42 (2002), pp. 323–328.

3. J H Wasson, D J Reda, R C Bruskewitz, J Elinson, A M Keller and W G Henderson, “A Comparison ofTransurethral Surgery with Watchful Waiting for Moderate Symptoms of Benign Prostatic Hyperplasia”, TheVeterans Affairs Cooperative Study Group on Transurethral Resection of the Prostate, N. Engl. J. Med., 332(1995), pp. 75–79.

4. W K Mebust, H L Holtgrewe, A T K Cocket and P C Peters, Writing Committee, “Transurethral Prostatectomy:Immediate and Postoperative Complications: A Cooperative Study of 143 Participating Institutions Evaluating3,885 Patients”, J. Urol., 141 (1989), pp. 243–247.

5. P G Borboroglu, J K Kane, J F Ward, J L Roberts and J P Sands, “Immediate and Postoperative Complications ofTransurethral Prostatectomy in the 1990s”, ibid., 162 (1999), pp. 1,307–1,310.

6. R S Kirby and J L Pool, “Alpha Adrenoceptor Blockade in the Treatment of Benign Prostatic Hyperplasia: Past,Present and Future”, Br. J. Urol., 80 (1997), pp. 521–532.

7. M Caine, S Perlberg and R Gordon, “The Treatment of Benign Prostatic Hypertrophy with Flutamide (SCH:13521): A Placebo-controlled Study”, J. Urol., 114 (1975), pp. 564–568.

8. G J Gormley, E Stoner, R C Bruskewitz, J Imperato-McGinley, P C Walsh, J D McConnell, G L Andriole, JGeller, B R Bracken, J S Tenover, et al., “The Effect of Finasteride in Men with Benign Prostatic Hyperplasia”,The Finasteride Study Group, N. Engl. J. Med., 327 (1992), pp. 1,185–1,191.

9. D L Floratos, L A Kiemeney, C Rossi, B B Kortmann, F M Debruyne and J J de la Rosette, “Long-term Follow-up of Randomized Transurethral Microwave Thermotherapy Versus Transurethral Prostatic Resection Study”, J.Urol.,165 (2001), pp. 1,533–1,538.

10. A R Zlotta, X Giannakopoulos, O Maehlum, T Ostrem and C C Schulman, “Long-term Evaluation ofTransurethral Needle Ablation of the Prostate (TUNA) for Treatment of Symptomatic Benign Prostatic Hyperplasia:Clinical Outcome up to Five Years From Three Centers”, Eur. Urol., 44 (2003), pp. 89–93.

11. D L Floratos, G S Sonke, E A Francisca, L A Kiemeney, F M Debruyne and J J de la Rosette, “Long-termFollow-up of Laser Treatment for Lower Urinary Tract Symptoms Suggestive of Bladder Outlet Obstruction”,Urology, 56 (2000), pp. 604–609.

12. K M Fabian, “Der Intraprostatische “Partielle Katheter” (Utologische Spirale)”, Urologe, 19 (1980) A, pp.236–239.

13. J E Oesterling, S A Kaplan, H B Epstein, A J Defalco, P K Reddy and M B Chancellor, “The North AmericanExperience with the UroLume Endoprosthesis as a Treatment for Benign Prostatic Hyperplasia: Long-term Results”,The North American UroLume Study Group, Urology, 44 (1994), pp. 353–362.

14. E Milroy and C R Chapple, “The UroLume Stent in the Management of Benign Prostatic Hyperplasia”, J. Urol.,150 (1993), pp. 1,630–1,635.

15. G Guazzoni, F Bergamaschi, F Montorsi, P Consonni, L Galli, V Matozzo and P Rigatti, “Prostatic UroLumeWallstent for Benign Prostatic Hyperplasia Patients at Poor Operative Risk: Clinical, Uroflowmetric andUltrasonographic Patterns”, ibid., pp. 1,641–1,646 [discussion pp. 1,646–1,647].

16. M I Anjum, R Chari, A Shetty, M Keen and J H Palmer, “Long-term Clinical Results and Quality of Life AfterInsertion of a Self-expanding Flexible Endourethral Prosthesis”, Br. J. Urol., 80 (1997), pp. 885–888.

17. G Williams and R White, “Experience with the Memotherm Permanently Implanted Prostatic Stent”, ibid., 76(1995), pp. 337–340.

18. A Gesenberg and R Sintermann, “Management of Benign Prostatic Hyperplasia in High Risk Patients: Long-termExperience with the Memotherm Stent”, J Urol., 160 (1998), pp. 72–76.

19. Z Braf, J Chen, M Sofer and H Matzkin, “Intraprostatic Metal Stents (Prostakath and Urospiral): More Than 6Years’ Clinical Experience with 110 Patients”, J. Endourol., 10 (1996), pp. 555–558.

20. J Nordling, H Ovesen and A L Poulsen, “The Intraprostatic Spiral: Clinical Results in 150 Consecutive Patients”,J. Urol., 147 (1992), pp. 645–647.

21. P Rosenkilde, J F Pedersen and H H Meyhoff, “Late Complications of Prostakath Treatment for Benign ProstaticHypertrophy”, Br. J. Urol., 68 (1991), pp. 387–389.

22. D Yachia, “Temporary Metal Stents in Bladder Outflow Obstruction”, J. Endourol., 11 (1997), pp. 459–465.23. M J Perry, A J Roodhouse, A B Gidlow, T G Spicer and B W Ellis, “Thermo-expandable Intraprostatic Stents in

Bladder Outlet Obstruction: An 8-year Study”, BJU Int., 90 (2002), pp. 216–323.24. D Yachia, M Beyar and I A Aridogan, “A New, Large Calibre, Self-expanding and Self-retaining Temporary

Intraprostatic Stent (ProstaCoil) in the Treatment of Prostatic Obstruction”, Br. J. Urol., 74 (1994), pp. 47–49.25. I Nissenkorn, S Richter and D Slutzker, “A Simple, Self-retaining Intraurethral Catheter for Treatment of Prostatic

Obstruction”, Eur. Urol., 18 (1990), pp. 286–289.26. A M Sassine and C C Schulman, “Intraurethral Catheter in High-risk Patients with Urinary Retention: 3 Years

of Experience”, ibid., 25 (1994), pp. 131–134.27. O Traxer, M Anidjar, F Gaudez, F Saporta, M Daudon, A Cortesse, F Desgrandchamps, O Cussenot, P Teillac

and A le Duc, “A New Prostatic Stent for the Treatment of Benign Prostatic Hyperplasia in High-risk Patients”,ibid., 38 (2000), pp. 272–278.

28. E Kemppainen, M Talja, M Riihela, T Pohjonen, P Tormala and O Alfthan, “A Bioresorbable Urethral Stent.An Experimental Study”, Urol. Res., 21 (1993), pp. 235–238.

29. T Isotalo, M Talja, T Valimaa, P Tormala and T L Tammela, “A Pilot Study of a Bioabsorbable Self-reinforcedPoly L-lactic Acid Urethral Stent Combined with Finasteride in the Treatment of Acute Urinary Retention fromBenign Prostatic Enlargement”, BJU Int., 85 (2000), pp. 83–86.

30. T Isotalo, M Talja, P Hellstrom, I Perttila, T Valimaa, P Tormala and T L Tammela, “A Double-blind,Randomized, Placebo-controlled Pilot Study to Investigate the Effects of Finasteride Combined with a BiodegradableSelf-reinforced Poly L-lactic Acid Spiral Stent in Patients with Urinary Retention Caused by Bladder OutletObstruction from Benign Prostatic Hyperplasia”, ibid., 88 (2001), pp. 30–34.

31. B Djavan, M Fakhari, S Shariat, K Ghawidel and M Marberger, “A Novel Intraurethral Prostatic Bridge Catheterfor Prevention of Temporary Prostatic Obstruction Following High Energy Transurethral Microwave Thermotherapyin Patients with Benign Prostatic Hyperplasia”, J. Urol., 161 (1999), pp. 144–151.

32. B Djavan, K Ghawidel, A Basharkhah, S Hruby, B Bursa and M Marberger, “Temporary Intraurethral ProstaticBridge-catheter Compared with Neoadjuvant and Adjuvant Alpha-blockade to Improve Early Results of High-energyTransurethral Microwave Thermotherapy”, Urology, 54 (1999), pp. 73–80.

33. M Talja, T Tammela, A Petas, T Valimaa, K Taari, E Viherkoski and P Tormala, “Biodegradable Self-reinforcedPolyglycolic Acid Spiral Stent in Prevention of Postoperative Urinary Retention After Visual Laser Ablation of theProstate-laser Prostatectomy”, J. Urol., 154 (1995), pp. 2,089–2,092.

34. A Petas, M Talja, T Tammela, K Taari, K Lehtoranta, T Valimaa and P Tormala, “A Randomized Study toCompare Biodegradable Self-reinforced Polyglycolic Acid Spiral Stents to Suprapubic and Indwelling Catheters AfterVisual Laser Ablation of the Prostate”, ibid., 157 (1997), pp. 173–176.

35. A Petas, M Talja, T L Tammela, K Taari, T Valimaa and P Tormala, “The Biodegradable Self-reinforced Poly-DL-lactic Acid Spiral Stent Compared with a Suprapubic Catheter in the Treatment of Post-operative UrinaryRetention After Visual Laser Ablation of the Prostate”, Br. J. Urol., 80 (1997), pp. 439–443.


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prostatic stents for the treatment of benign prostatic hyperplasia

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