27. Surgical Urethral Reconstruction After Failed Urethral Stents

Javier C. Angulo¹, Reynaldo Gomez², Dmitriy Nikolavsky³ and Francisco E. Martins⁴

(1)

Clinical Department, Faculty of Biomedical Sciences, Hospital Universitario de Getafe, Universidad Europea de Madrid, Madrid, Spain

(2)

Universidad Andres Bello, Hospital del Trabajador, Santiago, Chile

(3)

Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA

(4)

Department of Urology, University of Lisbon, School of Medicine, CHLN/Hospital Santa Maria, Lisbon, Portugal

Javier C. Angulo (Corresponding author)

Reynaldo Gomez

Email: rgomez@hts.cl

Dmitriy Nikolavsky

Email: Nikolavd@upstate.edu

Francisco E. Martins

Keywords

Urethral stentUrethroplastyUroLumeMemokathSurgical techniqueResults

27.1 Use of Stents for Urethral Stricture

Urethral strictures are typically caused by inflammation or trauma. Endoscopic treatments of a urethral stricture is a controversial issue as the success of different endoluminal therapeutical options depends on numerous factors related to the procedure type, the stricture etiology, length and location, the degree of spongiofibrosis and the magnitude of the inelastic scar within stricture. Visual urethrotomy evolving full-thickness incisions through the depth of the scar or urethral dilatation also result in further scarring after damage of epithelium, spongiosal tissue and surrounding muscle fibers.

Urethral stents were introduced in the 1980s with the intention to prevent scar contraction after dilatation or urethrotomy. Both permanent and temporary stents were introduced, both being subject to either staged removal or periodic change. Initially the stents were designed to be placed after dilatation as an alternative to internal urethrotomy for recurrent bulbar strictures. Unfortunately their widespread use has led to very disappointing results, not only due to complications, but also due to the daunting task of dealing with removal of the embedded prosthesis and difficult late urethral reconstruction [1].

27.1.1 History of Permanent Stents

The self-expanding Wallstent was developed for vascular disease by Hans Wallstent, taking into account a wire banding braided technology also used to the manufacturing of coaxial cables. In Urology it mainly served to maintain the patency of a stenosed bulbar urethra after dilatation as initially described by Milroy in 1988 [2]. Treatment of urethral stricture using UroLume (American Medical Systems, Minnetonka, Minesota) urethral stent was approved by the Food and Drug Administration since 1988 and since then distributed in many countries until being discontinued in 2011. This endoprosthesis manufactured in Switzerland was biocompatible, flexible and self-expanding, and rapidly evolved to be considered a good alternative to dilatation and internal urethrotomy to treat recurrent bulbar strictures [3]. At that time urethroplasty was too often performed only after repeat failure of endoscopic methods because urologists erroneously believed in a “reconstructive surgical ladder ” and only considered urethroplasty after repeat failure of endoscopic methods [4, 5].

Soon after the UroLume was developed, another meshed knitted stent, the thermo-expandible Memotherm (Bard, Murray Hill, New Jersey) became available. It’s use was indicated for urethral strictures less than 3 cm long with at least a 10-mm interval of healthy urethra present distal to the external sphincter. The stent was intended to be at least 10 mm longer than the stricture, as 5 mm were estimated to be added to each end of the stricture [6]. The main proposed advantage of both types of permanent stents was that urothelium growing through the interstices and covering the wires would theoretically prevent it from migration and would prevent it being exposed to urine and thus prevent encrustation or infection. This turned out to be their main disadvantage as urethral stricture would progress through a process of spongiofibrosis and hyperplastic overgrowth resulting in restenosis adjacent to and inside the prosthesis (Fig. 27.1). The patients with the progression of the disease would present with numerous persistent problems including perineal pain, urinary retention and urinary infections.

../images/468369_1_En_27_Chapter/468369_1_En_27_Fig1_HTML.png — Fig. 27.1

2.5 cm UroLume stent on bulbo-membranous urethra with hyperplastic overgrowth causing restenosis inside the prosthesis

Hyperplastic tissue ingrowth and intra-stent tissue frequently occurred in post-traumatic strictures [7]. For that reason permanent stents were considered contraindicated in strictures after trauma. Additionally, because of their wide caliber and cylindrical shape, permanent stents could only be useful in the bulbar urethra. In the other parts of the urethra their use was contraindicated because due to the sharp ends causing pain and further urethral injury. In addition, urethral stents placed within the previous urethroplasty beds could not become entirely incorporated and epithelialized and were thus prone to stone formation and recurrent infections. For all these reasons the results were often disappointing and at a longer follow-up demonstrated high rates of restenosis. Regretfully, only 13% of the implanted patients had subjectively satisfactory results at 10 years [8]. A re-intervention due to stent-related complications occurred in one out of every three patients in the long term [1, 9]. As a result, the experts in urethral reconstruction have not been using them in any situations including for the “ideal” candidates with bulbar urethral strictures. It is a consensus that stents should never have been used for penile urethral strictures, long strictures or urethral scarring after pelvic floor urethral distraction defects. However, due to their ease of use, the stents were frequently misused, and even placed in tandem for longer strictures (Fig. 27.2).

../images/468369_1_En_27_Chapter/468369_1_En_27_Fig2_HTML.png — Fig. 27.2

Two 2.0 cm UroLume stents placed on pendulous and bulbar urethra with re-stricture adjacent to both proximal and distal ends of the tandem stented segment

We really do not know how many permanent stents have been explanted in the long term and there is no knowledge of how many patients are still bearing these type of endoprosthesis. Still though, despite it is now more than 15 years that stents they are not available the patients return with re-strictures and pose a very interesting challenge to the reconstructive centers worldwide [10].

27.1.2 Temporary Stents

Results with the temporary stents were not as disappointing as those with the permanent stents, which would explain why they are still in use today being used occasionally for treatment of recurrent urethral strictures, post-prostate cancer treatments, urethrovesical anastomotic stenosis, recurrent ureteral stenosis and uretero-ileal anastomotic stenosis as well.

Memokath (Pnn Medical, Denmark) is a biocompatible endoprosthesis made of nickel and titanium alloy (nitinol) that anchors by expansion of its proximal end in responce to a warm water instillation after being inserted through a lumen opened by direct vision internal urethrotomy or progressive dilatation. In contrast to permanent stents, it is not embedded into the mucosa. This quality in combination with its thermal shape-memory allow for an easy transurethral removal. However, due to the stent’s constant exposure to urine, the initial reports also described luminal narrowing due to encrustation in 1 out of 4 patients and recurrent stricture in 1 of 5 [11]. Complications were shown to increase with time as epithelial hyperplasia tends to develop at around 1 year follow-up [12], which makes this device useful only for temporary stenting.

A multicenter randomized controlled trial demonstrated that patients with recurrent bulbar urethral stricture treated with Memokath stent after dilatation or internal urethrotomy have maintained their urethral patency longer than those treated with dilatation or DVIU alone [11]. However, another feasibility study where Memokath stent was used for treatment of recurrent bulbar strictures, has concluded that this treatment has significant side-effects and is not clinically useful [13]. Also urethroplasty in these cases is totally feasible and is very effective to achieve and maintaining urethral patency after non-desired Memokath urethral re-stenting [14].

Allium stent (Allium Medical, Caesarea Industrial Park, Israel) has a nitinol skelton covered with a biocompatible polymer that is resistant to urine environment, thus acting as an impermeable walled tube that prevents tissue ingrowth into the lumen. It can be removed easily, even 1 year after implantation, by pulling its downstream end with an endoscopic forceps causing the stent to unravel and to be taken out as a tape. Clinical experience with Allium is scant, but at least this device does not seem to suffer migration or problems at the time of endoscopic extraction [15, 16].

27.2 The Problems of Urethral Stenting

Urethral stent placement was enthusiastically incorporated in the 1990s as a minimally invasive therapy for recurrent bulbar strictures with promising early results in the absence of extensive periurethral fibrosis [2, 17–19]. However, long-term results showed progressive deterioration of the initial attractive results due to hyperplastic overgrowth with secondary restenosis, stent migration, encrustation, urinary infection and other side effects that impacted patients’ quality of life and included pain with erections and complaints of postvoid dribbling [1, 5, 20]. This knowledge of the delayed complications has replaced the initial good acceptance of this technology with extreme precaution. The disappointment came not only from the high rate of stricture disease recurrence, but also from the degree and complexity of complications requiring operative interventions (urethral dilatation or urethrotomy for stricture, transurethral resection for hyperplasia and litholapaxy for encrustation) and occasionally quite elaborate definitive stent removal [1, 7] (Fig. 27.3).

../images/468369_1_En_27_Chapter/468369_1_En_27_Fig3_HTML.png — Fig. 27.3

3.0 cm UroLume stent with severe distal urethra restenosis in a patient performing long-term auto-dilatation before definitive stent removal and urethral reconstruction

While endoscopic removal of a prostatic urethral stent can be feasible and safe with use of a holmium laser [21], open stent explantation with urethral reconstruction for a failed urethral stent is frequently necessary and is always challenging [5, 22]. Severe polypoid hyperplasia and inflammatory infiltrate, the histological changes associated with long-term urethral stents, discourage endoscopic removal in most cases [23]. Endoscopic stent removal wire by wire is possible after transurethral stent cutting [9]. However, an open en-bloc removal of the scarred urethra together with the entrapped stent has been the preferred choice in cases requiring a more definite reconstruction [5].

The thermo-expandable Memokath stent was designed for easy implantation and removal from urethra. However, being often left in place for 6–12mo before removal, it is not devoid of encrustation and recurrent stricture. This treatment should be considered as a temporary option, and should not be used in patients who are fit for urethroplasty [13, 24, 25]. Additionally, a recent report has shown good results after urethroplasty in patients with previous Memokath stent, and could contribute to a further argument discouraging temporary stenting in patients willing to undergo a definite reconstruction [14].

27.3 Management of Re-Stricture after Urethral Stent Use

Management of re-stricture after urethral stent placement is becoming an infrequent situation now that urethral stents are very rarely used as primary treatment for complex urethral stricture. However, technically speaking, various valid alternatives exist for performing urethroplasty with simultaneous stent removal [22]. Several methods of one-stage repair have been described as successful, and involve either a complete full-segment urethral excision or urethral preservation with tine-by-tine stent extraction following longitudinal urethrotomy [26–28] (Fig. 27.4). However, a two-stage surgery can be sometimes a more judicious decision, always to be undertaken in an individual basis, depending on the degree of fibrosis surrounding the stent, the length of the stricture and its concrete topography. There are different options that can be used for a two-stage repair, including techniques involving the use of buccal mucosa patch to augment temporary urethrostomy. In some occasions, diffuse periurethral abscess with total lack of urethral patency may preclude immediate reconstruction, in which case a definite perineal urethrostomy can be the only choice. The decision on how to perform a stent retrieval and urethral reconstruction can be difficult and management needs being decided on an individual basis.