Management of recurrent urethral strictures with covered retrievable expandable nitinol stents: long-term results

Combining Transurethral Resection of Fibrous Tissue and Temporary Urethral Stent Insertion Is an Optimal Strategy for Minimally Invasive Treatment of Recurrent and Long Urethral Strictures

This study investigated the optimal strategy for the treatment of chronic recurrent urethral strictures longer than 3 cm, using a temporary urethral stent. Between September 2011 and June 2021, 36 patients with chronic bulbomembranous urethral strictures underwent temporary urethral stent placement. Retrievable self-expandable polymer-coated bulbar urethral stents (BUSs) were placed in 21 patients (group A), and thermo-expandable nickel-titanium alloy urethral stents were placed in 15 patients (group M). Each group was subdivided into those with and without transurethral resection (TUR) of fibrotic scar tissue. The urethral patency rates at 1 year after stent removal were compared between the groups. The patients in group A showed a higher urethral patency maintenance rate at 1 year after stent removal than those in group M (81.0% vs. 40.0%, log rank test p = 0.012). Analysis of subgroups in which TUR was performed due to severe fibrotic scar, showed that the patients in group A showed a significantly higher patency rate than patients in group M (90.9% vs. 44.4%, log rank test p = 0.028). In the treatment of chronic urethral strictures with a long fibrotic scar, temporary BUS combined with TUR of fibrotic tissue seems to be the optimal minimally invasive treatment strategy.

Bulbar Urethral Stents for Bulbar Urethral Strictures: Long-Term Follow-Up after Stent Removal

BACKGROUND/AIM

The aim of this study was to assess long-term clinical efficacy of temporary bulbar urethral stent (BUS) used for treatment of recurrent bulbar urethral stricture (US).

MATERIALS AND METHODS

A total of 168 patients with recurrent bulbar US who underwent BUS placement after internal urethrotomy between 2009 and 2019 were enrolled. An indwelling time of 12 months was planned for the stents. After stent removal, the criteria for success of BUS treatment were defined as follows: no evidence of stricture on urethrogram or endoscopy, more than 15 mL/s of urinary peak flow, and no recurrent urinary tract infections. Patients were divided into 2 groups based on clinical success and compared.

RESULTS

The mean age, US length, and indwelling time were 46.7 (±8.3) years, 2.32 (±0.4) cm, and 9.7 (±2.3) months, respectively. Median (range) follow-up was 71 (8-86) months. Clinical success was achieved in 77.9% patients. Longer indwelling time (8-18 [81.88%] vs. 3-7 [60%] months) and US length <2 cm (84.25% [<2 cm] vs. 58.5% [≥2 cm]) were significantly associated with clinical success (p < 0.05).

CONCLUSION

This study is both the largest patient series and the longest follow-up for BUS in bulbar US. Our results suggest that BUS can be a safe and minimally invasive treatment alternative among bulbar US treatment options.

Management of Recurrent Urethral Strictures: A Therapeutic Challenge

Urethral stricture disease is relatively common, and its management remains a therapeutic challenge for urologists despite recent advancements in endoscopic and reconstructive surgery. The majority of the strictures are acquired from injury or infection. Urethral stent implantation, a minimally invasive procedure, can be safely and effectively used as a primary surgical procedure in treating recurrent urethral stricture. Herein, we present a case of a 43-year-old male patient with complaints of intermittent urination, oliguria, and incomplete voiding with urinary frequency. Further urological investigations, a uroflowmetry, and a urethrogram were carried out. Oliguria, along with a mid-bulbar urethral stricture at the previous excision anastomotic site, was diagnosed. Despite a higher success rate of urethroplasty and temporary stent placement, urethral stricture recurrences are still an occurring entity. No definite therapeutic strategy has been adopted to evaluate and approach the morbidity effectively. Implementation of an effective primary procedure with minimally based complications should be generated to avoid future stricture recurrences. Larger-scale studies involving urethral stricture patients can gather sufficient data to obtain a complete curative treatment option for the future.

Design and Biomechanical Analysis of a Novel Retrievable Peripheral Vascular Stent

Structurally retrievable drug-eluting stents may have valuable clinical applications because they do not leave any foreign materials inside the patient's body. This article presents a novel design of retrievable peripheral vascular stent and the results from biomechanical analysis of its performance. Using the finite element analysis method, principal parameters of the stent were studied. Moreover, to ensure the practicability of the retrieval process, simulation, and in vitro experiments were performed. The retrieval force reached the maximum value when the whole retrievable part had been retrieved. Furthermore, the force was gradually increased during the retrieval process and remained constant after the main part had been retrieved. When the stent was being compressed, the maximum strain of the stent occurred at the connection between the stent's retrieval part and the main body part, at a value of 4%. The index of nonuniformity of the stent was too small to be counted both at the end of the compression and self-expansion processes. With the increase of moment, the bending stiffness (EI) of the stent decreased gradually. After bending moment was applied, the large strain region was mainly located in the stent's main body part rather than the retrieval part. The results of preliminary stent retrieval experiments demonstrated that the stent could be retrieved successfully. This novel retrievable stent displays promising biomechanical performance. The preliminary experiments demonstrated that the stent could be retrieved smoothly from the blood vessels.

Scarring Airway Stenosis in Chinese Adults: Characteristics and Interventional Bronchoscopy Treatment

Background:

Scarring airway stenosis is commonly seen in China as compared to other developed countries, due to the high prevalence of tuberculosis. Nowadays, interventional bronchoscopy treatment has been widely used to treat this disease in China. This study demonstrated the characteristics of scarring airway stenosis in Chinese adults and retrospectively evaluated the efficacy of interventional bronchoscopy treatment of this disease.

Methods:

Patients with scarring airway stenosis from 18 tertiary hospitals were enrolled between January 2013 and June 2016. The causes, site, and length of scarring airway stenosis were analyzed, and the efficacy of the interventional bronchoscopy treatment was evaluated.

Results:

The final study cohort consisted of 392 patients. Endotracheobronchial tuberculosis (EBTB) was the most common cause of scarring airway stenosis (305/392, 77.8%) in Chinese adults with a high rate of incidence in young women. The left main bronchus was most susceptible to EBTB, and most posttuberculosis airway scarring stenosis length was 1.1–2.0 cm. The average clinical success rate of interventional bronchoscopy treatment for scarring airway stenosis in Chinese patients is 60.5%. The stent was inserted in 8.7% scarring airway stenosis in China.

Conclusions:

Scarring airway stenosis exhibits specific characteristics in Chinese patients. Interventional bronchoscopy is a useful and safe treatment method for the disease.

Implantação de stent autoexpansível para tratamento de estenose uretral em cão: relato de caso

RESUMO O stent endovascular autoexpansível pode ser utilizado como forma de tratamento para estenose uretral em cães. O stent de nitinol é composto por uma liga de níquel e titânio que permite mudanças em suas estruturas sob a influência da temperatura corporal e tem excelente biocompatibilidade na uretra canina. Este estudo relata o caso de um cão, sem raça definida, 14 anos de idade, com histórico de disúria há duas semanas, diagnosticado com grande quantidade de cálculos e microcálculos na bexiga, no colo vesical e na uretra prostática, também cistite e hiperplasia prostática. Depois de tratamento para cistite, orquiectomia e cistotomia para retirada dos cálculos, porém sem melhora clínica após 30 dias de acompanhamento, com o paciente apresentando disúria, foi realizada uretrocistografia retrógrada, que evidenciou estenose da uretra prostática. Esse paciente foi encaminhado para procedimento de implantação de um stent de nitinol na uretra prostática. Imediatamente após o procedimento e até o presente momento, o paciente apresenta micção espontânea, sem qualquer sinal de disúria, sendo este o primeiro relato no Brasil do uso dessa técnica.

EW-7197 eluting nano-fiber covered self-expandable metallic stent to prevent granulation tissue formation in a canine urethral model

PURPOSE

To evaluate an EW-7197-eluting nanofiber-covered stent (NFCS) for suppressing granulation tissue formation after stent placement in a canine urethral model.

MATERIALS AND METHODS

All experiments were approved by the committee of animal research. A total of 12 NFCSs were placed in the proximal and distal urethras of six dogs. Dogs were divided into two groups with 3 dogs each. The control stent (CS) group received NFCSs and the drug stent (DS) group received EW-7197 (1000 μg)-eluting NFCSs. All dogs were sacrificed 8 weeks after stent placement Histologic findings of the stented urethra were compared using the Mann-Whitney U test.

RESULTS

Stent placement was technically successful in all dogs without procedure-related complications. On urethrographic analysis, the mean luminal diameter was significantly larger in the DS group than in the CS group at 4 and 8 weeks after stent placement (all p < 0.001). On histological examination, mean thicknesses of the papillary projection, thickness of submucosal fibrosis, number of epithelial layers, and degree of collagen deposition were significantly lower in the DS group than in the CS group (all p < 0.001), whereas the mean degree of inflammatory cell infiltration was not significantly different (p > 0.05).

CONCLUSION

The EW-7197-eluting NFCS is effective and safe for suppressing granulation tissue formation after stent placement in a canine urethral model.

The long-term results of temporary urethral stent placement for the treatment of recurrent bulbar urethral stricture disease?

Aim:

To evaluate the long term outcomes of temporary urethral stent placement for the treatment of recurrent bulbar urethral stricture.

Materials and Methods:

Twenty-eight patients who underwent temporary polymer coated urethral stent placement due to recurrent bulbar urethral stricture between 2010 and 2014 were enrolled in the study. The long term outcomes of the patients were analyzed.

Results:

The mean age of the patients was 62.3±6.4 (44–81). The overall clinical success was achieved in 18 (64.2%) of the 28 patients at a median (range) follow-up of 29 (7–46) months. No patient reported discomfort at the stent site. Stone formation was observed at the urethral stent implantation area only in one patient. Stenosis occurred in the distal end of the stents in two patients and took place in bulbar urethra in seven patients after removed the stents. The mean maximum urine flow rates were 6.24±2.81mL/sec and 19.12±4.31mL/sec before and at 3 months after the procedure, respectively.

Conclusion:

In this study, the success rate of temporary urethral stent placement has remained at 64.2% at a median follow-up of 29 months. Therefore, our outcomes have not achieved desired success rate for the standard treatment of recurrent bulbar urethral stricture.

Polydioxanone biodegradable stent placement in a canine urethral model: analysis of inflammatory reaction and biodegradation

PURPOSE

To investigate the inflammatory reaction and perform quantitative analysis of biodegradation after placement of a polydioxanone (PDO) biodegradable stent in a canine urethral model.

MATERIALS AND METHODS

PDO biodegradable stents were placed in the proximal and distal urethra of nine male mongrel dogs. The dogs were euthanized 4 weeks (group A; n = 3), 8 weeks (group B; n = 3), or 12 weeks (group C; n = 3) after stent placement. The luminal diameter of the stent-implanted urethra was assessed by follow-up retrograde urethrography, and histologic findings were obtained after the dogs were killed. Stents were removed after euthanasia, and their surface morphology and molecular weight were evaluated. Hematologic examination was performed to evaluate inflammatory reaction.

RESULTS

Stent placement was technically successful in all dogs. The average luminal diameter gradually decreased. The average number of epithelial layers (2.93 vs 4.42; P < .001), the average thickness of papillary projection (0.80 mm vs 1.28 mm; P < .001), and the average thickness of submucosal fibrosis (0.34 mm vs 0.49 mm ; P < .001) were significantly increased in group B versus group A. There were no significant differences between group B and group C. The average inflammatory cell infiltration did not differ significantly in the three groups. Molecular weight losses were 54% in group A and 84% in group B. In group C, PDO stents were completely decomposed.

CONCLUSIONS

An experimental study in a canine urethral model has demonstrated acceptable inflammatory reaction with gradually increasing granulation tissue but no luminal obstruction within 12 weeks.

Male urethral strictures and their management

Male urethral stricture disease is prevalent and has a substantial impact on quality of life and health-care costs. Management of urethral strictures is complex and depends on the characteristics of the stricture. Data show that there is no difference between urethral dilation and internal urethrotomy in terms of long-term outcomes; success rates range widely from 8-80%, with long-term success rates of 20-30%. For both of these procedures, the risk of recurrence is greater for men with longer strictures, penile urethral strictures, multiple strictures, presence of infection, or history of prior procedures. Analysis has shown that repeated use of urethrotomy is not clinically effective or cost-effective in these patients. Long-term success rates are higher for surgical reconstruction with urethroplasty, with most studies showing success rates of 85-90%. Many techniques have been utilized for urethroplasty, depending on the location, length, and character of the stricture. Successful management of urethral strictures requires detailed knowledge of anatomy, pathophysiology, proper patient selection, and reconstructive techniques.

Durability of Memokath™ urethral stent for stabilisation of recurrent bulbar urethral strictures -- medium-term results

OBJECTIVE

To examine the durability after 3 months deployment of a urethral (Memokath™) stent in conjunction with endoscopic treatment of recurrent bulbar urethral strictures, as repeated endoscopic treatment of urethral strictures can cause worsening of underlying spongiofibrosis.

PATIENTS AND METHODS

Prospective series of 22 patients with recurrent bulbar strictures requiring repeat endoscopic treatment were included. The median age was 38 years and the mean stricture length was 2.4 cm. The median number of previous dilatation or direct visual internal urethrotomy (DVIU) procedures was three with a mean time to stricture recurrence of 2 months. After endoscopic dilatation or DVIU, the urethral (Memokath™) stent was deployed and left situ for 3 months. Re-stricture rates were examined with uroflowmetry at 3, 6 and 12 months and confirmed with 17-F cystoscopy at 1 year after stent removal. A telephone survey was conducted at >1-year follow-up.

RESULTS

Five of the 22 (22%) patients had stricture recurrence after stent removal. In all, 17/22 (78%) patients remained stricture-free at a median (range) follow-up of 23 (9-31) months. Uroflowmetry showed significantly improved flow rates, which were sustained at 12 months after stent removal. On Kaplan-Meier analysis, there was a significant delay (23 vs 2 months) in stricture or symptom recurrence after stent removal.

CONCLUSION

The medium term results of temporary urethral stent placement are encouraging with 78% of patients remaining stricture-free at a median follow-up of 23 months.

Treatment of traumatic penile urethral stricture in a dog with a self-expanding, covered nitinol stent

CASE DESCRIPTION

An 8-month-old castrated male mixed-breed dog was evaluated because of hematuria, stranguria, and dysuria of approximately 2 weeks' duration that developed immediately following elective castration.

CLINICAL FINDINGS

Results of physical examination, ultrasonography, retrograde double-contrast cystourethrography, and urethroscopy were consistent with a traumatic urethral stricture immediately proximal to the os penis resulting in a partial obstruction of urine outflow. Results of ultrasonographic examination of abdominal organs were considered normal. Digital radiography revealed no evidence of calculi.

TREATMENT AND OUTCOME

Balloon dilation of the urethral stricture was performed and was followed by 2 bougienage procedures during the subsequent 2 weeks when clinical signs returned. The owners declined scrotal urethrostomy, and a self-expanding, covered nitinol stent was placed approximately 3 weeks after the initial evaluation, resulting in amelioration of clinical signs. Results of follow-up urethroscopy and contrast cystourethrography 1 year after stent placement revealed a statically positioned, patent urethral stent, although a small number of polypoid mucosal structures were identified distal to the stent and 1 small structure consistent with tissue ingrowth into the stent was identified.

CLINICAL RELEVANCE

Placement of a covered nitinol stent resulted in long-term resolution of clinical signs associated with traumatic stricture of the penile urethra in this young dog. Because the os penis in dogs limits radial expansion of the urethra, its presence may limit the use of stents in this location.

Retrospective comparison of internally and externally covered retrievable stent placement for patients with benign urethral strictures caused by traumatic injury

OBJECTIVE

The purpose of this article is to compare the clinical effectiveness and complications of externally and internally covered stents for the treatment of benign urethral strictures.

MATERIALS AND METHODS

From July 2002 to June 2010, 59 retrievable self-expandable polytetrafluoroethylene-covered nitinol stents were placed in 33 men with benign urethral strictures. These included 34 internally covered stents placed in 18 patients (group I) and 25 externally covered stents in 15 patients (group E). Stents were routinely removed 4 months after placement from patients who experienced no complications. Complications, duration of stent placement, removal techniques, and maintained patency rates were compared in the two groups.

RESULTS

Twenty-eight complications (82.4%) occurred in 15 patients in group I, whereas 12 complications (48%) occurred in six patients in group E (p=0.005). Three (16.7%) patients in group I and nine (60%) in group E had their stents electively removed without complications (p=0.010). Stent migration was more frequent in group I (47.1%) than in group E (24.0%). No tissue ingrowth was detected in group E, whereas six cases of tissue ingrowth occurred in group I (p=0.034). The standard technique was used more frequently in group E (70.8%). The median stent indwelling period was significantly shorter in group I than in group E (51.5 vs 114 days; p=0.34).

CONCLUSION

Despite their relatively high complication rates, externally covered stents are more effective with fewer complications than internally covered stents in the treatment of benign urethral strictures.

Critical appraisal of the Spanner™ prostatic stent in the treatment of prostatic obstruction

The Spanner™ stent was first used in patients to relieve bladder outlet obstruction (BOO), and has recently been used in patients following transurethral microwave thermotherapy and men unfit for surgical intervention. We review the current literature on the role of the Spanner stent in treating prostatic obstruction compared to previously reported cases involving the use of temporary stents. The Spanner stent has been found to be successful in treating patients with bladder outlet obstruction from benign prostatic hyperplasia and following high-energy transurethral microwave thermotherapy (TUMT). Patients with the Spanner stent had an increase in peak flow rate and a decrease in post void residual and International Prostate Symptom Scores. In patients treated with TUMT, quality of life measures indicate that the Spanner stent shows increased ease of bladder drainage, decreased leakage, and no adverse effect on daily activities. In patients unfit for surgery, however, there was increased retention and pain requiring stent removal in 63% of cases. The Spanner stent offers ease of insertion with a decrease in voiding symptoms in selected patients. Based on limited data, the Spanner stent has been recommended as a treatment option for men with BOO following TUMT. However, it is not a good treatment option for men unfit for surgery based on an increased incidence of urinary retention and dysuria. The Spanner stent is the only currently approved temporary stent and, based on a literature review, it does not offer significant advantage over previously used temporary stents. It is notable that most researchers have not evaluated the role of detrusor function on the outcomes.

New biodegradable drug-eluting stents for urethral strictures in a rabbit model

In this study, the feasibility and the effect of a new biodegradable drug-eluting urethral stents for the treatment of urethral stricture in a rabbit model were evaluated, and the biocompatibility properties of the new biodegradable drug-eluting urethral stents in the rabbit urethral assessed. A total of 34 male New Zealand White rabbits with urethral strictures were used, and equally divided into two groups: with drug stents and drug-free stents. The urethral strictures were made by using a self-control explosion device as the control. Stents were surgically implanted into the stenotic urethras of rabbits under direct vision. Reparative effects, including biocompatibility assessment, were evaluated by urethroscopy, retrograde urethrography, and histology at different intervals at weeks 4, 8, and 12. Although retrograde urethrography and urodynamic results at 12 weeks showed no comparable differences among the three groups, urethroscopic and histological follow-up indicated that the drug stents had minimized the stent-related inflammatory responses, urothelial hyperplasia, and scar formation compared with the drug-free stents. The new biodegradable paclitaxel-eluting stents were more biocompatible and effective for treating urethral strictures in the rabbit model than the drug-free stents.