Overview: role of stents in urology

Allium Stents: A Novel Solution for the Management of Upper and Lower Urinary Tract Strictures

Stents are widely use in endoscopic urological procedures. One of the most important indications is the treatment of urinary tract strictures. Allium™ Medical has introduced several types of stents for the treatment of different types of urinary tract strictures, based on anatomic location. All the stents are made of nitinol and coated with a co-polymer that reduces encrustations. These stents are self-expandable and have a large caliber and a high radial force. They have different shapes, designed especially for the treatment of each type of stricture. One of the most important features of Allium-manufactured stents is the ease of removal, due to their special unraveling feature. The company has introduced the Bulbar Urethral Stent (BUS) for treatment of bulbar urethral strictures; a rounded stent available in different lengths. Initial data on 64 patients with bulbar urethral stricture treated with the BUS showed a significant improvement in symptoms, with minimal complications and few adverse events. For treatment of prostate obstruction in patients unfit for surgery or unwilling to undergo a classical prostatic surgery, the Triangular Prostatic Stent (TPS) was introduced, which has a triangular shape that fits in the prostatic urethra. Its body has a high radial force attached to an anchor (which prevents migration) through a trans-sphincteric wire (which reduces incontinence rate). Initial data on 51 patients showed significant improvement in symptoms and in urinary peak flow rate, with a relatively small number of complications. The Round Posterior Stent (RPS) was designed for treatment of post radical prostatectomy bladder neck contracture. This short, round stent has an anchor, which is placed in the bladder neck. This stent being relatively new, the clinical data are still limited. Ureteral strictures can be treated with the Ureteral Stent (URS), which is round-shaped, available in different lengths, and has an anchor option (for very distal or very proximal strictures). We have previously published data on 107 URSs inserted in patients with ureteral stricture due to several etiologies, including patients who failed previous treatment. All patients were asymptomatic for a long period of follow-up after stent removal, with only one case of re-stenosis. In this paper, we review the urological "covered" stents produced by Allium Medical with the relevant clinical data available at the present time.

New device for intermittent emptying of the bladder in female children and adolescents: A pilot study

INTRODUCTION

Urinary incontinence (UI) is a challenging problem for the urological community. Clean intermittent catheterization (CIC) is the most commonly used method to restore bladder emptying to the state close to the physiological condition. This procedure can cause negative aspects such as pain and possible urethral injury. In addition, there is a negative impact on self-image and decline in quality of patient's life. The aim of the present study was to evaluate the safety and efficacy of a new intraurethral self-retaining device (ISRD), in female children and adolescents, as an attractive alternative to CIC.

MATERIALS AND METHODS

A prospective clinical pilot study was performed, in a single-institution, including female children and adolescent patients with urinary incontinence secondary to myelomeningocele who were already in an intermittent bladder catheterization program. Assessments included the use of a visual analogue scale in diagnosis of UI, reported adverse events, and the King's Health Questionnaire (KHQ) to evaluate quality of life, which was answered by patients and the caregivers of younger patients before and 6 months after enrolment.

DISCUSSION

The device was efficient and well tolerated by most patients (84%). The ISRD significantly improved quality of life in children and adolescents (p<0.0001 for both) (Table). The safe insertion and removal of the ISRD can be considered an advantage compared with CIC as eventual urethral trauma is significantly minimized. It was found that one of the main advantages of the ISRD is the possibility of management as an outpatient procedure both for initial insertion and replacement. The autonomy of patients to perform the bladder emptying process by themselves indicates the importance of this study, especially for school life and social interaction. ISRD use showed a tendency to improve the QoL.

CONCLUSIONS

This new bladder-draining device (ISRD) was effective and secure in terms of insertion technique, and improved QoL of patients with urinary retention and incontinence, according to domains evaluated in the KHQ.

Development of silver-containing austenite antibacterial stainless steels for biomedical applications part I: microstructure characteristics, mechanical properties and antibacterial mechanisms

The as-quenched (AQ) microstructure of the Ag-containing alloys was found to be essentially a mixture of austenite (γ) and Ag phases. The Ag phase precipitates had a face-centered-cubic structure and lattice parameter a = 4.09 Å. When the alloy contained Ag ≥0.2 wt%, the mechanical properties were slightly enhanced because of the precipitate strengthening by the Ag phase precipitates. Moreover, the Ag-containing alloys exhibited ductile fracture after tensile testing. The results of an antibacterial test revealed that the Ag phase precipitates play a key role in the antibacterial mechanism of Ag-containing alloys: Ag(+) ions released from the Ag phase precipitates can kill bacteria. It is suggested that as AISI 316L alloy has an Ag content ≥0.2 wt%, it will have excellent antibacterial properties against both Staphylococcus aureus and Escherichia coli, with an antibacterial rate of nearly 100%.

Reduction of bacterial adhesion on ion-implanted stainless steel surfaces

The high incidence of infections caused by the use of biomedical devices has a severe impact on human health. An approach to reduce the complications is to modify the surface properties of biomedical devices. In this paper, stainless steel disks were implanted with N(+), O(+) and SiF(3)(+), respectively, by an ion implantation technique. The surface properties of the ion-implanted surfaces were characterized, including their surface chemical composition, roughness, topography, wettability and surface energy. Bacterial adhesion of Staphylococcus epidermidis and Staphylococcus aureus, which frequently cause medical device-associated infections was evaluated. The experimental results showed that these implanted stainless steels, particularly SiF(3)(+) implanted stainless steel performed much better than untreated stainless steel control on reducing bacterial attachment.

Chapitre B-3 A - Traitement chirurgical des dysfonctions neurologiques des sphincters urinaires

The treatment of neurogenic detrusor-sphincter dyssynergia is primarily medical (drugs and catheterization). Some patients may not be eligible for or fail to respond to these treatment options and endoscopic sphincterotomy or permanent prosthesis may be indicated. In this article, the authors review the indications, results and contraindications of these various treatments.

Surface free energy effect on bacterial retention

Bacterial infection is one of the most frequent and severe complications in the long-term effectiveness of medical implants and devices, greatly increasing treatment cost and inconvenience to the patient. Surface physical and chemical properties are known to influence the extent and form of bacterial infection, although the exact correlation with specific properties is difficult due to the complexity of the system. One approach in the attempt to reduce the bacterial colonisation is to modify the surface energy and chemistry, so as to influence the interactions between the surface and the bacteria that come into contact with it. Five types of coatings were investigated in this study, together with silicone, and polished and non-polished stainless steel 316L. Surfaces were tested for retention of Pseudomonas aeruginosa AK1 after 1h. A good correlation (>90%) was found between P. aeruginosa AK1 retention and total surface free energy, as well as its polar and dispersive components. The minimum level of P. aeruginosa AK1 retention was found for a range of total surface free energy in the range 20-27 mN/m.

Ureteral stents and their use in endourology

Ureteral stents have assisted urologists in the performance of surgery of the urinary tract for many years. They can have both diagnostic and therapeutic value, but are used most frequently as adjuncts to endoscopic or minimally invasive procedures. This review provides an update of the current uses for ureteral stents, technology of biomaterials, complications associated with indwelling ureteral stents and the future of stents in urology.

A new temporary catheter (ContiCath) for the treatment of temporary, reversible, postoperative urinary retention

OBJECTIVES

To describe the initial experience of a newly designed temporary urethral catheter, ContiCath, as an aid in the management of postoperative or temporary outflow obstruction. In patients with normal detrusor and sphincter function, this catheter allows volitional voiding while maintaining an open prostatic urethra.

METHODS

In a pilot study, 64 nonconsecutive patients with postoperative or temporary urinary retention, at eight clinical trial sites, were enrolled for the placement of this temporary catheter. Three patients did not have the catheter placed because of placement failure because of either a large median lobe or a urethral stricture. The remaining 61 patients were divided into three groups: those with non-neuropathic causes of retention and retention for 1 week or less (37 patients), those with non-neuropathic causes of retention and retention for longer than 1 week (19 patients), and those with neuropathic causes of retention and retention for longer than 1 week (5 patients). The ContiCath is placed in the office setting, in the same fashion as a Foley catheter. A blue prolene tether extends from the bulbar urethra to the meatus to assist in the removal of the device. Patients were then reassessed at 3 hours, and at 7, 14, 21, and 28 days, at which point the device was removed.

RESULTS

In patients with a neuropathic cause for their retention (5 patients) and those with non-neuropathic causes of retention and retention for longer than 1 week (19 patients), only 3 patients were able to void after the catheter was placed. Of the 37 patients with a non-neuropathic cause and retention 1 week or less, controlled voiding was seen in 33 patients (89%). Controlled voiding was defined as the patient's volitional ability to initiate and stop his urinary stream. There were no complications with catheter placement; however, 8 patients (24.2%) had minor adverse experiences of frequency/urgency (n = 3), incontinence (n = 3), migration of the catheter (n = 1), and pain (n = 1).

CONCLUSIONS

ContiCath offers an alternative to an indwelling Foley catheter in men with temporary bladder outlet obstruction and urinary retention.