Encrustation and urinary tract infection are problematic complications of ureteral stent usage. The objective of our first study was to use surface science techniques to examine three ureteral stent types for encrustation, biofilm formation, and antibiotic adsorption after use in patients. Black Beauty (N = 16), LSe (N = 16), and SofFlex (N = 32) ureteral stents were recovered from patients who had received trimethoprim or ciprofloxacin while the stent was indwelling. These stents were examined with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX) for the presence and composition of encrustation or biofilm. Conditioning films and encrustations were found on all stents. Encrustation elements (Ca, Mg, P) were identified on 11 of 16 Black Beauty (69%), 7 of 16 LSe (44%), and 12 of 32 SofFlex (38%) stents. The stent type, duration of insertion, and age or sex of the patient did not correlate significantly with the amount of encrustation. Bacterial biofilms were found on 1 of 7 Black Beauty stents (14%) and 7 of 32 SofFlex stents (22%). In a second study, an additional 28 patients with SofFlex stents were treated with ciprofloxacin (N = 16) or ofloxacin (N = 12). Their stents were subjected to high-performance liquid chromatography to determine if oral antibiotic therapy can lead to drug adsorption to the stent. Analysis showed that both ciprofloxacin and ofloxacin adsorbed to the stent surfaces. The mean concentrations of the two antibiotics within the conditioning film of the stents were 0.99 microg/mL and 0.34 microg/mL, respectively. These surface science techniques provide a comprehensive method of evaluating ureteral stents and other prosthetic devices in vivo.
"UTI is one of these factors. Urease produced by bacteria hydrolyses urea in the urine to produce ammonia causing elevated urinary pH and favoring the precipitation of magnesium and calcium as struvite and hydroxyapatite onto the stent surface  . Duration of placement is another factor: various authors have reported that indwelling time between 2 and 4 months is safe     . "
[Show abstract][Hide abstract] ABSTRACT: Objectives
To present our experience in managing encrusted ureteral stents and to review the literature on the subject.MethodsA total of 22 patients with encrusted ureteral stent were treated in our department. Encrustation of the stent and associated stone burden were evaluated using plain radiography, sometimes supplemented by intravenous urography or ultrasonography. The treatment method was determined by the site of encrustation, the size of the stone burden and the availability of endourologic equipment.ResultsStents were inserted for stone disease in 17 patients, for congenital abnormality in 3 and for ureteric obstruction by malignancy in 2. Stents were left in place for a mean of 10.8 months (range 5–34 months). The site of encrustation was in the bladder in 15 (68.2%), ureter in 13 (59%) and kidney in 8 patients (36.4%); more than one site was involved in 11 (50%) cases. For upper coil encrustations, retrograde ureterorenoscopy was performed in 9 cases, percutaneous nephrolithotomy in 4 and open pyelolithotomy in 2. For lower coil encrustation, fragmentation by grasper and/or transurethral cystolithotripsy was attempted in 11 cases, and suprapubic cystolithotomy was required for failure in 7 cases. Sixteen patients (72.7%) were rendered stone-free and 5 (22.7%) had clinically insignificant residual stones (3 mm or less).Conclusions
Encrustation is one of the most difficult complications of ureteral stents and its management is a complex clinical scenario for the treating surgeon. The combination of several surgical techniques is often necessary but the best treatment remains the prevention of this problem by providing patient education.
African Journal of Urology 09/2012; 18(3):131–134. DOI:10.1016/j.afju.2012.08.013
[Show abstract][Hide abstract] ABSTRACT: Image-guided intervention for ureteral obstruction uses many of the same techniques and devices used in other nonvascular and vascular applications. In addition to direct percutaneous drainage of the collecting system through a nephrostomy tube, recanalization, balloon dilatation, and indwelling tube (double-J) stents are now standards of medical practice. However, double-J stents predispose a patient to infection, and are prone to occlusion from encrustation. As a possible long-term altermative, use of permanent metallic stents in the ureter is being investigated, but trials have so far shown mixed results. The physiology of urotheralial-lined, peristaltic ureteral tissue has proven to be remarkably different from that of the vascular and biliary systems, and acute tissue reaction and hypertrophy can be exuberant. Primary patency rates are relatively low, but in some cases of failed double-J stenting, metallic stents may play a useful role. Redirected research into permanent materials and designs customized for use in ureters is underway.
Techniques in Vascular and Interventional Radiology 03/1999; 2(1):53-58. DOI:10.1016/S1089-2516(99)80062-6
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