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      Reduction of ureteral stent encrustation by modulating the urine pH and inhibiting the crystal film with a new oral composition: a multicenter, placebo controlled, double blind, randomized clinical trial

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          Encrustation of ureteral double J stents is a common complication that may affect its removal. The aim of the proposed study is to evaluate the efficacy and safety of a new oral composition to prevent double J stent encrustation in indwelling times up to 8 weeks.


          A double-blinded, multicenter, placebo-controlled trial was conducted with 105 patients with indwelling double J stents enrolled across 9 public hospitals in Spain. The patients were randomly assigned (1:1) into intervention (53 patients) or placebo (52 patients) groups for 3 to 8 weeks and both groups self-monitored daily their morning urine pH levels. The primary outcome of analysis was the degree of stent ends encrustation, defined by a 4-point score (0 – none; 3 – global encrustation) using macroscopic and electron microscopy analysis of crystals, after 3 to 8-w indwelling period. Score was exponentially transformed according to calcium levels. Secondary endpoints included urine pH decrease, stent removal, and incidence of adverse events.


          The intervention group benefits from a lower global encrustation rate of stent ends than placebo group (1% vs 8.2%; p < 0.018). Mean encrustation score was 85.12 (274.5) in the placebo group and 18.91 (102.27) in the intervention group ( p < 0.025). Considering the secondary end points, treated patients reported greater urine pH decreases ( p = 0.002). No differences in the incidence of adverse events were identified between the groups.


          Our data suggest that the use of this new oral composition is beneficial in the context of ureteral double J indwelling by decreasing mean, as well as global encrustation.

          Trial registration

          This trial was registered at under the name “Combined Use of a Medical Device and a Dietary Complement in Patient Urinary pH Control in Patients With an Implanted Double J Stent” with date 2nd November 2017, code NCT03343275, and URL.

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          Most cited references 30

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          Bacterial biofilms in patients with indwelling urinary catheters.

           D. Stickler (2008)
          Bacteria have a basic survival strategy: to colonize surfaces and grow as biofilm communities embedded in a gel-like polysaccharide matrix. The catheterized urinary tract provides ideal conditions for the development of enormous biofilm populations. Many bacterial species colonize indwelling catheters as biofilms, inducing complications in patients' care. The most troublesome complications are the crystalline biofilms that can occlude the catheter lumen and trigger episodes of pyelonephritis and septicemia. The crystalline biofilms result from infection by urease-producing bacteria, particularly Proteus mirabilis. Urease raises the urinary pH and drives the formation of calcium phosphate and magnesium phosphate crystals in the biofilm. All types of catheter are vulnerable to encrustation by these biofilms, and clinical prevention strategies are clearly needed, as bacteria growing in the biofilm mode are resistant to antibiotics. Evidence indicates that treatment of symptomatic, catheter-associated urinary tract infection is more effective if biofilm-laden catheters are changed before antibiotic treatment is initiated. Infection with P. mirabilis exposes the many faults of currently available catheters, and plenty of scope exists for improvement in both their design and production; manufacturers should take up the challenge to improve patient outcomes.
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            Ureteral stent encrustation, incrustation, and coloring: morbidity related to indwelling times.

            Ureteral stents are a fundamental part of many urologic procedures. Serious complications, including migration, fragmentation, and stone formation, still occur, especially when stents have been forgotten for a long time. No widespread consensus for the type or indwelling time to avoid ureteral stent complications has been reached, however. We investigated the correlation between the indwelling time and encrustation, incrustation, coloration, and resistance to removal. A total of 330 ureteral stents in 181 patients were examined. Overall, 155 (47.0%) stents were encrusted, and the encrustation rate was 26.8% at less than 6 weeks, 56.9% at 6 to 12 weeks, and 75.9% at more than 12 weeks. A total of 46 (13.9%) stents resisted removal, and 3 of these could not be removed by cystoscopy. The median indwelling time was 72 (14-124) days for stents that resisted removal and 31 (30-60) days for irremovable stents. The frequency of encrustation with coloration was higher than that without coloration in the period of less than 6 weeks and the period between 6 to 12 weeks of indwelling time. In our study, although ureteral stent encrustation was related to the indwelling time, heavily encrusted ureteral stents necessitating additional procedures for removal occurred within an indwelling time of 3 months. The exact interval for removal of an indwelling ureteral stent to avoid additional procedures for removal is therefore difficult to determine.
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              Clinical complications of urinary catheters caused by crystalline biofilms: something needs to be done.

               D J Stickler (2014)
              This review is largely based on a previous paper published in the journal Spinal Cord. The care of many patients undergoing long-term bladder catheterization is complicated by encrustation and blockage of their Foley catheters. This problem stems from infection by urease-producing bacteria, particularly Proteus mirabilis. These organisms colonize the catheter forming an extensive biofilm; they also generate ammonia from urea, thus elevating the pH of urine. As the pH rises, crystals of calcium and magnesium phosphates precipitate in the urine and in the catheter biofilm. The continued development of this crystalline biofilm blocks the flow of urine through the catheter. Urine then either leaks along the outside of the catheter and the patient becomes incontinent or is retained causing painful distension of the bladder and reflux of urine to the kidneys. The process of crystal deposition can also initiate stone formation. Most patients suffering from recurrent catheter encrustation develop bladder stones. P. mirabilis establishes stable residence in these stones and is extremely difficult to eliminate from the catheterized urinary tract by antibiotic therapy. If blocked catheters are not identified and changed, serious symptomatic episodes of pyelonephritis, septicaemia and endotoxic shock can result. All types of Foley catheters including silver- or nitrofurazone-coated devices are vulnerable to this problem. In this review, the ways in which biofilm formation on Foley catheters is initiated by P. mirabilis will be described. The implications of understanding these mechanisms for the development of an encrustation-resistant catheter will be discussed. Finally, the way forward for the prevention and control of this problem will be considered.

                Author and article information

                BMC Urol
                BMC Urol
                BMC Urology
                BioMed Central (London )
                5 June 2020
                5 June 2020
                : 20
                [1 ]GRID grid.411129.e, ISNI 0000 0000 8836 0780, Bellvitge University Hospital, ; Barcelona, Spain
                [2 ]GRID grid.81821.32, ISNI 0000 0000 8970 9163, La Paz University Hospital, ; Madrid, Spain
                [3 ]GRID grid.411280.e, ISNI 0000 0001 1842 3755, Rio Hortega University Hospital, ; Valladolid, Spain
                [4 ]Mateu Orfila Hospital, Maó, Spain
                [5 ]GRID grid.418813.7, ISNI 0000 0004 1767 1951, Puigvert Foundation, ; Barcelona, Spain
                [6 ]GRID grid.459499.c, San Cecilio University Hospital, ; Granada, Spain
                [7 ]GRID grid.412800.f, ISNI 0000 0004 1768 1690, Virgen de Valme University Hospital, ; Sevilla, Spain
                [8 ]Álvaro Cunqueiro Hospital, Vigo, Spain
                [9 ]GRID grid.84393.35, ISNI 0000 0001 0360 9602, University and Polytechnic La Fe Hospital, ; Valencia, Spain
                [10 ]GRID grid.411048.8, ISNI 0000 0000 8816 6945, University Hospital Complex of Santiago de Compostela, ; Santiago de Compostela, Spain
                [11 ]GRID grid.9563.9, ISNI 0000 0001 1940 4767, Laboratory of Renal Lithiasis Research, , University Institute of Health Sciences Research (IUNICS- IDISBA), University of Balearic Islands (UIB), ; Palma de Mallorca, Spain
                [12 ]Devicare S.L., Cerdanyola del Vallès, Spain
                © The Author(s) 2020

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                ph, phytin, l-methionine, nutraceutical, encrustation, double j stent


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