Ureteral stents: the good the bad and the ugly

Ureteric stents are clinically deployed to restore urinary drainage in the presence of ureteric occlusions. They consist of a hollow tube with multiple side-holes that enhance urinary drainage. The stent surface is often subject to encrustation (induced by crystals-forming bacteria such as Proteus mirabilis) or particle accumulation, which may compromise stent's drainage performance. Limited research has, however, been conducted to evaluate the relationship between flow dynamics and accumulation of crystals in stents. Here, we employed a full-scale architecture of the urinary system to computationally investigate the flow performance of a ureteric stent and experimentally determine the level of particle accumulation over the stent surface. Particular attention was given to side-holes, as they play a pivotal role in enhancing urinary drainage. Results demonstrated that there exists an inverse correlation between wall shear stress (WSS) and crystal accumulation at side-holes. Specifically, side-holes with greater WSS levels were those characterized by inter-compartmental fluid exchange between the stent and ureter. These “active” side-holes were located either nearby ureteric obstructions or at regions characterized by a physiological constriction of the ureter. Results also revealed that the majority of side-holes (>60%) suffer from low WSS levels and are, thus, prone to crystals accumulation. Moreover, side-holes located toward the proximal region of the ureter presented lower WSS levels compared to more distal ones, thus suffering from greater particle accumulation. Overall, findings corroborate the role of WSS in modulating the localization and extent of particle accumulation in ureteric stents.

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“…This follows from previous studies that have investigated this process using colloidal suspensions as a urine surrogate. 29 …”

Section: Discussionmentioning

confidence: 99%

The accumulation of particles in ureteric stents is mediated by flow dynamics: Full-scale computational and experimental modeling of the occluded and unoccluded ureter

et al. 2022

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“…It can be deployed safely, is cost-effective and does not displace easily. 13,14 The associated pain and other side effects have been quantified to evaluate their impact on the patients' QoL ( Figure 1). There have been several attempts to improve patient tolerance to these ureteric stents (Table 1).…”

Section: Innovation Driven By Patients' Health-related Quality Of Lifmentioning

confidence: 99%

“…5 However, cystoscopy is often required to remove stents and is associated with potential complications and increased healthcare costs. 13…”

Section: Variations In Stent Removalmentioning

confidence: 99%

“…The idea is to insert another 9-Fr retrieval catheter which had a complementary magnet on its tip and the ureteral stent in situ could then be retrieved without direct visualisation. 13…”

Section: Stent Removal Issuesmentioning

confidence: 99%

“…Treatment is usually stent replacement, although alkaline medication such as sodium or potassium citrate can also reduce encrustations. 12,13…”

Section: Stent Blockagesmentioning

confidence: 99%

See 2 more Smart Citations

<p>Strategies to Improve Patient Outcomes and QOL: Current Complications of the Design and Placements of Ureteric Stents</p>

Ramachandra

Mosayyebi²,

Carugo³

et al. 2020

RRU

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Ureteric stents have played a vital role in relieving urinary obstruction in many urological conditions. Although they are extremely successful, stents have been associated with complications and reduced patients' health-related quality of life (HRQoL). There are many factors that may affect the quality and longevity of stents. In this review, we have highlighted the journey and innovation of ureteric stents through the modern day. A literature review was conducted to identify relevant articles over the last 20 years. There is a plethora of evidence with various indications for the use of ureteral stents and how they affect QoL. There is still ongoing research to develop the ideal stent with reduced encrustation, one that resists infection and is also comfortable for the patients. Stents made from metal alloys, polymers and biodegradable materials have unique properties in their own right but also have certain deficiencies. These have been discussed along with an overview of newly developed stents. Certain pharmacological adjuncts have also been highlighted that may be useful to improve patient's tolerance to stents. In summary, this paper describes the features of the different types of stents and the problems that are frequently encountered, including effect on patients' HRQoL and financial burden to healthcare providers.

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Simple bio‐inspired coating of ureteral stent for protein and bacterial fouling and calcium encrustation control

et al. 2023

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Encrustation, caused by deposition of calcium and magnesium salts present in urine, is a common problem of indwelling urinary devices, such as ureteral stent. Encrustation was also found to be related to urinary tract infections; thus, it is necessary to prepare ureteral stents with antibacterial and antifouling surfaces to mitigate the occurrence of encrustation. In this study, commercial ureteral stent was coated with polydopamine (PDA), formed from self‐polymerization of dopamine. The PDA coating was optimized in terms of dopamine concentration, pH, and coating time using response surface methodology. The chosen response parameters for optimization were calcium oxalate (CaC2O4) encrustation and protein adsorption. Optimized PDA coating conditions were determined to be the following: pH 9.0, 2 mg/mL DA, and 3 days coating. The optimized PDA‐coated ureteral stent exhibited outstanding resistance against CaC2O4 encrustation, protein fouling, and bacterial adhesion due to its hydrophilic and functional coating layer. In comparison with the pristine ureteral stent, PDA coating was able to suppress approximately 97% and 87% of CaC2O4 and protein adsorption, respectively. The PDA‐coated ureteral stent was compared against those of commercially available ureteral stents and found to have superior encrustation and protein fouling mitigation performance. Finally, PDA coating was found to be highly stable for a storage period of 90 days, whether stored in wet or dry conditions.

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Ureteral stents: the good the bad and the ugly

Cited by 13 publications

References 25 publications

The accumulation of particles in ureteric stents is mediated by flow dynamics: Full-scale computational and experimental modeling of the occluded and unoccluded ureter

The accumulation of particles in ureteric stents is mediated by flow dynamics: Full-scale computational and experimental modeling of the occluded and unoccluded ureter

<p>Strategies to Improve Patient Outcomes and QOL: Current Complications of the Design and Placements of Ureteric Stents</p>

Simple bio‐inspired coating of ureteral stent for protein and bacterial fouling and calcium encrustation control

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