Future Directions for Ureteral Stent Technology: From Bench to the Market

Abstract

Ureteral stents are broadly used for the treatment of a wide range of pathologies, with different complexities and characteristics. Despite being efficient, the morbidity associated with stents, such as bacterial infection and pain, limits their therapeutic action and often represents an increase in healthcare costs. As no single solution fits all problems, there is still a need to improve these medical devices. Throughout this review, the most recent innovations are outlined and suggestions regarding future directions for ureteral stent technology are formulated with respect to materials, coatings, and designs of these devices. As highlighted here, during the process of passing these innovations to the growing market of ureteral stents, one of the biggest challenges is to increase the predictive value of the in vitro assays and, consequently, reduce the number of in vivo tests needed. Thus, recommendations concerning in vitro standard testing of these devices are provided, with focus on medium, flow conditions, and microbiological parameters. Additionally, the reader is also presented with insights about a crucial but rarely discussed topic, the bureaucratic part of the bench to market process, particularly the product certification legislation in Europe.

Electromechanically Functionalized Ureteral Stents for Wireless Obstruction Monitoring

“…This consequently increases pressure inside the kidney, causing its swelling, a condition known as hydronephrosis that can lead to functional renal loss. In the interim, it can also lead to a widespread blood infection from the urine if bacteria flourish and multiply within the stagnant urine in the kidney, particularly in diabetics who have a lot of sugar in their urine. , Depending on the size and the location of the obstruction, the treatment may include placement of a ureteral stent into the ureter as a temporary support. ,, Ureteral stents are flexible hollow tubes, typically made of polymers, with a length of 20–30 cm and a diameter of less than 3 mm that are designed to be placed into an obstructed ureter to facilitate urine flow through it and help resolve the hydronephrosis. , …”

Fluid mechanical performance of ureteral stents: The role of side hole and lumen size

“…4,5 Although many efforts have been made to fight against biofilm and encrustation by means of material design and functional surface coatings, it remains one of the primary challenges in stent development. 2 Previous clinical observations have drawn attention to the side holes (SHs), which are small openings in the stent wall to facilitate exchange of fluids between the luminal (in the stent lumen) and extraluminal (between stent and ureter walls) spaces, that often end up heavily encrusted or completely occluded. [6][7][8] Once a SH becomes occluded, flow cavities in the vicinity also aggravate bacterial attachment, 9 further increasing the risk of infection.…”

“…Annually, there are over 1.5 million stents used worldwide; yet, more than 80% of the patients suffer from stent-related complications, posing significant threats to the quality-of-life of patients and creating economic burdens for the health care system. 2,3 Among all complications of indwelling stents, the frequent development of biofilm and encrustation remains a key limiting factor of stent efficacy. They are aggregates of conditioning films, bacterial colonies and crystals that start to accumulate on the stent surfaces once in contact with urine.…”

“…Modern ureteral stents also feature a curl at each end of the stent, known as pigtails, to prevent dislocation of the stent after placement. Annually, there are over 1.5 million stents used worldwide; yet, more than of the patients suffer from stent‐related complications, posing significant threats to the quality‐of‐life of patients and creating economic burdens for the health care system 2,3 …”

“…Depending on the actual physicochemical and microbiological environment, the composition may vary, but over time the growing volume will cause secondary stent obstructions that compromise the drainage capacity, and the bacterial content will significantly increase the chance of urinary tract infections 4,5 . Although many efforts have been made to fight against biofilm and encrustation by means of material design and functional surface coatings, it remains one of the primary challenges in stent development 2 . Previous clinical observations have drawn attention to the side holes (SHs), which are small openings in the stent wall to facilitate exchange of fluids between the luminal (in the stent lumen) and extraluminal (between stent and ureter walls) spaces, that often end up heavily encrusted or completely occluded 6–8 .…”