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

Figures & data

Figure 1 Effect of ureteric stent on patient symptoms and quality of life.

Table 1 Recent Innovations in Ureteral Stent Designs

Stent Issues	Innovative Design	Reference
Encrustation	Coating agent against biofilm formation	Szell et al^Citation61
Bacterial colonisation	Drug eluting stent	Lim et al^Citation62
“Forgotten stent”	Biodegradable stent	Barros et al^Citation37 Soria et al^Citation39
Migration	Telescoping stent Helical stent to control drainage Non-coplanar pigtails to avoid migration	Pendleton et al^Citation40 DeGraaf et al^Citation42 Yachia et al^Citation43
Urine reflux	Proximal end – anchoring structure and distal end – J tail into the renal pelvis Self-expandable mesh in the bladder and valve mechanism to prevent reflux	McMahon et al^Citation44 Shelton et al^Citation45

Table 2 Materials and Coatings Used for Novel Stents

Type of Material	Novel Material of Stents	Coating Used	Advantages/Key Points
Metal	Nickel Titanium (Nitinol)	Hyaluronic acid	Malleable – soft and durable Not indicated in patients with functional stenosis or stone formation
	Stainless steel	Silver	Easy to manufacture Retrieval can be difficult
	MP35N alloy (Nickel-cobalt-chromium – molybdenum)	Hyaluronic acid	Metallic pigtail stent with high tensile strength Resistant to corrosion
Polymeric	Silicone	Heparin	Highly biocompatible
	Polyurethane	Polyvinylpyrrolodine	High drainage performance and high epithelial erosion
	Silitek	Antibiotics	High tensile strength, weak coil retention, risk of oedema
	Percuflex	Chitosan Hydrogel Salicylic acid	Cost effective, efficient urine drainage and coil retention Low coil and tensile strength
	C-Flex	Carbon	Less surface friction, less particle adhesion, lower mechanical strength
	Dual durometer		Reduced bladder irritation
Biodegradable		Triclosan	Reduced secondary procedures

Table 3 Summary of Designs in Ureteral Stents

Type of Design	Key Features	Examples
Double-J	Commonly used design, reduced risk of migration
Double-J 3D	Provides better proximal and distal retention	Silicon Figure Four (SFF) (Bard^® USA)
Loop	Better patient comfort	Polaris™ Loop ureteral stent (Boston Scientific^®, USA)
Mesh	Reduced risk of bladder irritation but technically demanding	Uventa self expanding metallic mesh stent (Taewoong Medical, Seoul, Korea)
Expandable	High luminal flow, ease of insertion and retrieval	Allium^® Ureteral stent (Allium Medical Solutions^®, Israel)
Magnetic tip	Allows effective retrieval	Magnetic Black-Star (Urovision, Germany)
String	Facilitates stent removal by patient or surgeon in clinic	Boston Scientific^®, USA; Cook^® Medical, USA
Coil-reinforced	Allows efficient drainage, reduces kinking and buckling	Silhouette^® stent (Applied Medical USA)
Basket	Allows passage of small stones and prevents migration of bigger stones	Ureteral Stone Sweeper ^® (Fossa^® Medical, USA)
Spiral Cut	Potentially fewer upper tract symptoms	Boston Scientific^®, USA
Helical	Better drainage of urine and passage of small stones	Boston Scientific^®, USA
Grooved	Suitable for post lithotripsy to enable passage of stone fragments	Towers Peripheral Ureteral Stent (Cook^® Medical, USA)
Streamlined side-hole	Providing reduced particle deposition by increasing the wall shear stress at side-holes and enhancing fluid exchange between intra- and extra-luminal stent compartments.	No clinical data available currently

Figure 2 (A): Normal stent position. (B): Stent displaced, crossing the midline with encrusted bladder coil of the stent.

Szell TFFD, Goelz H, Bluemel B, et al. In Vitro Effects of a Novel Coating Agent on Bacterial Biofilm Development on Ureteral Stents. J Endourol. 2019;33(3):225–231. doi:10.1089/end.2018.061630458115

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Lim WS, Chen K, Chong TW, et al. A bilayer swellable drug-eluting ureteric stent: localized drug delivery to treat urothelial diseases. Biomaterials. 2018;165:25–38. doi:10.1016/j.biomaterials.2018.02.03529501967

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Barros AA, Oliveira C, Ribeiro AJ, et al. In vivo assessment of a novel biodegradable ureteral stent. World J Urol. 2018;36(2):277–283. doi:10.1007/s00345-017-2124-329128964

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Soria F, Morcillo E, Serrano A, et al. Evaluation of a New Design of Antireflux-biodegradable Ureteral Stent in Animal Model. Urology. 2018;115:59–64. doi:10.1016/j.urology.2018.02.00429470998

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Steven L, Pendleton GLN, Benjamin T. Biltz, inventor; Cook Medical Technologies LLC, assignee. Telescoping Ureteral Stent. 2018.

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Kimberly DeGraaf TPH, Mark W. BodenJan Seppala, inventor; Boston Scientific Scimed Inc, assignee. Controlled Extension Stent. 2017.

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Daniel Yachia VP, inventor; INNOVENTIONS Ltd, assignee. Stent and Method of Use; 2016.

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Charles Wesley McMahon CAN, Danielle Rae S, Lisa Jin C, Maria Guadalupe A, Sara L. Pelayo, inventor; Baylor University, assignee. Ureteral stent and method2017.

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Kurt G, Shelton AEP, inventor; Gyrus ACMI Inc, assignee. Ureteral stent with anti-migration features2015.

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