Ureteral stents: coil strength and durometer

Area of Science:

• Biomaterials Science
• Urology
• Medical Device Engineering

Background:

• Double-J ureteral stents are crucial for urinary tract drainage.
• Stent coil strength and stiffness are biomechanical properties influencing performance and patient comfort.
• Limited data exists on how urine exposure affects these properties.

Purpose of the Study:

• To quantify the coil strength of ureteral stents before and after urine exposure.
• To measure the stiffness (Young's modulus) of various ureteral stents.
• To correlate these biomechanical properties with stent performance and patient outcomes.

Main Methods:

• Twelve 6F ureteral stents underwent coil strength testing before and after 30 days of urine exposure.
• Coil strength was assessed by measuring recoil force after insertion into bologna.
• Tensile strength and stiffness (Young's modulus) were evaluated using a universal testing machine.

Main Results:

• Coil strength varied significantly among stent models and after urine exposure.
• Cook Black Silicone and Cook C-Flex showed highest initial coil strength but greatest post-exposure decrease.
• Cook C-Flex was the stiffest stent (E=1472 KPa), while Cook Black Silicone was least stiff (E=122 KPa).
• Stent stiffness consistency varied, with Circon Double J and Bard InLay showing reliable values across batches.

Conclusions:

• Ureteral stent coil strength and stiffness are key differentiating factors.
• These properties significantly impact stent performance and patient comfort.
• Variability in stiffness suggests potential quality control issues in manufacturing, complicating comparisons.