(UroToday.com) Awarded among one of the top ten abstracts at the AUA 2022, Rohit Bhatt and colleagues from the University of California, Irvine, gave an informative presentation on the biomaterial that best resists encrustation formation for ureteral stent design. Urological stents are an effective method of providing drainage of the upper urinary system.1 However, a common phenomenon with long indwelling stents is the buildup of urinary mineral deposits on stents, leading to encrustation. Stent encrustation is associated with increased morbidity, causing significant pain and discomfort to patients.2 Furthermore, forgotten encrusted stents can also result in undesirable financial burdens.3 In this study, five different stent materials were evaluated and compared in the rate of encrustation formation.
The research team presented their results on encrustation rates of five different stents after incubation in two different lithogenic artificial urine environments (AUE). Scanning electron micrograph (SEM) was used to assess each stent's surface and qualitatively evaluate the rate of encrustation. Inductively coupled plasma mass spectrometry (IC-PMS) was used to quantify the major ionic components of the encrusted crystals, such as magnesium, calcium, and phosphorus. The five tested stents are: 2-hydroxyethyl methacrylate (HEMA)-coated Pellethane, Boston Scientific Tria, Bard Inlay Optima, Cook Universa® Hydrogel, and Cook Black Silicone. Each stent was placed in a 37 °C AUE replicating condition of either 1) metabolic stone (calcium oxalate) formation or 2) infectious stones (struvite and calcium phosphate) formation. A controllable peristaltic pump system was used to exchange artificial urine solutions every 24-hours automatically. At weeks two and four, some stent materials were removed, air-dried, and analyzed via SEM to evaluate the extent of encrustation. At 11 weeks, all stent specimens were harvested and analyzed via ICP-MS. The analysis reviewed that HEMA-coated Pellethane stents had the most encrustation overall while the Cook Black Silicone had the least encrustation.
The figure above shows the SEM of the pristine stent surfaces, two-, and four-weeks of incubation in calcium phosphate/struvite and calcium oxalate-forming AUE. The blue arrows indicate pristine stent surfaces, while the red arrows illustrate the encrusted areas. High magnification of SEM (1500X) was used to show the features and texture of the pristine stents.
The table above shows the average mass change (mg) in all stents after 11-weeks of incubation in AUE. The table also shows the average mass (mg ± SD) of detected elements deposited on the surfaces of the stents after 11-weeks of incubation in the AUEs using the ICP-MS.
Rohit Bhatt and colleagues developed an in-depth protocol to evaluate the encrustation of ureteral stents. The study concluded that the Cook Black Silicone stent is the most optimal stent for patients who might require long-term indwelling stents. These results significantly affect patient care as patients with silicone stents can have lower chances of comorbidities due to encrustation.
Presented By: Rohit Bhatt B.S, 3rd-year medical student at St. Louis University School of Medicine and a LIFT (Leadership and Innovation Fellowship Training Program) Fellow at the University of California, Irvine @RohitBhatt_ on Twitter during the 2022 American Urological Association (AUA) Annual Meeting, May 13 - 16, 2022, New Orleans, Louisiana.
Coauthors: Yi X. Wu, Kalon L. Morgan, Eric J. Choi, Amberly A. Vu, Pengbo Jiang, Sohrab N. Ali, Roshan M. Patel, Jaime Landman, and Ralph V. Clayman
Written By: Paul Piedras, B.S., University of California, Irvine, during the 2022 American Urological Association (AUA) Annual Meeting, New Orleans, LA, Fri, May 13 – Mon, May 16, 2022.
References:- Leibovici D, Cooper A, Lindner A, et al. Ureteral stents: morbidity and impact on quality of life. Isr Med Assoc J. 2005;7(8):491-494.
- Lange, D., Bidnur, S., Hoag, N. & Chew, B. H. Ureteral stent-associated complications--where we are and where we are going. Nat Rev Urol 12, 17-25, doi:10.1038/nrurol.2014.340 (2015).
- Osman, N. I. & Collins, G. N. Urological litigation in the UK National Health Service (NHS): an analysis of 14 years of successful claims. BJU Int 108, 162-165, doi:10.1111/j.1464-410X.2011.10130.x (2011).