AUA 2022: A Prospective, Randomized, Single-Blind Study of Ureteral Stent Biomaterial Encrustation After Ureteroscopic Lithotripsy

( The 2022 AUA Annual meeting held in New Orleans held a session covering contemporary surgical therapies for stone disease featuring work from Dr. Shuzo Hamamoto and colleagues assessing degree and composition of encrustation and microbial biofilm formation on various ureteral stent materials. A mainstay for decompressing obstruction and preventing occlusion after urologic procedures (i.e., ureteroureterostomy, ureteral reimplantation, pyeloplasty, endoscopic procedures), ureteral stents play a crucial role in preserving renal function in short and long-term cases. Despite major advancements in the field of biomaterials, ureteral stent materials remain prone to encrustation induced by urine exposure and its contents (i.e., ions, microbial biofilm), resulting in accelerated degradation and need for replacement. As such, this abstract investigated the adherence of microbes and free ions on three commercially available stents, the Boston Scientific Percuflex (hydroplus coating), Boston Scientific Tria (percushield coating), Bard Inlay Optima (pHreecoat coating).


In this study, 61 patients undergoing endoscopic treatment for stones and required insertion of a stent were randomized to one of three stent groups. Stents were removed 1 month after placement and underwent follow-up analysis. Encrustation material was released from stents using a mixture of saline and hydrochloric acid, after which material underwent atomic absorption spectrometry to quantify calcium and magnesium deposits, and flow cytometry was utilized to assess bacterial composition.

In brief, the author’s study demonstrated that Group 1 (Percuflex) had the most significant amount of stone encrustation (33.3%, 11.7%, and 7.7%, respectively; p=0.02), median amount of Ca (5.51 (2.28-6.18), 1,91 (0.53-4.48), 2.30 (0.76-3.03) mg/dL respectively, p=0.024), median amount of Mg (0.20 (0.15-0.23), 0.06 (0.04-0.20), 0.03 (0.03-0.13) mg/dL respectively, p=0.005), and bacterial growth (33.76 (23.13-109.43), 13.80 (6.23-56.25), 8.33 (6.80-21.20), respectively, p=0.056) in comparison to Groups 2 and 3 .

There were no significant differences about patients and stone characteristics. The incidence of stone encrustation was significantly higher in Group 1 than in Groups 2 (Tria) and 3 (Inlay Optima) (33.3%, 11.7%, and 7.7%, respectively; p=0.02). The median amount (IQR) of Ca adhered to the stents in Group 1 was significantly higher than that in Groups 2 and 3 (5.51 (2.28-6.18), 1,91 (0.53-4.48), 2.30 (0.76-3.03) mg/dL respectively, p=0.024). The median amount (IQR) of Mg in Group 1 was significantly higher than that in Groups 2 and 3 (0.20 (0.15-0.23), 0.06 (0.04-0.20), 0.03 (0.03-0.13) mg/dL respectively, p=0.005). The median number (IQR) of bacteria was also highest in Group 1 (33.76 (23.13-109.43), 13.80 (6.23-56.25), 8.33 (6.80-21.20), respectively, p=0.056); however, there were no significant differences in bacterial adhesion.

Based off reduced deposition of Ca, Mg, and bacteria in Groups 2 and 3 stents, the author concluded that the Percushield coating associated with Boston Scientific Tria and the pHreeCoat coating associated with the Bard InLay Optima are superior to their Percuflex counterpart.



Presented by: Shuzo Hamamoto, Assistant Professor, Nagoya City University, Japan 

Written by: Rohit Bhatt, Leadership and Innovation Research Fellow, Department of Urology, University of California Irvine, @RohitBhatt_ on Twitter during the 2022 American Urological Association (AUA) Annual Meeting, New Orleans, LA, Fri, May 13 – Mon, May 16, 2022.

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