(UroToday.com) Dr. Shuzo Hamamoto and his team from Nagoya, Japan spoke on ureteral stents and its adverse effect of encrustation. Ureteral stents are routinely used by all urologists following ureteroscopies as a safety measure ensuring patients can void urine successfully. Stents can be made of different materials to identify and optimize mechanical strength, flexibility, biocompatibility, surface roughness, and cost effectiveness.1 Encrustation is one major drawback when stents are left implanted in a patient for an extended period. Dr. Hamamoto and his team looked to test different stent compositions and their ability to encrust in hopes of finding the optimal stent material that is least likely to stent.
Dr. Hamamoto et. al. recruited 61 patients who underwent treatment of urinary calculi followed by the placing of a stent. Group 1 patients had a Percuflex stent made of a Hydroplus, group two stent was made by Tria and contained a Percushied coating, and finally, group 3 stents were composed of InLay Optima that had a proprietary pHreecoat coating. Stents were left in place for one month post treatment (Figure 1). Once removed, stents were treated with a solution of saline and hydrochloric acid followed by being vortexed for an hour. Calcium (Ca) and magnesium (Mg) ions were measured via spectrometry, while the bacteria were measured using flow cytometry.
Dr. Hamamoto and his team found no significant differences between patients and stone characteristics. Group 1 stents had a significantly higher encrustation than group 2 and 3 stents. In addition, more Ca and Mg ions adhered to stents in group 1 than the stents in groups 2 and 3. Interestingly, bacteria were found to be highest in group 1 stents but there were no significant differences in bacterial adhesion between stent material (Figure 2). The team was able to conclude that stents with Percushield and pHreeCoat coatings decreased adherence to Ca and Mg ions following endoscopic treatment. Following his presentation, one of the moderators asked about Dr. Hamamoto's experience with another stent material, silicone; to which Dr. Hamamoto stated that “In the future, I would like to further investigate silicone stents”. The moderator continued to ask a question by asking why the patients had a stent in place for 30 days as it is usually required to remove as soon as quickly. Dr. Hamamoto replies that he agrees that stents should be taken out quickly, however, stents in Japan tend to stay in longer than other countries.
This study is one of the first of its kind to look at stent encrustation ex-vivo that was previously put into a patient. Dr. Hamamoto and his team should continue to look at all the available stent compositions out there. In doing so, they will be able to conclude which material may be the least likely to encrust and therefore be influential regarding what stent a urologist might choose to insert into a patient. Additionally, reducing the likelihood of encrustation will help get rid of any complications that arise from encrusted stents.
Figure 1. Shows the three groups, their related stent material, coating, and a cross section of each stent.
Figure 2. graphs on their findings of Ca and Mg ions adherence to each stent material and bacteria adhesion to each.
Written by: Paul Piedras, B.S., University of California, Irvine, @piedras_paul on twitter, during the 2023 American Urological Association (AUA) Annual Meeting, Chicago, IL, April 27 – May 1, 2023
References:
- Mosayyebi A, Manes C, Carugo D, Somani BK. Advances in Ureteral Stent Design and Materials. Curr Urol Rep. 2018 Apr 10;19(5):35. doi: 10.1007/s11934-018-0779-y. PMID: 29637309; PMCID: PMC5893657.