In 1967, Dr. Paul Zimskind first reported using ureteral silicone tubing as an indwelling stent. In theory, these stents were to provide aid with drainage for up to 19 months however, some were expelled due to the absence of a mechanism to prevent stent migration . Seven years later, Gibbons presented a silicone stent equipped with a distal flange and sharply pointed barbs to prevent upward and downward migration, respectively. Nonetheless, this design was difficult to insert into patients because the barbs increased the stent size from 7 Ch to 11 Ch . Then in 1978, Roy P. Finney presented the double pigtail silicone stent design that most resembles the ureteral stents used in practice today.
Ureteral stents are mainly used to relieve urinary obstruction and are used in a variety of cases such as obstructing stones, strictures, and aid in effective drainage . Despite their benefits, over 80% of patients with indwelling ureteral stents experience stent-related pain that affects their ability to perform daily activities, causing at least one-third of patients to prematurely remove their ureteral stents . Premature removal of ureteral stents can alternatively affect patient recovery and lead to more post-operative complications. Thus, to improve surgical outcomes and patient health, it is important to limit SRS. In a study conducted by Lennon et al. , it was concluded that the softness of the ureteral stent directly influenced patients’ tolerability; stents made from softer material correlated with less incidence of dysuria and pain . Additionally, in a recent study found that silicone ureteral stents were associated with less patient discomfort at day 20 Post OP . Therefore, in order to further reduce SRS, alterations to stent composition could be a solution.
In this study, the intensity of SRS in traditional polyurethane ureteral stents and modern silicone ureteral stents were compared. From the data, use of the OAB awareness tool proved unfit to accurately assess patient QoL. However, VASP data concluded that patients who received silicone ureteral stents had a significantly better QoL in the middle of the stent indwelling period and immediately prior to stent removal compared to those who received polyurethane ureteral stents (p = 0.023 and p = 0.014, respectively).
Despite these findings, some studies have not found a correlation between stent material composition and patient QoL [27,28,29]. Due to these inconsistent findings, additional long-term research studies should be completed before any conclusive statements can be made regarding stent material and the affect it has on QoL. Nonetheless, none of these studies specifically compared silicone ureteral stents to polyurethane stents. This could be mainly due to recent advancements in modern technology that have made it possible to manufacture silicone ureteral stents with the same external diameter, internal diameter, and size of side holes as in polyurethane ureteral stents. Due to these advancements our study displayed the superiority of silicone ureteral stents in terms of body pain at 2 weeks before stent removal and immediately before stent removal.
Comparing stent-related complications from both Group A and Group B, no significant difference was observed. These results speak to the overall safety of silicone ureteral stents. Originally, silicone ureteral stents were replaced with polyurethane ureteral stents due to low tensile strength which limited the internal diameter and aperture of side holes. Additionally, silicone ureteral stents proved more difficult to place due to a high volume of friction and were more expensive to produce leading to the switch to polyurethane ureteral stents . Because of recent technological advancements, silicone stents are beginning to become more similar to traditional polyurethane ureteral stents in both size and safety. In our study there was no significant difference in the stent encrustation rate. This could have been due to the small sample size used and short duration of the study limited to 4 weeks. A larger sample size and longer study duration should be used to accurately determine if stent encrustation would differ between polyurethane and silicone ureteral stents.
Thus, silicone ureteral stents may be a viable option for patients who have had a previous negative experience with polyurethane ureteral stents or could alternatively be used as a replacement stent for patients with current indwelling polyurethane ureteral stents experiencing SRS. However, silicone ureteral stents depending on country can be more expensive than polyurethane ureteral stents as in Russia, which can be an obstacle receiving such stents.
Our study did have some limitations: it was a non-randomized study with a small sample size which may have affected our study results. Additionally, groups differed in terms of stone size which could possibly affect successfulness of stent placement. One of the instruments for assessment of SRS was OAB awareness tool, which is not very popular but has Russian validated translation. Further research is needed to confirm the results of our study.