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Dear stent friends, once again a newsletter of our ureteral stents series. I have chosen from the most recent scientific literature three very interesting papers. 

Firstly, a clinical study, which is in fact the case for the three selected papers, focused on the comparison of soft stents versus firm stents. This prospective, randomised, single-blind clinical trial comparing symptoms related to the use of soft and rigid ureteral stents provides very interesting information that confirms the findings of other studies, namely that soft stents provide greater patient comfort and are not associated with complications. It therefore encourages their use to reduce complications associated with ureteral stents. 

On the other hand, an interesting study by a Canadian group has designed and validated a new score/questionnaire to assess the effects of stents and patients' quality of life and compare it with the USSQ, which is the gold standard for this objective. 

Finally, a manuscript relates stent diameter to quality of life in kidney transplant patients, confirming the hypothesis and trend that smaller diameter stents allow drainage and scaffolding objectives to be met and reduce adverse effects and pain in these patients. I hope you find them interesting.

3'

An interesting paper introduces a new questionnaire for symptoms associated with ureteral stents, which aims to challenge the classic questionnaire designed and validated by Joshi in 2003, the USSQ (38 items). The authors present the CEGSSS, a brief questionnaire with only 11 items that assesses symptoms related to ureteral stents in short-term use (<2 weeks). This is a very interesting issue, as short-term use is most common after ureteroscopy and lithotripsy, as endorsed by the EAU guidelines.

The structure of the CEGSSS questionnaire consists of three main domains: urination, pain, and quality of life related to the stent. These domains emerged after exploratory factor analysis and consensus with experts, reflecting the most relevant and clinically significant aspects in the assessment of symptoms in patients with short-term ureteral stents. Its reliability was validated in multiple North American health care centers with a population of 287 patients.

The results showed strong internal consistency, reliability in retesting, and sensitivity in detecting changes in symptoms over time, in addition to having a response time of approximately 4 minutes compared to 13 minutes for the USSQ, the previous standard assessment tool. This last aspect related to response time is an important advantage, since with regard to the USSQ, all scientific literature shows that it is one of the barriers to patients responding adequately, with subdomains always remaining unanswered.

Reliability was satisfactory, with Cronbach's coefficients between 0.60 and 0.81. This questionnaire showed a strong correlation with the USSQ in the domains of urination and pain, although less so in quality of life, reflecting differences in the aspects evaluated. Sensitivity to change allowed significant improvements in symptoms to be detected after stent removal, confirming that the questionnaire can monitor clinical progress in patients with stents in short-term use.

The CEGSSS therefore represents several improvements over the USSQ, notably its short length, as it can be completed in approximately 4 minutes compared to 13 minutes for the USSQ, which may increase patient acceptance and compliance in clinical studies and hospital settings. In addition, it is specifically designed for patients with short-term stents (<2 weeks), which represent current clinical practice, unlike the USSQ, which was developed for long-term stents and is less useful in short-term situations. Furthermore, its patient-centered approach and focus on clinically relevant aspects make it more useful and accessible, facilitating its use in populations with lower health literacy.

It remains to be seen whether other hospitals will assess its validity and whether its use will spread, providing information on patients with ureteral stents in a simpler way.

2'

This interesting study reinforces previous manuscripts comparing soft ureteral stents versus firm ureteral stents. In this case, it is a robust and well-designed prospective, randomised, single-blind clinical trial comparing symptoms related to the use of soft and rigid ureteral stents in 120 patients undergoing ureteroscopy and lithotripsy of kidney stones. Symptoms were assessed using the Ureteral Stent Symptoms Questionnaire (USSQ) at the time of stent removal, 14 days after endourological surgery.

The most interesting results show that patients with soft stents reported significantly fewer stent-related symptoms compared to those with rigid stents. The soft stent group had an average USSQ score of 26, while the rigid stent group had a score of 73, which was statistically significant.

Soft stents showed better results in all USSQ subdomains, including urinary symptoms, pain, general health, work performance, and sexual performance. The main reason why soft stents cause fewer symptoms lies in the differences in the materials and physical characteristics of the stents. Soft stents are more flexible, which reduces urothelial irritation in the ureter and bladder, decreasing symptoms such as pain, urinary urgency, dysuria, and haematuria. The flexibility of soft stents allows them to better adapt to the anatomy of the urinary tract, reducing pressure and friction on the walls of the ureter and bladder.

Therefore, according to this paper, soft ureteral stents significantly reduce stent-related symptoms compared to rigid stents, improving patients' quality of life without compromising safety. The recommendation for the use of soft stents after ureteroscopy and lithotripsy of uncomplicated stones is strong. Only in cases of problems ascending a ureteral stent or due to some type of compression would the use of firm stents be a good indication.

3'

We return to a topic that I sincerely believe has become clearer over the years, specifically the impact of stent diameter on upper urinary tract drainage and also on the symptoms associated with stents in patients. This manuscript reinforces previous studies and focuses on kidney transplant patients.

To this end, the authors carried out a prospective randomised controlled trial in which 70 kidney transplant recipients received a 4.8 Fr or 6 Fr ureteral stent, using the Ureteral Stent Symptom Questionnaire (USSQ) and the Visual Analogue Scale (VAS) to assess symptoms. The study compared early postoperative outcomes and patient-reported symptoms between 4.8 Fr and 6 Fr ureteral stents, as there is very limited evidence directly comparing the effect of stent diameter in kidney transplantation.

Therefore, we must ask ourselves: do ureteral stents reduce serious urological complications in kidney transplant recipients?

The results of numerous studies show that the routine use of ureteral stents in patients undergoing kidney transplantation leads to a significant decrease in major urological complications. In fact, the use of ureteral stents reduces the incidence of complications from 9% to 16% to 1.5%. A Cochrane review found that while ureteral stents can reduce the risk of urological complications by up to 76%, they can also increase the risk of urinary tract infections by 49%. When it comes to the EAU guidelines on kidney transplantation, there is one STRONG recommendation: use transplant ureteral stents prophylactically to prevent serious urological complications.

Scores for stent-related symptoms, USSQ, and pain intensity (VAS) were significantly lower in the 4.8 Fr group compared to the 6 Fr group. The incidence of postoperative urinary tract infections was comparable (25.7% in the 4.8 Fr group vs. 20.0%), and there were no significant differences in major urological complications, such as urinary leakage. Safety was not compromised with the smaller diameter stent, as rates of urinary leakage, ureteral obstruction, and UTI were similar between groups, suggesting that reducing stent size does not increase infectious or anastomotic complications.

The findings support the use of smaller-caliber ureteral stents as a well-tolerated and safe option for improving postoperative comfort in kidney transplantation, although larger multi-center trials are needed to validate the long-term results.

Smaller stents have already been shown to cause less discomfort and provide drainage of the upper urinary tract that is equal to or better than stents with larger diameters, since after the first 48 hours post-stenting, drainage is predominantly periprosthetic, meaning that smaller diameter stents have a higher ureteral lumen ratio.