Hello and welcome to the Stone News, a newsletter where we discuss every three months the most recent and relevant studies in stone disease.

Suscribe now

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

The first focuses on the relationship that appears due to prolonged preoperative double J stenting, which may increase post-ureteroscopy infectious complications. Their findings underscore the importance of minimizing stent dwell time through expedited surgical scheduling to avoid infectious complications. 

Secondly, an interesting clinical study on the management of ureteral strictures using metallic ureteral stents coated in refractory ureteral stricture, with an outstandingly long follow-up period and very positive results, except in cases of ureteral strictures caused by radiotherapy. 

Finally, a manuscript related to the management of forgotten ureteral stents and whether there are differences between paediatric and adult patients. Forgotten ureteral stents can cause life-threatening complications in both pediatric and adult patients due to encrustation and stone formation.

3'

The authors of this retrospective, single-centre study assess an interesting aspect related to preoperative ureteral stents, although there is currently little scientific evidence to support clinical decision-making.

It´s a common practice, particularly in the setting of obstructive uropathy or infection temporary ureteral double pigtail stenting is employed preoperatively to decompress the urinary tract and facilitate access during ureteroscopy. However, procedural delays due to logistical or institutional constraints can lead to prolonged stent indwelling, which may increase the risk of bacterial colonization, urinary tract infection, and postoperative infectious complications. Therefore, the aim of this study was to evaluate whether prolonged preoperative ureteral stenting is independently associated with an increased risk of postoperative infectious complications following ureteroscopy. Identifying this potential risk factor could support the implementation of fast-track surgical pathways aimed at reducing unnecessary stent dwell time and improving clinical outcomes.

A total of 350 patients were involved in the study, 70% of whom were men (a limitation of the study, but this overrepresentation reflects the known epidemiological pattern of higher urolithiasis prevalence in men). The primary outcome was infectious complications. The most noteworthy findings of this interesting manuscript were: 63% of preoperative urinary culture was sterile urine; the median time from culture to ureteroscopy was 7 days, which is a very interesting fact; antibiotic prophylaxis most common was cefuroxime.

Postoperative infectious complications occurred in 8.3% patients. Infectious complication occurred in 6% of patients with dwell time <30 days; 5.5% in the 31-60 day group, and 21.4% in those with stents left in place for more than 60 days. The results demonstrate that prolonged stent duration before ureteroscopy is significantly associated with increased postoperative infectious failure, with particularly notable rise in infection risk beyond 60 days of indwelling time. This suggests an interesting threshold with clinical application (<60 days). The indwelling stents act as a nidus for bacterial colonization increasing the risk of urinary tract infections and sepsis following endourological procedures. We must remember that biofilm bacteria can survive antimicrobial drugs at concentrations 1,000–1,500 times higher than the concentration that kills planktonic bacteria of the same species.

These findings underscore the importance of minimizing stent dwell time through expedited surgical scheduling to avoid infectious complications.

3'

Refractory ureteral stricture is characterized by the resistance to conventional curative therapies or the ineligibility for such treatments and represents a persistent clinical challenge for urologists. Furthermore, the timely management of these strictures are crucial, as untreated or inadequately addressed cases can progressively impair ureteral patency and renal function, leads to a deterioration in patients' quality of life and significantly increases the cost of treatment for patients.

The minimally invasive surgery have shown relatively lower long-term success rates of 50%-60%. In addition, percutaneous nephrostomy and pigtail ureteral stents in the maintenance treatment require frequent exchanges and cause several complications that seriously impair patients’ QoL. One of the solutions in endourology over the years has been covered metal ureteral stents have emerged as a promising maintenance treatment.

Unfortunately, there are no long-term studies in the scientific literature. The longest studies are 1 year and 2 years with metal-coated stents and reported that the 1-year and 2-year success rates for the management of ureteral stricture were 73.2% and 71.7%, respectively.

The authors of this manuscript propose a prospective and multi-center cohort study aimed to investigate the long-term clinical efficacy and safety profile of covered metallic stents in the maintenance treatment of refractory ureteral stricture, assess patients’ QoL, and explore risk factors for stents-related complications.

This is great news for readers who are eager to learn about prospective, long-term studies on this kind of strictures, which is so difficult to manage in daily clinical practice.

321 patients with 366 renal ureter units were included. The median length of ureteral stricture was 7.0cm, which implies an extremely long stricture.

Compared with the preoperative USSQ total scores with double-J ureteral stents, the USSQ total scores at both postoperative 12 and 36 months with metallic stents showed statistically significant decrease. There were 26.0% with covered metallic stents -related complications, including 6.6% with end-stent ureteral restenosis, 7.7% with stent migration and 8.5% with stent encrustation. Patients in the cohort of radiation induced ureteral stricture experienced the highest complication rate 45.3%. The 3-year primary and secondary ureteral patency rate was 74.0% and 90.4%, respectively.

However, among patients with radiation induced stricture, the primary and secondary ureteral patency rates were only 54.7% and 77.4%, respectively In conclusion, covered metallic stents are effective and safe in the 3-year maintenance treatment of refractory ureteral strictures. Patients experience long-term improved QoL. However, patients who underwent radiotherapy are susceptible to developing stent-related complications. This is excellent news for the management of this type of patient, except for those undergoing pelvic radiotherapy, as it ensures a high success rate that is maintained in the long term.

3'

The authors report an interesting retrospective study on a condition that, although rare, is clinically challenging to manage: forgotten ureteral stents. Studies showed that forgotten ureteral stents can cause complications such as obstruction, hydronephrosis, stone formation, migration, encrustation and also renal failure, sepsis and even death. The authors conduct a study on the treatment and management of forgotten ureteral stents in the paediatric age group versus adults. The primary objective of the study was to evaluate treatment strategies and outcomes.

For the assessment of stent encrustation, the following was used: the FECal grading system based on its location and extent, as follows. A total of 115 patients were included in the study. There were 37% patients in the pediatric group and 63% patients in the adult group.

The total number of procedures for each stent was significantly higher in the pediatric group, 2, compared to the adult group, 1. Grade 2 complication rates according to the Clavien classification were significantly higher in the pediatric group. As expected, the number of procedures required for Double-J stent removal increased in parallel with higher FECal grades, giving us an idea of how appropriate this score is. With regard to clinical presentations, adults show greater hydronephrosis and haematuria than paediatric patients, but more fever and sepsis in children. In children, the most common treatment was ureteroscopic lithotripsy, and in adults, percutaneous treatment was also widely used.

This study is the first in the literature to compare pediatric and adult forgotten ureteral stent patients. In this study, both groups showed a similar stent indwelling time of approximately 2 years. This is clearly consistent with previous studies that show that encrustation will increase with the increased indwelling time of the JJ stent and more complicated surgical procedures will be required for removal.

Unfortunately, there is no consensus on a definitive method of removal or, rather, there is no clear treatment algorithm. However, it is clear that the therapeutic approach depends on the imaging findings, especially stone encrustation, stone size, stent migration or fragmentation and of course renal function.

Forgotten ureteral stents can cause life-threatening complications in both pediatric and adult patients due to encrustation and stone formation. In addition, the number of fragmentation and the total number of procedures required to remove the stent may be greater in pediatric patients than in adults.

There are numerous apps, monitoring systems to prevent these serious complications, which also increase healthcare costs related to the removal of ureteral stents by up to six times.