#04 Click here to see the previous editions November 4, 2023
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Welcome to STENT News! In this newsletter, we will cover about the most relevant evidence in the use and development of stents, catheters and another indwelling urological devices. Stay tuned for updates and insights on this important topic.

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Dear Stent Fans. Welcome to this issue of Stent News.

In our fourth newsletter, we have three interesting papers on ureteral stents that I hope will be of interest to you.

The first is a translational study in which the authors describe their in vitro and in vivo studies of a biodegradable Rapamycin-eluting stent to modulate ureteral wall healing and prevent recurrence of strictures. These lines of research are the ones that in the near future could improve the results of stents, reduce their adverse effects and modulate the urinary environment. Such as the release of local chemotherapy in the upper urinary tract, control of ureteral healing, etc. In a second manuscript, the authors evaluate a topic of ongoing debate, the optimal stenting time after uncomplicated ureteroscopy. Extending the stenting duration is always related to increased adverse effects and also to increased complications of ureteral stents. Finally, the last selected paper deals with the management of stone patients with bleeding disorders or anticoagulation therapies, a topic of great interest. The assessment of whether prior ureteral stenting can be beneficial and reduce bleeding complications.

I hope they will be of interest to you.

img In vitro and in vivo assessment of a bilayered degradable Rapamycin-eluting stent for ureteral stricture caused by Holmium:YAG laser lithotripsy. Acta Biomater. 2023.
Hu J, et al.
img 3'
https://pubmed.ncbi.nlm.nih.gov/37821034/ img

The authors of this manuscript show an interesting translational study in a disease such as ureteral stricture, one of the most challenging for urologists. Unfortunately, the treatment of ureteral strictures depends on many factors (their length, stricture location, stricture type, duration, renal function, etc.). This is exacerbated when treatment is performed by endourological approach, as in this scenario ureteral healing is based exclusively on second-intention healing. This increases the risk of recurrent stricture, due to inadequate remodelling of the ureteral wall with fibrosis and excessive collagen deposition.

One of the objectives of researchers in ureteral stents is to take advantage of these devices for the release of drugs, in this case a biodegradable ureteral stent that releases a drug, rapamycin, to modulate the healing of the ureteral muscular layer. The efficacy of the scaffold was subsequently confirmed through in vitro and in vivo experiments. The collagen, fibronectin and a-smooth muscle cells expressions in fibroblasts are down-regulated by blocking mTOR pathway. Rapamycin particularly inhibited the activity of mTORC1 and thus inhibited proliferation and migration of a-smooth muscle cells.

For in vivo results, rat bladder, of 28 days, the biodegradable bilayered stent maintained structural integrity and reduced deposition of crystals, thinner and less lamina propria connective tissues. The comparative in vivo study demonstrated the outstanding effect of drug-eluting stents compared with standard ureteral stents on inhibiting hyperplasia of ureteral scar. It is a further step in the design of ureteral stents that allow the release of drugs to modulate physiological pathways, in this particular case the second-healing intention of the ureteral wall, by avoiding recurrent stricture.

img Timing of Ureteral Stent Removal After Ureteroscopy on Stent-Related Symptoms. A Validated Questionnaire Comparison of 3 and 7 Days Stent Duration. J Endourol. 2023.
Heidenberg D, et al.
img 3'
https://pubmed.ncbi.nlm.nih.gov/37885220/ img

The authors of this recent paper assess in a controlled clinical study an issue of ongoing debate among endourologists, that is the optimal time to stent removal after uncomplicated ureteroscopy. There is currently controversy as to whether ureteral stenting is necessary after uncomplicated ureteroscopy. The aim of this decision is clear, to promote ureteral dilation, to allow passage of smaller stones, debris and blood clots. Moreover, surveys of urologists reveal that 64% of urologists always place a stent. There is no scientific evidence about the optimal timing of stent removal, practice patterns can vary from days to weeks. AUA guidelines recommend that the duration of the ureteral stenting after uncomplicated ureteroscopic intervention for stones should be three to seven days.

Author´s aim was to determine if urinary symptoms were significantly improved with three days versus seven days of stent placement without an increase in complications, using a validated USSQ questionnaire. Ureteral stent symptom questionnaire were filled out on postoperative day two and two days after stent removal. A methodological strength of the study is that a single urologist performed the study, avoiding technique bias, but could reflect selection bias.

The group of patients with seven days of stenting duration reported greater urinary symptoms and pain with stents in situ compared to the three-day patients, with statistical significance. Urinary symptoms, pain and general health were more severe in Group seven days after stent removal as well. The analysis also revealed that urinary symptoms, pain, and general health improved after stent removal compared to stent in situ (p<0.001). There were no significant differences in work-related functioning between two groups. There were no significant differences in emergency department visits, unplanned clinic visits or hospitalizations between patients’ groups.

Results indicate that the three day stent patients group had improved ureteral stent related-symptoms as urinary symptoms and less pain averaged with both of the stents in place and after stent removal compared to the seven day group without increased complications. Therefore, this protocol could be included in this type of patients with uncomplicated ureteroscopies, when more randomized, multicentre and prospective studies are done.

img The effect of pre-stenting on bleeding-related complications following ureteroscopy in patients on anticoagulation or antiplatelet therapy. J Endourol. 2023
Berger JH et al.
img 3'
https://pubmed.ncbi.nlm.nih.gov/37675902/ img

There is a large population of patients using daily anticoagulation or antiplatelet therapy. Clearly, the combination of this antithrombotic therapy in patients with lithiasic disease represents a treatment challenge. The EAU and AUA guidelines describe ureteroscopy as a low-risk bleeding procedure, unlike shock wave lithotripsy, percutaneous nephrostomy or percutaneous nephrolithotomy which are high-risk bleeding procedures.

The current multi-institutional retrospective study sought to determine whether prior ureteral stenting in patients on antithrombotic therapy was associated with fewer URS-related bleeding complications. This strategy is based on the assumption that pre-URS ureteral stenting may result in improved operative outcomes. This circumstance is rarely assessed in this particular kind of patient.

A total of 293 identified URS procedures were completed in patients on anticoagulant or antiplatelet therapy. 112 cases were on anticoagulation therapy only (38 were pre-stented), 158 on antiplatelet therapy only (51 pre-stented) and 23 on both (8 pre-stented). The authors evaluate intraoperative and 30-day postoperative outcomes (intraoperative bleeding, postoperative haematuria, emergency department visits, hospital readmission, unplanned reoperation, telephone calls and other minor complications at 30 days).

For anticoagulation and antiplatelet therapy subjects, pre-stenting did not decrease the composite risk of bleeding complications, 10.3% pre-stent versus 12.2% non-pre-stent. Pre-stented patients did have a significantly lower likelihood of requiring an unplanned reoperation, 1.0% versus 5.6%. In the subgroup of patients on antiplatelet therapy alone, pre-stented patients had significantly fewer episodes of intraoperative bleeding, unplanned reoperations, and 30-day complications. In the subgroup of patients on anticoagulation therapy alone, there were no significant differences in outcomes based on stent status.

The authors conclude that pre-stenting before URS was not associated with fewer bleeding complications in a mixed cohort of patients. However, pre-stenting appeared to be associated with improved outcomes, decreased intraoperative bleeding and need for reoperation, for those patients on antiplatelet therapy. Therefore, the role of pre-stenting after URS in this kind of patients and treatments needs to be further evaluated.

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