Outstanding review of the recent evolution and future applications of biodegradable ureteral stents (BUS), in which recent advances in BUS in the last five years are evaluated. The article shows some very illustrative tables that facilitate the understanding of the review and are very much appreciated for their explicative quality; it is worth taking the time to read it.
 
The study describes in depth the technology applied for the development of BUS, starting with the description of the new biodegradable materials used: natural polymers as alginate, gelatin, silk fibroin and chitosan. As well as synthetic polymers: PCL, PGA and PLA. However important studies are also being carried out on metallic materials that have greater inherent antimicrobial activity and superior mechanical properties than polymer-based materials. Mainly, Magnesium and Zinc and their alloys.

Another important aspect addressed in this review is the innovation in drug delivery system technology (drug eluting stents) in BUS. This is currently one of the major fields of research in this discipline. The importance of biodegradable ureteral stents, which avoid the need for cystoscopic removal of the stents as well as the possibility of stent-forgotten syndrome. In addition to the already known features of the ureteral stent: facilitating drainage of the upper urinary tract and its scaffold function, the aim is to be able to deliver drugs locally. Finally, the authors describe precisely the future clinical application of BUS, related to prevention of stent encrustation, antibacterial properties, treatment and prevention of carcinoma, postoperative discomfort and pain management, prevention and treatment of ureteral strictures.

One important conclusion of the authors relates to the in-depth exchanges and communication between clinicians and material science experts will accelerate the development of BUS. The interdisciplinary cooperation and learning of biomaterials and medicine are inevitable in the development of BUS in the future.

The authors report a large retrospective study evaluating 117 consecutive patients who underwent implantation of retrievable covered expandable metallic stent to identify prognostic factors for stent migration, including stricture location and length, hydronephrosis-cortex ratio, ureteral dilation, and the diameter of the narrowest portion of the stricture. The great interest of this manuscript is that there is scarce scientific evidence on this issue and although the use of metallic stents could be a successful treatment solution for very selected patients, their use is greatly reduced due to current weaknesses, one of them associated with high migration rates. Identifying these causes will allow us to increase their use and better select the target population that can benefit without increasing their risks.

The results show that stent migration occurred in 19.5% of patients. Stent migration is more likely to occur in patients with the following prognostic factors for migration: distal ureteral stricture, patients who underwent balloon dilation, hydronephrosis-cortex ratio ≧10, larger diameter of wasting of metallic stents, and patients with a shorter stricture length. Knowledge of these factors will reduce the adverse effects of ureteral metal stents designed for endourological removal.

It is important to remember that after ureteral stenting, about 80% of patients experience urinary tract symptoms and pain, 58% show decreased work performance and 32% experience sexual dysfunction. The authors describe an interesting systematic assessment of the therapeutic efficacy and complications of Tolterodine and α-adrenergic receptor blockers in alleviating ureteral stent-related symptoms. 

Since the urinary symptoms caused by stents are similar to those caused by overactive bladder and benign prostatic hyperplasia, previous studies have explored the use of α-adrenergic receptor blockers and antimuscarinics to treat ureteral stent-related symptoms. Currently, the main α-adrenergic receptor blockers used to alleviate ureteral stent-related symptoms include Tamsulosin, Alfuzosin, and Terazosin. Recent research has shown that the use of Tolterodine can improve urinary symptoms in patients after ureteral stenting, and for this reason the authors performed this systematic review, as many studies have not reached a consistent conclusion on their own.

After rigorously fulfilling the criteria for inclusion, the authors included eight studies to evaluate the efficacy and safety of Tolterodine and α-adrenergic receptor blockers for the treatment of ureteral stent-related symptoms. This is the first meta-analysis utilizing USSQ scores to comprehensively assess the efficacy and complications of α-adrenergic receptor blockers and Tolterodine as monotherapy for relieving symptoms associated with ureteral stents.

The results of this manuscript revealed that compared to Tolterodine, α-adrenergic receptor blockers demonstrated statistically significant advantages in alleviating bodily pain, while Tolterodine exhibited superior effects in enhancing work capacity. The incidence of dry mouth was significantly higher in patients receiving tolterodine treatment than in α-adrenergic receptor blockers.