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Dear stent friends, once again a newsletter of our ureteral stents series. As usual, I have selected from the most recent scientific literature three very interesting papers. The three manuscripts address different aspects relating to double-J ureteral stents and share the common feature that they are not clinical studies, but rather focus on reviews or editorial commentaries. They provide updates on topics of great interest in endourology, such as the optimal duration of stent placement and methods of removal; the indications for double-J stent placement; and the future of ureteral stents.

I hope you find them interesting!

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Ureteral stents are routinely used following endourological procedures, however, stent-related morbidity remains common, and optimal stent dwell time and removal methods are not well defined. The authors present an interesting systematic review on these two topics. Prolonged indwelling duration has been consistently associated with higher risks of encrustation and technical difficulty at removal, whereas premature removal may increase the risk of ureteral colic or unplanned healthcare encounters.

The systematic search identified 32 studies representing a cumulative study population of 4,373 adult patients, which gives an idea of the importance of this review.

This is what we can learn for daily clinical practice. Reported stent dwell times varied widely, most commonly ranging between 10 and 14 days in uncomplicated cases, with longer durations associated with increased rates of encrustation and removal difficulty. This interval is widely perceived as a pragmatic balance between ensuring ureteral patency and limiting stent-related morbidity. Unfortunately, these data indicate that shorter dwell times can be achievable, the current evidence does not reliably clarify which clinical or intraoperative factors. In particular, operative complexity, ureteral trauma, and postoperative infectious risk were inconsistently reported, limiting the ability to translate feasibility findings into determinant-based recommendations. 

Removal techniques included rigid cystoscopy (48.7%), flexible cystoscopy (19.9%), ureteral strings stents (23.5%), and device-assisted methods (including magnetic or ultrasound-guided techniques) (7.9%). Less invasive approaches, particularly flexible cystoscopy and extraction-string removal, were consistently associated with reduced pain scores and improved patient comfort, although extraction strings carried a small risk of early dislodgement. About string stents, authors emphasizing the need for careful patient selection, counseling, and clear postoperative instructions.

High encrustation prevalence in cohorts with dwell times exceeding one month underscores dwell time as the most consistently identified modifiable factor associated with biomaterial-related complications and challenging removals.

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European guidelines recommend that ureteral stents be placed after ureteroscopy in patients at increased risk of complications, such as those with ureteric trauma, perforation, residual fragments, bleeding, solitary kidney or pregnancy. The EAU section of endourology provide an up-to-date summary of ureteral stents indications and summarise the data regarding its frequency of insertion.

The indications for stent placement can be categorised into elective and emergency indications. Elective indications include prior to, or following, URS, PCNL or ESWL. Other elective indications include, but are not limited to, chronic ureteral obstruction and reconstructive surgery. Emergency decompression of the upper urinary tract with ureteral stents remains a mainstay of management of patients with ureteric obstruction. 

Ureteroscopy: Routine pre-ureteroscopy stenting is currently not recommended. Despite the potential benefits of pre-URS stents insertions, the costs must be considered, both in terms of patient QoL and financial aspects. As the role pre-URS stent placement is to passively dilate the ureter, alpha-blockers could provide a less costly and less invasive method of achieving this in patients. If access to the ureter is not possible, then stent placement and a repeat procedure in one/two weeks is recommended.

As we are well aware, routine stenting post uncomplicated URS is not recommended. Despite this, because the definition of an ‘uncomplicated’ URS is subjective, placement of a stent is often performed either out of concern for postoperative complications or out of habit.

Percutaneous nephrolithotomy: The decision to place a double J stent following PCNL depends on several factors, including residual fragments, the likelihood of a second-look procedure, intraoperative bleeding, urine extravasation, ureteric obstruction, potential persistent bacteriuria due to infected stones, solitary kidney, bleeding diathesis, or planned percutaneous chemolitholysis. To be honest, the decision is also dependent on the urologist.

Before extracorporeal shockwave lithotripsy: Historically, stenting placement before ESWL was commonplace. However, this is now far less common, as data have shown that pre-ESWL stenting does not improve SFRs or reduce complications. Therefore, decision-making should be individualised, taking the stone burden and clinical context into account.

There is now international consensus amongst guidelines that ureteral stents are omitted following uncomplicated ureteroscopy. Despite this, recent studies have shown that stents are still inserted following the majority of URS, ranging from 64–86%.

Lastly, with the global ureteral stent market expected to nearly double between 2022 and 2032 and with exciting improvements and developments in ureteral stents design and biomaterials, double pigtail stents are here to stay for the foreseeable future.

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Despite their widespread use stent-related morbidity, commonly termed stent-related symptoms (SRS), continues to pose a substantial challenge in routine clinical practice. SRS encompasses a heterogeneous group of clinical manifestations and the aetiology of these symptoms is multifactorial and includes mechanical irritation of the bladder and trigone, vesicoureteral reflux, activation of nociceptive pathways, and local inflammatory responses. Beyond the symptomatic burden, stent encrustation represents a clinically relevant complication and bacterial/biofilm colonisation on the stent surface further contribute to stent-associated morbidity. We must remember that biofilms promote antibiotic resistance, hinder infection eradication, and increase the risk of severe complications such as urosepsis.

The authors of this editorial present innovative strategies for mitigate SRS and reduce stent-related complications.

Optimisation of stent design: Modifications in stent shape, particularly at the distal end, have shown potential to reduce bladder irritation and vesicoureteral reflux. The aim of these new designs is to minimise contact with the vesical trigone and also to prevent vesicoureteral reflux, which is caused by the placement of a double-pigtail stent that dilates the vesicoureteral junction and blocks the action of the urinary sphincter.

Selection of advanced biomaterials: The biomaterials used in stent fabrication significantly influence biocompatibility, resistance to encrustation, and susceptibility to bacterial colonisation. Currently, silicone and polyurethane remain the most used materials. In recent years, silicone has demonstrated that it has overcome the limitations that led to a decline in its use in the 1980s. Silicone has shown lower encrustation rates and improved biocompatibility, making it a good option for patients with long-term stent placement or for replacements required due to patient discomfort. Surface coatings have also emerged as a viable strategy to reduce biofilm formation and SRS, although the clinical results are not yet conclusive.

Development of drug-eluting stents: The incorporation of pharmacological agents into the ureteral stent matrix, allowing controlled local drug release, represents an innovative approach to reduce pain, inflammation, infection, and even provide instillation of cytostatic drugs into the urinary tract.

Biodegradable stents: Designed to dissolve within the urinary environment by hydrolysis, offer the advantage of eliminating the need for secondary procedures for stent removal,thereby reducing patient burden, complication rates, and healthcare costs. This research is currently still at the experimental phase, but advances in this field are now being translated into clinical trials, having overcome the limitations of these medical devices-such as degradation rate control and ensuring that the fragments are small enough not to cause any obstruction.