The authors of this recent manuscript show an interesting Systematic Review and Meta-Analysis related with the new design of intraureteral stents. Although they are not new, in recent months the scientific evidence of their benefits versus a standard double pigtail ureteral stent has been increasing. As we have discussed in previous newsletters, the future of ureteral stents is to improve their adaptation to personalised clinical indications, to reduce the side effects of stents, and to achieve this it is necessary to assess new designs. The conventional ureteral stent has many well-known benefits, but it also has adverse effects that are closely related to its design. To briefly remind, there would be vesicoureteral reflux, as well as lower urinary tract discomfort related to the bladder pigtail. It is exactly these two problems that intraureteral stents are trying to solve. An important clarification, they are called intraureteral, but there is indeed a small bladder end, like a suture thread, for cystoscopic removal. So, they are not completely intraureteral as the title of the manuscript announces. In order to do so, they would have to be composed of biodegradable materials.

The aim of the current study is to assess whether intraureteral stents may reduce bothersome bladder symptoms by reducing foreign material in the bladder. Clinical studies comparing intraureteral stents with conventional ureteral stents and using the ureteral stent symptom questionnaire (USSQ) were analysed, a PRISMA-compliant systematic review was performed to identify comparative studies.

A total of 494 patients were evaluated with the following results: Urinary symptoms and pain scores were lower in the intraureteral stent group with statistical significance. General health and work performance domains were similar between the groups. A 2.5% stent failure or migration rate was reported in the intraureteral group compared to 0.3% in the conventional group, without statistical significance.

Therefore, the authors of the manuscript conclude that, intraureteral stents significantly decrease urinary symptoms and pain associated with conventional indwelling ureteral stents. However, further trials are needed to determine the optimal patient selection for this type of stent. This last statement is very important; What kind of patients can benefit from this stent design?

The authors of this manuscript carry out a systematic review (PRISMA methodology) aims to assess the current evidence concerning ureteric ‘stent on string’ (SOS) placed after ureteroscopy for stone disease in order to answer the question: Is SOS the new gold standard for post-ureteroscopy ureteric drainage in adult and paediatric patients? It should be remembered that this stent design was first described in 1986, however there is currently a paucity of literature concerning the SOS.

The authors included 8382 patients in the study with the following results: SOS showed several advantages in the comparative study, they were in situ for less time, with no difference in complications such as UTI or urinary symptoms. Further, significant cost savings, less pain on removal and high rates of safe home removal were reported in SOS. However, a small risk of stent dislodgement must be considered when making decisions regarding SOS placement following ureteroscopy. Therefore, SOS provides an excellent option following stone disease ureteroscopy, especially in those patients with no intraoperative complication. This is a very interesting option to further reduce prolonged ureteric stent placement, which is sometimes lengthened by logistical problems, and as we know is one of the main causes associated with ureteral stent morbidities, reduces the patients' quality of life, causing patient distress, loss of work, emergency room visits and infectious complications. Of course, this benefit of a shorter dwell time should not be underestimated.

These stents reduce dwell time, pain, and cost. While their use seems to be still restricted in the current endourology practices, they are likely to become the new gold standard for routine ureteroscopy in future, with more shared decision making and patient reported outcome measures coming into the mainstream.

The purpose of this clinical study is to evaluate the rate of and predictors of stone passage after urgent retrograde stent placement for “symptomatic ureteral lithiasis”. It is well-known that surgical stone removal is not always mandatory after ureteral stenting. The reasons are linked to an effect associated with ureteral stents, which is passive ureteral dilatation, related to the complete inhibition of ureteral peristalsis, a circumstance that favor’s the passage of ureteral lithiasis. This study was motivated by the lack of standardized postprocedural management of patients submitted to emergency stent placement for ureteral stones.

The authors retrospectively analysed data from 249 consecutive patients presenting to the Emergency Department for “symptomatic ureteral stones” and treated with retrograde ureteral stent placement. Study variables were: stones parameters before stenting and stone passage evaluated at 1 month with CT. Alpha-blockers were not prescribed after ureteral stenting, while analgesics were used as needed.

Stone diameter were 4.4-9.8 mm. Stone passage was observed in 26.2% of patients. Stone diameter (3.2 vs. 7.7 mm, p < 0.001) and stone density (416 vs. 741, p < 0.001) were lower and a higher rate of distal stones (76.9% vs. 26.7%, p < 0.001) was found in the stone passage group compared with persistent stones. Multivariable logistic regression analysis showed that distal ureteral stone location and lower Hounsfield units (HU) were associated with stone passage, after accounting for stone volume. It is important to highlight that in this study patients with a distal stone of 500 HU had a 75% probability of stone passage.

The authors conclude this retrospective study by confirming that one out of four patients treated with ureteral stent for symptomatic ureteral lithiasis had stone passage 1 month after stenting. Distal stone location and lower stone density were found to be independent predictors.

The authors therefore propose a composite risk score based on stone location and density that accurately identifies patients at higher risk of stone passage after ureteral stenting. Patients with these criteria should be managed with follow-up imaging and stent removal instead of ureteroscopy with laser lithotripsy.