Ureteral stents are widely used in urological practice and nowadays represent an irreplaceable tool for urologists to treat patients with ureteral obstructions.
The present study is the first to systematically analyze reports from the MAUDE database. According to our results the most common problems are break (23%), material problems (14%) and calcification (8%). Moreover, AEs were analyzed per manufacturer highlighting different safety profiles between them.
The perfect stent should meet several criteria including easy insertion and removal, easy manipulation, resistance to encrustation and migration, biocompatibility, radio-opacity, biodurability, cost-effectiveness and tolerability[10].
Urolithiasis represents the main field of application of ureteral stents, in fact these devices are considered both as a treatment and as an act of prevention of renal colic, therefore it is routinely used both in the pre-operative as in the post-operative setting of a lithotripsy[11]. Nevertheless, the indications for the placement of a stent are extremely wide and include also chronic conditions which require periodical replacement of the device every 3–6 months. Ureteral stents accidentally left in situ indefinitely, commonly dubbed “forgotten” stents, can have severe consequences. The forgotten stent has proven to be a recurring source of morbidity in urology patients. These stents may serve as a nidus for urinary stone formation in a period of weeks to months and may result in the formation of large renal calculi and bladder stones [12]. Singh et al. [13] noted that the most of encrustations appear to be associated with the upper curl of the stent, requiring in some cases a percutaneous approach to release it.
The most frequently reported specific AEs were stent break (23%) and material problems (14%). In 2023, Bernasconi et al. [10] analyzed the difference of AEs rate per material, demonstrating a higher risk of encrustation, especially by calcium oxalate, for Polyurethane (PU) ureteral stents, while silicon has the lowest encrustation rate[14] and seems to be the best choice for stenting for stone disease after ureteroscopy[15].
Stent encrustation is an uncommon event with a significant impact in patients’ management[16]. Several scores are available to predict a complex surgery due to stent encrustation, i.e. the Forgotten Encrusted Calcificated (FECal) Score[17].
Metallic stents can resist high compression forces and are useful in long-term drainage[11]. Metals make stents ductile, malleable, easy-to-mold and resistant to compression. Scientific evidence suggests that these stents when compared to other double J stents provide less morbidity, a longer indwelling time, a greater patency rate and a better management of the strictures. However, they cause epithelial hyperplasia and ingrowth of this hyperplastic tissue, and stent exchange may be challenging[18].
Ureteral stent break is an extremely uncommon AE and it has been described only in an handful of case reports in literature. Analyzing these reports, we can see a higher risk of breakage when the indwelling period is extended, or when performing procedures like ESWL[19–22]. In such situations ureteral stents fragments can cause the obstruction of the kidney leading in some cases to the necessity to perform nephroureterectomy[22].
Differences in manufacturers are difficult to interpret since it is not possible to assess the real number of stents per manufacturer produced and placed. However, when reading the results, it is important to consider that MAUDE database is supplied by voluntary reports from healthcare providers, patients and consumers. In our analysis, most of the reports were associated with Resonance and Cook ureteral stents. This is not thought to be related to materials or shape of these manufacturers’ devices, but the most plausible hypothesis is that these stents represent the most used in urological practice, making them more likely to be subject to reporting.
Polymeric stents remain the leading choice in the ureteric stent market. Their relatively inert nature provides a reliable short-term option. Progress has been made through enhancements in polymer compositions and stent coatings[23]. Developments in biodegradable/bioresorbable stents and various stent coatings aim to tackle issues associated with stents, such as infection, pain, and encrustation. Yet, many of these new technologies are still in the preclinical stage and have shown limited effectiveness in clinical trials. Research and development in stent design are ongoing. The advancement of metallic stents has proven beneficial for patients with chronic ureteral constriction, especially in instances of malignant blockage. Future directions in ureteric stent research could involve the creation of smart stents equipped with monitoring and communication features. It is anticipated that ongoing design improvements and innovations will lead to reduced complications for all patients using ureteral stents.
There are several key limitations of the MAUDE database. Submissions may be incomplete, inaccurate, untimely, unverified, or biased. Since reporting is voluntary, there is a very high risk of underreporting; the incidence or prevalence of an event cannot be determined from these data alone. There is also restricted patient demographic and follow-up data and no information on surgeon experience and case volume.[24] Despite these limitations, the present study is the first to analyze a real-life scenario of stent related adverse events[25].