Introduction: Ureteral obstructions are managed by complex surgery not always feasible for surgical field complexity or poor patient conditions. Various surgical maneuvers, as ureteral dilation, stenting and percutaneous nephrostomy, can be offered, but they are related to considerable failure rates and negative impact on quality of life. In selected cases, the positioning of long-term expandable metallic ureteral stents (EMUSs) may be an appropriate and successful choice.
Evidence acquisition: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria, a systematic review of the literature was performed in July 2017 using PubMed, Cochrane Library, Scopus and Web of Science databases. The search was conducted by typing the following terms: "Expandable metallic ureteral stent," "Memokath ureteral stent," "Allium ureteral stent," and "Uventa ureteral stent."
Evidence synthesis: Twenty studies reported the safety, efficacy and clinical outcomes related to the common available EMUSs. Most studies were single-arm, retrospective and involving a low number of clinical cases, resulting in significant difficulties with outlining indications and drawing conclusions. Available papers showed EMUSs offered a high rate of patency, a long duration and a good quality of life, even if they are associated with significant complications.
Conclusions: Since the first description of ureteral stents 50 years ago, we have faced a significant evolution in stent design. The current generation of EMUSs offers many advantages, but the onset of adverse effects is still significant and limits their use to selected cases. Further research should be addressed to the realization of prospective, multi-institutional randomized clinical trials to highlight indications to manage appropriately ureteral obstructions.