Urinary stents (ureteral-urethral, polymeric-metallic), are routinely used. They have many indications, but their main function is to facilitate urine drainage, as internal scaffolds, in cases of urinary obstruction caused by lithiasis, cancer, benign disease, surgery, kidney transplant, etc. However, despite their great usefulness, urinary stents are associated to numerous side effects and complications that reduce their efficacy. This leads to a significant impairment in the patient’s quality of life and to an increase in health expenditure. Sometimes, these adverse effects and complications become intolerable and lead to early stent removal. Regarding metallic stents, their use is not meaningful compared to vascular, biliary and digestive stents. The aim of this Action is twofold. Firstly, to create a multidisciplinary group to identify the inherent problems in urinary stents related to: design, composition, biomaterials, coatings, encrustation, urinary tract-stent interaction, fluid dynamics and physiologic effects on the urinary tract. It is intended to assess the topic from different points of view, as the main problem responsible for stent-related morbidity is the lack of knowledge exchange between the clinical community and the bioengineering community. The second objective is to improve urinary stents. ENIUS Action members belong to different fields of study of stents; urologists, translational researchers, bioengineers, industrial partners, Scientific and patients Associations. The purpose is to create synergies for the progress on: the applications of new biodegradable stent materials, coatings, Nano-technology, In silico studies, metal stents, drug-eluting stents and bio-covered stents for their future use in urinary stent designs. Regarding stent improvement, it is intended to create a computational model simulation that will allow the assessment of new stent designs. To do so, meetings are proposed in this Action to share knowledge, as well as Training Schools, exchanges (STSMs), the creation of guidelines concerning the topic of the Action, Handbooks and Scientific Papers. To achieve these aims, a network will be established with different groups working on each of the aspects that can contribute to the improvement of urinary stents. Hence a scientific and technological progress will be accomplished that will allow the reduction of stent morbidity and therefore the increase of their success rate, which has a direct impact in patients’ health and welfare.


Among the urinary tract conditions that require stenting, the ones that stand out for their importance are urothelial carcinomas, urinary stones and renal transplants. Urothelial carcinomas are the fourth most common tumors in the world. They can be located in the lower (bladder and urethra) or upper (pyelocaliceal or ureter) urinary tract. Bladder tumors account for 90% of urothelial carcinomas and are the most common malignancy of the urinary tract. At any time, 2.7 million people have a history of urinary bladder cancer. Urinary stone incidence depends on geographical, dietary and genetic factors. Accordingly, the prevalence rates for urinary stones vary from 1-20%. In countries with a high standard of life such as Sweden, lithiasis prevalence is notably high (>10%). The Spanish prevalence was 5.7% in 2007 and 4.7% in Germany. For some areas an increase of more than 37% over the last 20 years has been reported. Also, stenting is mandatory after a renal transplant. In 2014, 19670 were performed in the EU.

The development of symptoms is one of the main side effects related to stents, causing a strong negative impact on patients' quality of life and possibly leading to early stent removal. Furthermore, 78% of patients state that pain affects their daily activities. Even efficiency at work decreases in 58%, and it may provoke sexual dysfunction in 32% of subjects. The main causes of these side effects are associated to the design and the materials with which the stent is manufactured. Researchers must take into account that urine represents a hostile environment for biomaterials, becoming very likely to cause urinary infection and encrustation. Consequently, thanks to new biodegradable biomaterials, nanomaterials, antibacterial coatings and to the implementation of computational design, it is very predictable that urinary stent pitfalls and side effects will be reduce, having a substantial patient´s benefit. One of the reasons that prevent the improvement of designs and the implementation of new biomaterials-nanomaterials is the scattering of the groups at European level, the limited size of those groups and the absence of interaction between them. This is a circumstance that this Action is intended to solve by creating a multidisciplinary group. Nowadays, the opportunity to improve stents is very evident, with leading groups at worldwide level in stent design, biomaterials and nanomaterials assessment, urologist, regenerative medicine for medical biotechnology, bioengineers from different fields (computational, nano-technology, chemical, fluid dynamics, etc.) and medical devices' industries applied to medical engineering.

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