Ureteral stent encrustation. Pathophysiology

Ureteral stents are the most commonly used urological implants. They are used for temporary as well as for long-term ureteral stenting. Amongst others, complications of ureteral stenting are encrustation and cellular adherence which, in turn, promotes urinary tract infection and can induce impaired healing in case of ureteral damage. Biofilm formation on urological implants leads to the protection of persisting bacteria from local defense mechanisms, thereby rendering persistent urinary tract infections more common. It seems clear that antibiotics cannot penetrate into biofilms adequately. Also, bacteria persist in biofilms in a state of reduced metabolism which further reduces antibiotic efficacy. Furthermore, bacteria develop resistance more quickly in biofilms. This paper tries to give an overview of the complex pathophysiological mechanisms that underlie stent encrustation as far as we know to date.

Urologische Komplikationen nach Nierentransplantation

Between August 1981 and May 2005, 1065 consecutive kidney transplants were performed at our center; 393 patients (36.9%) developed urological complications in the first 60 postoperative days. Urinary tract infections occurred in 28.5% of all patients. The major urological problems seen were urinary leakage and ureteral obstruction in 6.2% and 1.4% of the patients. Two grafts were lost due to severe urinary leakage. No patient death occurred due to urological complications. The incidence of urological complications is mainly influenced by the surgical procedure of organ retrieval and ureteroneocystostomy. With double-J stenting of the extravesical ureteroneocystostomy, we observed a significantly lower rate of urinary leakage but a higher rate of urinary tract infections in our series. Early diagnosis and treatment of urological complications may prevent further morbidity of our transplant patients.