Login to Access Video or Poster Abstract: MP01-01
Sources of Funding: None

Introduction

Acute ureteral stent encrustation (USE) is a commonly encountered problem that can increase stent morbidity and make stone treatment challenging. Previous research into USE has focused on the physical and biochemical properties of ureteral stents to decrease encrustation. To date, this research has proven generally unsuccessful. To our knowledge, no detailed data exists on individual patient characteristics of early stent encrusters. We sought to characterize this population in order to identify risk factors associated with acute USE.

Methods

An IRB approved prospective study was designed to identify patients with early USE, defined as a calcified stent identified within 3 months of stent placement. From June 2016 to October 2016 all patients with indwelling ureteral stents were screened. Patients with stent encrustation were identified. Demographic data, past medical history, indwelling time of stent, stent size, and stent manufacturer were collected. Additionally, at the time stent removal, urine analysis, urine culture, stent culture, stone culture, encrusted stent stone analysis, and ureteral stone analysis were obtained.

Results

Seventy-six consecutive patients undergoing ureteroscopy and stent placement were screened. 9.2% of cases demonstrated early USE. Average age of our cohort was 46 years old (STD 5.1) and 57% of patients were female. Urinary tract stones were found in the ureter (60%) and renal pelvis (40%). Average BMI was 26.2 (STD 6.3). No patient had identifiable metabolic stone disease. All patients had normal baseline renal function (GFR>60). The median indwelling stent time was 56 days (IQR 44-69 days). 57% of patients had a positive urine culture taken at time of stent removal. In 71% of patients, the major stone composition for USE and urinary tract stones was brushite (range 60-100%). Stone and calcified stent cultures were positive in 4 of 7 patients, but were never the same organism isolated in urine culture. Only 1 patient had an encrusted stent consistent with struvite. Furthermore, Streptococcus species were isolated in 50% of encrusted stent cultures. One patient had a positive stent culture with a negative concomitant urine culture.

Conclusions

In our series, the most common calcification associated with acute USE was brushite stones. Additionally, stone and calcified stent cultures were positive with organisms dissimilar from those isolated in the urine. Stone and calcified stent cultures should be obtained in this group of patients, principally if stent exchange or additional procedures are required.

Funding

None