Bilateral urinary calculi with discordant stone composition.

OBJECTIVES: To describe a cohort of bilateral stone formers with significantly different compositions between renal units. METHODS: Patients treated for bilateral nephrolithiasis over a 4-year period (2007-2010) were identified. Stones were categorized by dominant (≥50%) mineralogical component. Patients with significant compositional differences between renal units (discordant stone formers) were compared to patients with a similar stone type in each kidney. RESULTS: Fifteen of the 59 bilateral stone formers (25.4%) were discordant stone formers with significant differences in stone composition between renal units. Forty-four of the 59 patients (74.6%) had the same stone composition on each side. Thirty percent of discordant stones had calcium phosphate as the dominant stone component. Discordant stone formers were younger, had better renal function, and tended to have a larger stone burden (p < 0.05). CONCLUSIONS: A significant minority of bilateral stone formers form a different type of stone in each kidney. Local or micro-environmental etiologies may explain this phenomenon and may also account for failure of preventive therapy in some patients.

Metallic ureteral stents: a cost-effective method of managing benign upper tract obstruction.

INTRODUCTION: The management of patients with upper urinary tract obstruction who are not candidates for definitive reconstruction often presents a challenge. We report our initial experience with the Resonance (Cook Urological, Spencer, IN) metallic ureteral stent for the management of benign ureteral obstruction and present a comparative cost analysis of metallic to standard polymer stent use. METHODS: Data were retrospectively gathered on all patients undergoing metallic ureteral stent placement for benign causes from July 2007 to February 2009. Baseline demographics, previous method of drainage, pre- and postoperative creatinine levels, procedural complications, stent-related side effects, and metallic stent dwell time were recorded. The cost of stent maintenance for polymer and metallic stents for a 12-month interval was calculated for each patient. RESULTS: Fifteen stents were placed in 13 patients to manage obstruction due to a variety of benign etiologies. Metallic stents provided adequate drainage in 12/13 patients, but were discontinued prematurely in 3 patients (2 for voiding symptoms, 1 for hematuria). Eight patients had their metallic stents changed after a mean time of 11.6 months, with no encrustation. The yearly cost associated with polymer and metallic stent use was $23,999 and $11,183, respectively. This amounted to a $10,394 annual cost reduction (43%) for each patient. CONCLUSIONS: Metallic ureteral stents provide effective upper tract drainage for the majority of patients with benign upper tract obstruction, with significant cost benefit, largely because of the shorter exchange interval.

The FECal Double-J: a simplified approach in the management of encrusted and retained ureteral stents.

INTRODUCTION: The management of the forgotten, encrusted, calcified (FECal) Double-J ureteral stents can represent one of the most difficult and challenging surgical conditions for the practicing urologist. We present a novel and simple grading system for the FECal stent and, taking into account our own experience and literature review, propose an algorithm in the management of the encrusted stent based on this new system. MATERIALS AND METHODS: A retrospective analysis of our stone database was performed from March 2000 to April 2007 revealing a total of nine patients presented with a FECal Double-J stent managed at our institution and included in our series for further analysis. Based on this population, our experience, and current surgical techniques, we designed a simplified grading system to universally define the retained indwelling FECal ureteral stents. RESULTS: A total of nine patients with encrusted and retained ureteral stents were identified, graded, classified, and treated at our institution. Our population consisted of five women and four men with an average age of 54.4 years and average stent indwelling time of 11.44 months. We present our novel management algorithm based on our simplified FECal stent grading system. CONCLUSION: The management of the FECal ureteral stent represents a formidable challenge due to the need for a multimodal approach with advanced endourological techniques. Our proposed grading system and management algorithm provide a simplified and directed alternative for the surgical management dilemma of the encrusted retained ureteral stent.