• We hope to use the urine metabolic data to clarify whether this subset of stone forming patients have significant underlying metabolic risk factors that contribute to stone formation within their diverticula. [ Time Frame: Two months post-op ] [ Designated as safety issue: No ]
  

Caliceal diverticula are non-secretory cavities which are connected to the remainder of the renal collecting system through narrow infundibulae. Calculi are associated with these cavities from 9.5 to 78% of cases (Liatsikos, et al 2000; Monga, et al 2000). This subset of stone-forming patients often presents with recurrent urinary tract infections and flank discomfort. The definitive treatment for this entity remains surgical, with shock wave lithotripsy (SWL), ureteroscopy (URS), percutaneous nephrolithotomy (PNL), and laparoscopy all serving as management options. However, multiple groups have demonstrated that PNL remains the treatment modality of choice secondary to its superior stone-free and symptom relief rates (Jones, et al 1991; Donnellan, et al 1999; Shalhav, et al 1998). Over time, technique modifications have been reported by other groups (Monga, et al 2000; Auge, et al 2002) involving different methods of managing the infundibulum that connects the diverticulum to the rest of the renal collecting system. Our own surgical experience with percutaneous treatment of stone-bearing caliceal diverticula has resulted in various technique modifications as well, which we believe have continued to improve patient outcomes. To support our hypothesis, we will need to perform a systematic review our patient population to document these surgical outcomes.

Another question surrounding this subset of patients involves the primary factor responsible for the formation of calculi within the diverticula. Unfortunately, the literature has provided conflicting data on this issue. Some groups attribute stone formation to underlying metabolic abnormalities (Hsu, et al 1998). Other groups have not found any metabolic problems, instead concluding that impaired urinary drainage from the diverticulum primarily contributes calculus formation (Liatsikos, et al 2000). By prospectively obtaining urines on our caliceal diverticula patients, we hope that detailed metabolic analyses will allow us to conclude definitively whether metabolic abnormalities are prevalent in this population.