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IS THERE A SHIFT FROM INFECTIOUS STONES IN STAGHORN CALCULI?

Login to Access Video or Poster Abstract: MP01-13
Sources of Funding: None

Introduction

Historically staghorn calculi have been thought of as infectious stones, made up primarily of magnesium ammonium phosphate or (struvite) stones. The American Urological Association (AUA) guidelines for management of staghorn calculi continue to state calcium oxalate or calcium phosphate stones as unlikely causes of staghorn calculi. We reviewed our institutions incidence of infectious and metabolic composition in large staghorn calculi

Methods

Medical records were retrospectively reviewed for patients who underwent percutaneous nephrolithotomy (PCNL) for complete staghorn calculus from 2010 to 2015. Stone analysis and charts were reviewed for demographics, surgical complications, preoperative urine results and outcomes compared to stone type. Primary outcome of the study was to identify stone composition in infectious and non-infectious cases

Results

217 PCNLs were completed at our institution between 2010-2015 for stones >2cm. 72 patients (75 kidneys) had large staghorn calculus that met our size criteria. 3 of these were excluded. Overall 28 (39%) of patients were found to have infection stones, either struvite or carbonate. 44(61%) stones were composed of metabolic based stones without any infectious composition. The primary compositions in the metabolic stone group were calcium phosphate (52%), Uric Acid (18%), calcium oxalate (18%), and cystine (12%). In patients with purely metabolic stones, 65% of patients with primarily calcium phosphate hydroxyapatite had positive pre-op urine cultures, while only 12.5% of patients with primary calcium oxalate stones had positive pre-op urine cultures. Preoperative urine cultures revealed Proteus present (4.5% vs 46.4%) for non-infectious and infectious stones. E. Coli was present in preoperative urine cultures (15.9% vs 3.5%) for non-infectious and infectious stones. Proteus was the most common bacteria in infectious stones, while E. Coli was most common with metabolic stones. Infectious stones were 3.2 times as likely to have at least a Clavien-Dindo Grade 1 complication as metabolic stones (p=0.017).

Conclusions

In our study more staghorn calculus were composed of metabolic stones than infectious stones. Calcium phosphate was the most common stone composition for staghorn calculi differing from historical reports of staghorn calculi being primarily infectious. Patients with calcium phosphate stones also had a high rate of positive urine cultures. More research is needed on the cause of this paradigm shift._x000D_ _x000D_

Funding

None

Authors
Tyler Haden
Paige Kuhlmann
Jacqueline Ross
Stephen Kalkhoff
Carrie Johans
Alex Jones
Stephen Weinstein
Mark Wakefield
Daniel Hoyt
James Cummings
Naveen Pokala
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