Emphysematous pyelonephritis: The impact of urolithiasis on disease severity

Background: Emphysematous pyelonephritis is a severe infection of the kidney associated with formation of gas in the renal parenchyma and/or collecting system. The purpose of this study was to evaluate outcomes of patients with emphysematous pyelonephritis in a contemporary cohort and to evaluate the impact of urolithiasis on disease severity. Methods: A search of all imaging reports at University of California San Francisco (UCSF) for the term "emphysematous pyelonephritis" was undertaken from 2003-2014. Patients were included if there was clinical evidence of infection, no recent urologic instrumentation, and computerized tomography (CT) demonstrating gas in the renal parenchyma or collecting system. Clinical and laboratory variables were obtained from medical records. Results: A total of 14 cases were identified. The majority of patients (57%) had gas confined to the collecting system. Three patients (21%) had gas in the renal parenchyma and 3 patients (21%) had gas extending into perirenal tissues. A total of 8 patients (57%) had concomitant urolithiasis. Seven patients (50%) were managed with antibiotic therapy alone while 6 patients (43%) required percutaneous drainage. No patients required immediate nephrectomy. There were no deaths. Patients with urolithiasis had less severe emphysematous pyelonephritis than patients without urolithiasis (P < 0.05). Conclusions: The majority of patients in this study had gas contained within the collecting system and were treated successfully with antibiotics alone. Percutaneous drainage was successfully utilized in patients with more advanced disease. No patients required emergent nephrectomy. Emphysematous pyelonephritis in patients with urolithiasis was less severe than in patients without urolithiasis.