An obese 55-year-old woman had intermittent dysuria and frequent urination for 4 days and fever, abdominal pain, and vomiting for 3 days. Her history included type 1 diabetes mellitus, hypertension, and angina; her medications included insulin, nifedipine, and nitroglycerin. Dr Virendra Parikh of Fort Wayne, Ind, noted tenderness in the right upper quadrant, the suprapubic area, and the right flank. The patient's temperature was 39.4°C (103°F); blood glucose level, 304 mg/dL; white blood cell (WBC) count, 23,400/µL; serum blood urea nitrogen, 54 mg/dL; creatinine, 2.5 mg/dL; and urine pH, 5. The urine culture was positive for Escherichia coli and Klebsiella species; a blood culture was positive for E coli. The patient was admitted to the ICU. Plain abdominal films showed no abnormalities. An abdominal CT scan at the level of the middle third of the right kidney demonstrated gas within the collecting system (A, arrow). A slightly more inferior image showed the ureter dilated with gas and containing debris (B, arrow). The patient had received intravenous ampicillin and gentamicin in the ICU. Based on the results of urine and blood cultures, these drugs were discontinued and a broad-spectrum antibiotic, imipenem and cilastatin sodium, was substituted. Insulin was given to control the patient's diabetes. During the next 5 days, she became afebrile and her WBC count normalized. A second CT scan showed no evidence of abscess and revealed marked resolution of gas in the collecting system. An intravenous pyelogram obtained during follow-up showed no obstruction. Renal emphysema, or gas in the urinary tract, comprises 2 distinct entities that each require specific management and have a different prognosis.
- Emphysematous pyelitis is an extremely rare condition in which gas is localized to the collecting system of the kidney. The disorder usually occurs with urinary tract obstruction. Up to 50% of patients with this condition have diabetes mellitus. E coli is the most common infectious cause; other culprit organisms include Klebsiella, Proteus, Citrobacter, Aerobacter, and Candida species. It has been postulated that the high glucose concentration in the tissues provides the substrate for organisms that can produce carbon dioxide and hydrogen by fermentation of sugar.
- Emphysematous pyelonephritis is the presence of gas within the renal parenchyma. Nephrectomy usually is required for patients with this disorder whose condition continues to deteriorate despite broad-spectrum antibiotic therapy. This disease is more serious than emphysematous pyelitis; mortality rates of at least 60% have been reported. In contrast, mortality among patients with emphysematous pyelitis is approximately 19%.1
When gas is localized in the collecting system and urine flow is unobstructed, antibiotics appear to be sufficient therapy. Coexisting obstruction to urine flow requires correction because it can limit the response to antibiotics.
1.Wan YL, Lo SK, Bullard MJ, et al. Predictors of outcome in emphysematous pyelonephritis. J Urol. 1998;159:363-373.