- Emphysematous pyelonephritis represents a severe life-threatening infection (overall mortality rate of approximately 50%) of the renal parenchyma with gas-forming bacteria.
- Underlying poorly controlled diabetes mellitis is present in up to 90% of patients who develop emphysematous pyelonephritis.
- Patients present clinically with varying degrees of renal failure, lethargy, acid-base irregularities, and hyperglycemia.
- E coli is the causative bacterial source in approximately 70% of cases
 Imaging Findings
 Plain film
- Conventional radiography may demonstrate gas bubbles overlying the renal fossa or may show a diffusely mottled kidney with radially oriented gas corresponding to the renal pyramids.
- US will characteristically show an enlarged kidney containing high-amplitude echoes within the renal parenchyma, often with low-level posterior dirty acoustic shadowing; however, the depth of parenchymal involvement may be underestimated at US, and multiple renal stones may also manifest as echogenic foci without "clean" posterior shadowing.
- Additional evaluation with CT will confirm the presence and extent of parenchymal gas and will often allow identification of the source of obstruction when present.
- The use of intravenous contrast material will often reveal asymmetric renal enhancement or delayed excretion, and, during the nephrographic phase, will help identify areas of focal tissue necrosis or abscess formation.
 See Also
 External Links
- David E. Grayson, Robert M. Abbott, Angela D. Levy, and Paul M. Sherman. Emphysematous Infections of the Abdomen and Pelvis: A Pictorial Review. RadioGraphics 2002 22: 543-561.