Emphysematous Pyelonephritis

Emphysematous pyelonephritis (EP) is a life threatening condition with a high overall mortality rate. About 90% of patients presenting with EP have uncontrolled diabetes mellitus. Urinary collecting system obstruction may also be present. E coli is the most common infecting organism. 

Typical US findings are shown above: the renal parenchyma appears echogenic with "dirty" shadowing. CT can confirm the presence of gas.

There is classification of EP into two types based on its CT appearance. Type 1 is characterized by diffuse replacement of the renal parenchyma with gas, without presence of discrete fluid collections. Type 2 EP demonstrates scattered foci of gas with associated regions of fluid attenuation. Type 1 EP carries a worse prognosis and is a surgical emergency.


REFERENCES
Craig WD, Wagner BJ, and Travis MD. Pyelonephritis: radiologic-pathologic review. Radiographics 2008;28:255-76.
Grayson DE, Abbott RM, Levy AD, et al. Emphysematous infections of the abdomen and pelvis: a pictorial review. Radiographics 2002;22:543-61.