Two cases of emphysematous pyonephrosis are presented and discussed. Resulting from the extension of a renal infection into an obstructed collecting system, emphysematous pyonephrosis usually occurs in patients with diabetes mellitus, is usually unilateral, and generally has a poor clinical prognosis. Sonographically, emphysematous pyonephrosis presents as strong echoes near the renal sinus with acoustic shadowing and/or reverberation artifacts.
