Sonography of emphysematous pyelonephritis.

Emphysematous pyelonephritis is a rare gas-producing bacterial infection of the renal parenchyma seen primarily in patients with diabetes mellitus. Sonographic findings in four patients with this disease are described. Sonographic features consist of multiple high-amplitude echoes within the renal parenchyma, renal sinus, and/or perirenal space accompanied by acoustic shadowing. Computed tomography confirmed bilateral involvement in one case. Plain abdominal radiographs demonstrated abnormal extraluminal gas in three of four cases. The role of sonography in diagnosis is discussed.