Sonography of emphysematous pyelonephritis.

Abstract

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.

Pyelonephritis: Radiologic-Pathologic Review

“…When positive findings of pyelonephritis are found at US, they can include congenital anomalies and a variety of changes in the renal parenchyma such as hydronephrosis, renal enlargement, loss of renal sinus fat due to edema, changes in echogenicity due to both edema (hypoechoic) or hemorrhage (hyperechoic) (Fig 3) (15), loss of corticomedullary differentiation, abscess formation, and areas of hypoperfusion (visible with power Doppler interrogation). Even when positive US findings are observed, US is limited in the definitive differentiation of calcification from intraparenchymal or collecting system gas (manifested respectively as "clean" shadowing and "dirty" shadowing with echoes and reverberations), identification of perinephric extension of infection, and visualization of small microabscesses that are common in early acute infections (Fig 4) (16,17). Occasionally, areas of CT scan shows the enlarged kidney with global decreased uptake of contrast material and multiple small low-attenuation foci from abscess pockets, findings that prompted nephrectomy.…”

“…Nondiabetic patients are typically either immunocompromised or have associated urinary tract obstruction secondary to uroliths, neoplasm, or sloughed papilla. The most commonly identified organisms are E coli, Klebsiella pneumonia, and Proteus mirabilis (1,16). Without early therapeutic intervention, the condition becomes rapidly progressive, generalizes to fulminant sepsis, and carries a high mortality rate.…”

Emphysematous Pyelonephritis: Bedside Ultrasound Diagnosis in the Emergency Department

“…This should be differentiated from the posterior acoustic shadowing of intrarenal calculi, which have a distinctive echo-free shadow distal to the calculus. 15 If fluid collections are present, EPs may note ring-down artifact from air trapped within fluid collections. In severe cases in which there is a significant amount of air or perinephric fluid, the artifact may completely obscure the kidney and make visualization difficult or even impossible.…”

“…In severe cases in which there is a significant amount of air or perinephric fluid, the artifact may completely obscure the kidney and make visualization difficult or even impossible. 7 , 15 …”

“… 16 The overall mortality of EPN is estimated to be 25–42%. 10 , 15 One study reports a survival rate of 29% with antibiotics alone but a 71% survival rate if both antibiotics and surgical intervention are implemented. 10 Other studies report a mortality rate as high as 50–70% with antibiotics alone but improved mortality of 7–13.5% with antibiotics plus surgery or percutaneous drainage.…”