emphysematous pyelitis

Emphysematous pyelitis is isolated gas production inside the excretory system, secondary to acute bacterial infection. It is a relatively benign entity and needs accurate differentiation from the far more serious emphysematous pyelonephritis, which is gas production from an infection in the renal parenchyma rather than just in the collecting system.


Emphysematous pyelitis is more common in females . Risk factors include diabetes mellitus and urinary tract obstruction.

Clinical presentation

Symptoms are usually mild, with fever and chills. Sometimes flank tenderness with dysuria is present.



E. coli, Klebsiella, Aerobacter aerogenes, and Proteus mirabilis are the commonest causative organisms.

Radiographic features

Plain radiograph

Retroperitoneal gas is seen in many patients. Associated urolithiasis, if any, may also be seen.


Gas within the pelvicalyceal system may be evident as dirty shadowing on ultrasound.


Gas-fluid level in dilated calyx, usually with mild or no obvious features of pyelonephritis.

Treatment and prognosis

Emphysematous pyelitis generally carries a good prognosis and usually responds to intravenous antibiotics followed by oral antibiotics .

Differential diagnosis

General considerations include:

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