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Emphysematous pyelonephritis - Review

Emphysematous pyelonephritis is an acute necrotizing infection characterized by gas formation.
It is characterized by the presence of gas in and around the kidney.

E. coli (58%) and K. pneumoniae (21%) are the organisms most commonly isolated. Clostridium and Enterobacter spp may also be responsible, 7% each.

1) Diabetes mellitus (70-90%)- usually patients with poor glucose control. High levels of glucose in the urine serve as a substrate for these bacteria and large amounts of gas are generated through natural fermentation
2) Obstruction (25-40%)- it is another common predisposing factor for emphysematous pyelonephritis.

For non-diabetics, protein fermentation is a proposed source of gas formation.

7% of cases may be asymptomatic.
If symptomatic, patients may complain of pneumaturia, irritative lower tract voiding symptoms, flank pain or may present in a severe septic condition with an acute abdomen and high grade fever.

1) Plain radiograph of the abdomen can help us in 80-85 % of cases.
2) CT is considered the optimal imaging technique for confirming emphysematous infection and characterizing the extent of involvement.

According to radiological findings and CT scans, emphysematous pyelonephritis can be classified as follows:
Class 1— gas confined to the collecting system
Class 2— gas confined to the renal parenchyma alone
Class 3A— perinephric extension of gas or abscess
Class 3B— extension of gas beyond the Gerota fascia
Class 4— bilateral EPN or EPN in a solitary kidney
Emphysematous pyelonephritis

 Plain abdominal radiograph showing presence of air around the left kidney

Emphysematous pyelonephritis
 CT scan showing left emphysematous pyelonephritis with presence of gas and parenchymal destruction
Emphysematous pyelonephritis
CT scan of a diabetic patient with emphysematous pyelonephritis due to uncontrolled diabetes and renal stones.

1) Medical management includes antimicrobial therapy, bladder drainage and glycemic control.   effective.
2) Surgical intervention usually is required for only 10% of the cases. Emergency nephrectomy was traditionally considered necessary but currently, percutaneous drainage is the recommended initial approach.

 Later, elective nephrectomy may be required for some patients.

First published on: 15 April 2017


  1. Recently we came across a case of emphysematous PN - she came with flank pain and fever with rigors - - had uncontrolled DM - USG kidneys showed air around the kidney. CT KUB cnfirmed it - She was treated with IV meropenem and recovered. The post is useful and we may really come across such a pt in our pratice.


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