Wednesday Image Review

What’s the Diagnosis? By Dr. Daniel Petrosky

A 44 year old woman with a past medical history of kidney stones and diabetes presents to the ED with 3 days of intermittent flank pain for which Tylenol is not helping. On exam, she is crying and in pain with some tenderness in RLQ and suprapubic area. No CVA tenderness noted. She denies fever and dysuria. A CT abdomen and pelvis with IV contrast was obtained and shown below. What’s the diagnosis?

Answer: bilateral emphysematous pyelonephritis (Findings: bilateral xanthogranulomatous pyelonephritis. Right perinephric stranding. Gas within both renal collecting systems and urinary bladder.)

This is a severe necrotizing infection of the kidney parenchyma. Primarily, cases occur in those with uncontrolled diabetes (95%) and a secondary factor is kidney obstruction (25-40%). The usual bacteria involved is E. Coli (69%) or K. Pneumoniae (29%). If caught early medical management of kidney function and antibiotics is the primary mode of treatment. Failure of initial treatment can lead to a nephrectomy.

  • Class 1: gas in the collecting system only
  • Class 2: gas in the renal parenchyma without extension to extrarenal space
  • Class 3A: extension of gas or abscess to perinephric space
  • Class 3B: extension of gas or abscess to pararenal space
  • Class 4: bilateral EPN or solitary kidney with EPN

Management: admit for IV antibiotics and urological consult

This particular case has Proteus as the infective species as evident by staghorn calculi and urine culture. Because of preserved kidney function (Cr 0.87) and WBC (4.45), Urology elected to monitor and treat infection first and schedule outpatient procedure for stone removal to prevent urosepsis.


Huang JJ, Tseng CC. Emphysematous pyelonephritis: clinicoradiological classification, management, prognosis, and pathogenesis. Arch Intern Med. 2000 Mar 27;160(6):797-805. doi: 10.1001/archinte.160.6.797. PMID: 10737279.

Ubee SS, McGlynn L, Fordham M. Emphysematous pyelonephritis. BJU Int. 2011 May;107(9):1474-8. doi: 10.1111/j.1464-410X.2010.09660.x. Epub 2010 Sep 14. PMID: 20840327.

Leave a Reply

Your email address will not be published. Required fields are marked *