Emphysematous pyelonephritis


Renal anatomy.
  • Rare gas-forming infection nearly always occurring in patients with DM and obstruction
    • Patients appear toxic and septic; nephrectomy may be required

Genitourinary infection

(1) Human urinary system: (2) kidney; (3) renal pelvis; (4) ureter; (5) urinary bladder (6) urethra.
Additional structures: (7) adrenal gland; (8) renal artery and vein; (9) inferior vena cava; (10) abdominal aorta; (11) common iliac artery and vein; (12) liver; (13) large intestine; (14) pelvis.

"UTI" frequently refers specifically to acute cystitis, but may also be used as a general term for all urinary infections; use location-specific diagnosis.

Clinical Features[1]

Differential Diagnosis



Axial CT scan image of left kidney reveals emphysematous pyelonephritis.



  • CT is definitive
  • Staging[2]:
    • Class 1 - gas confined to collecting system
    • Class 2 - gas confined to renal parenchyma alone
    • Class 3A - perinephric extension of gas or abscess
    • Class 3B - extension of gas beyond Gerota fascia
    • Class 4 - bilateral or EPN in solitary kidney



  • Poor prognostic risk factors:
    • Creatinine > 1.4mg/dL
    • Platelets < 60k
    • Altered mental status
    • Shock
  • Urological consult for percutaneous drainage, stent placement, or nephrectomy (classes 3 and 4 with 2 or more prognostic risk factors)
  • Presence of obstructive stone requires even more urgent surgical intervention
  • Mortality rates between ~20-40%

See Also

External Links


  1. Tang HJ, et al. Clinical characteristics of emphysematous pyelonephritis. J Microbiol Immunol Infect. 2001 Jun. 34(2):125-30.
  2. Huang JJ, Tseng CC. Emphysematous pyelonephritis: clinicoradiological classification, management, prognosis, and pathogenesis. Arch Intern Med. 2000 Mar 27. 160(6):797-805.
  3. Shetty S et al. Emphysematous Pyelonephritis Treatment & Management. eMedicine. Apr 11, 2014. http://emedicine.medscape.com/article/457306-treatment#showall.