Perinephric abscess


  • An abscess of the perinephric fat that abuts the renal cortex
  • Can arise as a complication either a pre-existing pyelonephritis (majority) or from hematogenous seeding

Causative Organisms[1]

  • E. coli (51.4%)
  • S. aureus (10%)

Perinephric vs renal abscess

Perinephric Renal
Necrotic AreaPerinephric fat between the renal cortex and Gerota's fasciaRenal parenchyma
CausePyelonephritis (majority)Pyelonephritis (vast majority)
Risk of morbidityHigherLower

Genitourinary infection

"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

  • Sign/symptoms similar to pyelo (fever, CVAT, dysuria)
  • Occurs in setting of ascending infection with obstructed pyelo

Differential Diagnosis



Laboratory Testing

  • CBC - Although it is a non-specific finding, a leukocytosis is typically seen.
  • Chemistry Panel - Lactic acidosis is a common finding and is seen earlier in the disease course in diabetic patients. Renal insufficiency is also commonly seen as well.
  • Urinalysis - Will often show evidence of pyelonephritis, however if the perinephric abscess is secondary to hematogenous spread, the urine could be sterile. Therefore a negative U/A does NOT rule out a perinephric abscess.
  • Blood and urine cultures


  • CT
    • Imaging modality of choice
    • Sensitivity ~90%.
  • Renal ultrasound - A fluid filled mass extending from the renal cortex into the perinephric fat can be seen.


  • Antibiotic therapy depends on the suspected cause
  • Abscess drainage
    • Abscess of ANY size requires IR for percutaneous drainage
    • If any urological obstruction is suspected (nephrolithiasis, ureterolithiasis, external compression from abdominal cavity, presence of pre-existing ureteral stent), emergent urological consultation should be obtained


  • Admission

See Also


  1. Liu XQ, et al. Renal and perinephric abscesses in West China Hospital: 10-year retrospective-descriptive study. World Journal of Nephrology. 2016 Jan;5(1):108-14.
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