Perinephric abscess

Background

  • 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]

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

Clinical Features

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

Differential Diagnosis

Dysuria

Evaluation

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

Imaging

  • 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.

Management

  • 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

Disposition

  • Admission

See Also

References

  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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