Renal abscess


  • Rare clinical entity which can lead to delayed diagnosis
  • Usually a complication of a UTI or pyelonephritis
  • Less often can be due to hematogenous spread from other sources of infection
    • Most commonly due to Staph aureus

Risk Factors

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

  • Costovertebral, flank, lumbar, lower chest, or back pain
    • Usually unilateral
  • Fever, especially if prolonged or after antibiotic initiation
  • Nausea, vomiting
  • UTI or pyelonephritis symptoms not improving with antibiotics


Differential Diagnosis



  • Labs
    • CBC, BMP, UA, lactate
    • Urine culture, blood cultures
      • Some studies have shown up to 66% will have + blood cultures
  • Imaging
    • Renal ultrasound
      • Well-defined hypoechoic lesion with thick walls and usually with internal debris
    • CT


  • Antibiotics
    • Broad spectrum if unclear source
      • If urinary source cover typical urinary pathogens
      • If hematogenous spread considered, cover for MSSA and MRSA
  • Percutaneous drainage
  • Open surgical management if patient fails antibiotics/percutaneous drainage


  • Admission for IV antibiotics and drainage
    • Especially if elderly or elevated BUN or creatinine


  • Dembry LM, Andriole VT. “Renal and Perirenal Abscesses” Infectious Disease Clinics North America: 11, 3, (Sept 1997).
  • Getting GK, Shaikh N. “Renal Abscess” Journal of EM: 31, 1 (2006): 99-100.
  • Judith E, Stapczynski J. Stephan. "Urinary Tract Infections” Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York: McGraw-Hill, 2011. 632.
  • Yen DHT, et al. “Renal Abscess: Early Diagnosis and Treatment” Am J EM: 17, 2 (March 1999).
  • Shu T, Green JM, Orihuela E. “Renal and Perirenal Abscesses in Patients with Otherwise Anatomically Normal Urinary Tracts” Journal of Urology: 172 (July 2004): 148-150.
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