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Acute pyelonephritis

Last reviewed: 28 Oct 2023
Last updated: 27 May 2022



History and exam

Key diagnostic factors

  • fever
More key diagnostic factors

Other diagnostic factors

  • nausea and vomiting
  • dysuria, frequency, or urgency
  • flank pain or costovertebral angle tenderness
Other diagnostic factors

Risk factors

  • urinary tract infection
  • diabetes mellitus
  • stress incontinence
  • foreign body in urinary tract (e.g., calculus, catheter)
  • anatomic/functional urinary abnormality
  • immunosuppressive state (e.g., HIV, transplantation, chemotherapy, corticosteroid use)
  • pregnancy
  • frequent sexual intercourse
  • mother with urinary tract infection history
  • new sex partner
  • spermicide use
  • age between 18 and 50 years
  • age >60 years
More risk factors

Diagnostic investigations

1st investigations to order

  • urinalysis
  • Gram stain
  • urine culture
  • complete blood count
  • erythrocyte sedimentation rate
  • C-reactive protein
  • procalcitonin
  • blood culture
More 1st investigations to order

Investigations to consider

  • renal ultrasound
  • contrast-enhanced spiral computed tomography
  • magnetic resonance imaging
More investigations to consider

Emerging tests

  • interleukin
  • copeptin

Treatment algorithm


high index of suspicion with mild-to-moderate symptoms and uncomplicated disease

high index of suspicion with severe symptoms or complicated disease or pregnant patients


mild-to-moderate symptoms with uncomplicated disease

severe symptoms or complicated disease or pregnant patients


recurrent disease within 1 to 2 weeks



Lynda A. Frassetto, MD

Professor of Medicine

Division of Nephrology

University of California

San Francisco



LAF declares that she has no competing interests.


Dr Lynda A. Frassetto would like to gratefully acknowledge the assistance of Donna M. Frassetto. DMF declares that she has no competing interests.

Peer reviewers

John Lam, MD

Attending Urologist

Providence Saint Joseph Medical Center


Assistant Clinical Professor of Urology

Department of Urology

David Geffen School of Medicine at UCLA

Los Angeles



JL declares that he has no competing interests.

Robert Mactier, MD, FRCP

Consultant Nephrologist/Lead Clinician

Renal Unit

Glasgow Royal Infirmary

NHS Greater Glasgow and Clyde




RM declares that he has no competing interests.

  • Acute pyelonephritis images
  • Differentials

    • Chronic pyelonephritis
    • Pelvic inflammatory disease
    • Pelvic pain syndrome
    More Differentials
  • Guidelines

    • ACR appropriateness criteria: acute pyelonephritis
    • EAU guidelines on urological infections
    More Guidelines
  • Patient leaflets

    Kidney infection

    Kidney stones

    More Patient leaflets
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