Acute pyelonephritis

Last reviewed: 8 Jul 2022
Last updated: 20 Jul 2022



History and exam

Key diagnostic factors

  • flank pain
  • costovertebral angle tenderness
  • fever
  • new or different myalgia, or flu-like symptoms
  • presence of risk factors
  • nausea
  • vomiting
Full details

Other diagnostic factors

  • suprapubic tenderness
  • tachycardia
  • hypotension
Full details

Risk factors

  • urinary tract infection
  • diabetes mellitus
  • stress incontinence
  • foreign body in urinary tract (e.g., calculus, catheter)
  • anatomical/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
Full details

Diagnostic investigations

1st investigations to order

  • urinalysis
  • urine culture and sensitivity
  • full blood count
  • erythrocyte sedimentation rate
  • C-reactive protein
  • urea and electrolytes
  • creatinine
  • blood culture (in hospital)
Full details

Investigations to consider

  • renal ultrasound
  • contrast-enhanced CT
  • MRI
Full details

Treatment algorithm


uncomplicated: non-pregnant

complicated: non-pregnant



Expert advisers

Andrew Lewington, BSc (Hons), MBBS, MEd, MD, FRCP

Consultant Renal Physician

Honorary Associate Professor

Nephrology Department

Leeds Teaching Hospitals NHS Trust




AL is Associate Clinical Director of NIHR Leeds In-Vitro Diagnostics Co-operative, Co-Chair of UK Kidney Research Consortium Renal Clinical Study Group, Member of Kidney Research UK Research Grant Committee, Committee Member of NICE Kidney Injury Clinical Guideline Update 2018-20, Committee Member of NICE Diagnostic Assessment for Point of Care Creatinine Testing 2018-19. AL attended the Acute Dialysis Quality Initiative Meeting in San Diego 2018 (accommodation expenses); AL was a speaker at the AKI & CRRT Conference in San Diego 2019 (travel and accommodation expenses), the AKI Conference in Coventry 2019 (travel expenses), and the NIHR AKI and Sepsis Meeting in Leeds 2019 (no expenses).


BMJ Best Practice would like to gratefully acknowledge the previous expert contributor, whose work has been retained in parts of the content:

Lynda A. Frassetto, MD

Professor of Medicine

Division of Nephrology

University of California

San Francisco


LAF declares that she has no competing interests.

Peer reviewers

Shruti Goel, MBBS, FRCP

Consultant Nephrologist

The Hillingdon Hospital NHS Foundation Trust




SG declares that she has no competing interests.


Tessa Davis,

Section Editor, BMJ Best Practice

Consultant in Paediatric Emergency Medicine

Royal London Hospital




TD declares that she has no competing interests.

Emma Quigley,

Section Editor, BMJ Best Practice


EQ declares that she has no competing interests.

Susan Mayor,

Lead Section Editor, BMJ Best Practice


SM works as a freelance medical journalist and editor, video editorial director and presenter, and communications trainer. In this capacity, she has been paid, and continues to be paid, by a wide range of organisations for providing these skills on a professional basis. These include: NHS organisations, including the National Institute for Health and Care Excellence, NHS Choices, NHS Kidney Care, and others; publishers and medical education companies, including the BMJ Group, the Lancet group, Medscape, and others; professional organisations, including the British Thoracic Oncology Group, the European Society for Medical Oncology, the National Confidential Enquiry into Patient Outcome and Death, and others; charities and patients’ organisations, including the Roy Castle Lung Cancer Foundation and others; pharmaceutical companies, including Bayer, Boehringer Ingelheim, Novartis, and others; and communications agencies, including Publicis, Red Healthcare and others. She has no stock options or shares in any pharmaceutical or healthcare companies; however, she invests in a personal pension, which may invest in these types of companies. She is managing director of Susan Mayor Limited, the company name under which she provides medical writing and communications services.

Rachel Wheeler,

Lead Section Editor, BMJ Best Practice


RW declares that she has no competing interests.

Annabel Sidwell,

Comorbidities Editor, BMJ Best Practice


AS declares that she has no competing interests.

Adam Mitchell,

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

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