Acute pyelonephritis


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Acute pyelonephritis


Renal and ureteral disorders

Renal agenesis

Horseshoe kidney

Potter sequence











Renal tubular acidosis

Minimal change disease

Diabetic nephropathy

Focal segmental glomerulosclerosis (NORD)


Membranous nephropathy

Lupus nephritis

Membranoproliferative glomerulonephritis

Poststreptococcal glomerulonephritis

Goodpasture syndrome

Rapidly progressive glomerulonephritis

IgA nephropathy (NORD)

Lupus nephritis

Alport syndrome

Kidney stones


Acute pyelonephritis

Chronic pyelonephritis

Prerenal azotemia

Renal azotemia

Acute tubular necrosis

Postrenal azotemia

Renal papillary necrosis

Renal cortical necrosis

Chronic kidney disease

Polycystic kidney disease

Multicystic dysplastic kidney

Medullary cystic kidney disease

Medullary sponge kidney

Renal artery stenosis

Renal cell carcinoma


Nephroblastoma (Wilms tumor)

WAGR syndrome

Beckwith-Wiedemann syndrome

Bladder and urethral disorders

Posterior urethral valves

Hypospadias and epispadias

Vesicoureteral reflux

Bladder exstrophy

Urinary incontinence

Neurogenic bladder

Lower urinary tract infection

Transitional cell carcinoma

Non-urothelial bladder cancers

Renal system pathology review

Congenital renal disorders: Pathology review

Renal tubular defects: Pathology review

Renal tubular acidosis: Pathology review

Acid-base disturbances: Pathology review

Electrolyte disturbances: Pathology review

Renal failure: Pathology review

Nephrotic syndromes: Pathology review

Nephritic syndromes: Pathology review

Urinary incontinence: Pathology review

Urinary tract infections: Pathology review

Kidney stones: Pathology review

Renal and urinary tract masses: Pathology review


Acute pyelonephritis


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USMLE® Step 1 questions

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Acute pyelonephritis

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USMLE® Step 1 style questions USMLE

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A 67-year-old woman is currently postoperative day 5 after having an open cholecystectomy. She reports worsening subprapubic pain and malaise.  Her vital signs are 37 °C (98.6°F), pulse is 98/min, respirations are 14/min, blood pressure is 137/64 mmHg, and oxygen saturation is 99% on room air. Physical examination shows suprapubic tenderness on palpation as well as cloudy urine in her Foley catheter. Which of the following pathogens is most likely causative of this patient’s clinical presentation?  

External References

First Aid








Acute pyelonephritis p. 625

labs/findings p. 723

renal papillary necrosis and p. 625

WBC casts in p. 618

Chronic pyelonephritis p. 625

labs/findings p. 723

Diabetes mellitus p. 352-360

pyelonephritis and p. 625

Pregnancy p. 657

pyelonephritis p. 625

Proteus spp.

xanthogranulomatous pyelonephritis p. 625

Pyelonephritis p. 625

kidney stones p. 628

labs/findings p. 723

urinary tract infections p. 179

WBC casts in p. 618

Renal papillary necrosis p. 625

pyelonephritis and p. 625

Urinary tract infections (UTIs) p. 179, 625

pyelonephritis p. 625

Urosepsis p. 625

Vesicoureteral reflux p. 603

pyelonephritis p. 625

Xanthogranulomatous pyelonephritis p. 625


Content Reviewers

Rishi Desai, MD, MPH


Tanner Marshall, MS

With acute pyelonephritis, pyelo- means pelvis, and -neph- refers to the kidney, so in this case it’s the renal pelvis, which is the funnel-like structure of the kidney that drains urine into the ureter, and -itis means inflammation. So acute pyelonephritis describes an inflamed kidney that develops relatively quickly, usually as a result of a bacterial infection.

Now a urinary tract infection, or UTI, is any infection of the urinary tract, which includes the upper portion of the tract—the kidneys and the ureters, and the lower portion of the tract—the bladder and urethra. So acute pyelonephritis is a type of upper urinary tract infection.

Acute pyelonephritis is most often caused by ascending infection, meaning bacteria start by colonizing the urethra and bladder, which would be a lower urinary tract infections, and make their way up the ureters and kidney, therefore upper UTI shares a lot of the same risk factors as lower UTI, things like female sex, sexual intercourse, indwelling catheters, diabetes mellitus, and urinary tract obstruction.

One major factor that increases the risk of an upper UTI from a lower UTI spreading upward is vesicoureteral reflux, or VUR, which is where urine is allowed to move backward up the urinary tract, which can happen if the vesicoureteral orifice fails. The vesicoureteral orifice is the one-way valve that allows urine to flow from each ureter into the bladder, but not in the reverse direction.


Acute pyelonephritis is a sudden, severe infection of the kidney. The infection may be caused by bacteria that travel up from the bladder or bacteria circulating in the blood (bacteremia). Symptoms of acute pyelonephritis can include fever, chills, nausea, vomiting, and pain in the lower back and sides. If left untreated, acute pyelonephritis can lead to serious complications like sepsis (a potentially life-threatening condition caused by infection).


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  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women: A 2010 Update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases" Clinical Infectious Diseases (2011)
  6. "Renal ultrasound and DMSA screening for high-grade vesicoureteral reflux" Pediatrics International (2016)
  7. "EAU Guidelines on Vesicoureteral Reflux in Children" European Urology (2012)
  8. "International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women: A 2010 Update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases" Clinical Infectious Diseases (2011)

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