Renal anatomy.


  • UTI = significant bacteriuria in presence of symptoms

Genitourinary infection

(1) Human urinary system: (2) kidney; (3) renal pelvis; (4) ureter; (5) urinary bladder (6) urethra.
Additional structures: (7) adrenal gland; (8) renal artery and vein; (9) inferior vena cava; (10) abdominal aorta; (11) common iliac artery and vein; (12) liver; (13) large intestine; (14) pelvis.

"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

Diagram showing the typical location of pain[1]
  • Pyelo = Cystitis symptoms AND fever/chills/nausea/vomiting
    • CVAT alone may be referred pain from cystitis
    • CVAT is only physical examination finding that increases likelihood of a UTI


  • Acute bacterial nephritis
    • CT shows ill-defined focal areas of decreased density
  • Renal/Perinephric abscesses
    • Sign/symptoms similar to pyelo (fever, CVAT, dysuria)
    • Occurs in setting of ascending infection with obstructed pyelo
    • Associated with DM and Renal Stones
    • Also occurs due to bacteremia with hematogenous seeding (Staph)
  • Emphysematous pyelonephritis
    • Rare gas-forming infection nearly always occurring in patients with DM and obstruction
      • Patients appear toxic and septic; nephrectomy may be required

Differential Diagnosis


Flank Pain



Urine with pyuria.
Renal ultrasound showing acute pyelonephritis with increased cortical echogenicity and blurred delineation of the upper pole.[2]


Blood cultures are NOT indicated (organisms in blood culture matched those in urine culture 97% of time)




Treatment is targeted at E. coli, Enterococcus, Klebsiella, Proteus mirabilis, S. saprophyticus


Consider one dose of Ceftriaxone 1g IV or Gentamycin 7mg/kg IV if the regional susceptibility of TMP/SMX or Fluoroquinolones is <80%

Adult Inpatient Options

Pediatric Inpatient Options


  • Discharge
    • Consider if young, otherwise healthy, tolerating PO
  • Consider admission if:[7]
    • Elderly (>60)
    • Renal Calculi
    • Obstruction
    • Recent hospitalization/instrumentation
    • DM
    • Immunocompromised
    • Unable to tolerate PO
    • Pregnancy
    • Solitary kidney or other anatomic abnormality


  • Admit all second trimester pregnant patients with OBGYN consult
  • Urology consult during the inpatient admission for pediatric patients due to the risk for urologic scarring
  • Consider advanced imaging to rule out abscess of urolithiasis if patient has failed 3 days of therapy

Special Populations


  • Elderly patients with pyelonephritis: 20% present with primary respiratory or GI symptoms. Also 33% are afebrile.[8]

See Also


  1. Urinary Tract Infection Common Clinical and Laboratory Features of Acute Pyelonephritis". Retrieved 14 July 2019.
  2. Content initially copied from: Hansen, Kristoffer; Nielsen, Michael; Ewertsen, Caroline (2015). "Ultrasonography of the Kidney: A Pictorial Review". Diagnostics. 6 (1): 2. doi:10.3390/diagnostics6010002. ISSN 2075-4418. PMC 4808817. PMID 26838799. (CC-BY 4.0)
  3. Gupta K, Hooton TM, Naber KG, et al. International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women. Clinical Infectious Diseases. 2011;52(5):e103-e120. doi:10.1093/cid/ciq257
  4. Colgan R, Williams M. Diagnosis and treatment of acute uncomplicated cystitis. Am Fam Physician. 2011 Oct 1;84(7):771-6.
  5. Acute Pyelonephritis in Adults. Johnson, JR and Russo, TA. New England Journal of Medicine 2018; 378:48-59.
  6. Sandberg T. et al. Ciprofloxacin for 7 days versus 14 days in women with acute pyelonephritis: a randomised, open-label and double-blind, placebo-controlled, non-inferiority trial. Lancet. 2012 Aug 4;380(9840):484-90.
  7. Norris DL, Young JD. UTI. EM Clin N Am. 2008; 26:413-30.
  8. Norris DL, Young JD. UTI. EM Clin N Am. 2008; 26:413-30.