Urinary tract infection

Last revised by Daniel J Bell on 2 Jul 2019

Citation, DOI, disclosures and article data

Citation:

Morgan M, Bell D, Hacking C, et al. Urinary tract infection. Reference article, Radiopaedia.org (Accessed on 18 Apr 2024) https://doi.org/10.53347/rID-40521

DOI:

https://doi.org/10.53347/rID-40521

Permalink:

https://radiopaedia.org/articles/40521

rID:

40521

Article created:

24 Oct 2015, Matt A. Morgan ◉

Disclosures:

At the time the article was created Matt A. Morgan had no recorded disclosures.

View Matt A. Morgan's current disclosures

Last revised:

2 Jul 2019, Daniel J Bell ◉

Disclosures:

At the time the article was last revised Daniel J Bell had no recorded disclosures.

View Daniel J Bell's current disclosures

Revisions:

8 times, by 7 contributors - see full revision history and disclosures

Systems:

Urogenital

Sections:

Approach

Tags:

urology, kidney, ureter, bladder, cases

Synonyms:

Urinary tract infections
UTIs
UTIs

Urinary tract infection (UTI) is a common clinical condition involving the bladder (cystitis) and kidneys (pyelonephritis). It is commonly divided into 'uncomplicated' and 'complicated' infections.

UTIs occur when there is bacterial colonisation of the uroepithelium and a subsequent inflammatory response. Classically, the urine and urinary collecting system were considered sterile, however, there is some debate on whether a small amount of bacterial colonisation is normal ⁵. Given this, and that voiding urinary samples may be contaminated by skin or rectal reservoir flora, bacteriuria is suggestive of a UTI, but bacteriuria and pyuria (white blood cells in the urine) is much more specific for infection.

Uncomplicated vs complicated UTI

uncomplicated: an otherwise healthy patient with a structurally and functionally normal urinary tract
complicated: factors are present that decrease the likelihood of therapy being effective
- urinary tract is structurally or functionally abnormal
- immunocompromised status
- especially virulent pathogen
- factors that may make a patient complicated ¹
  - male
  - childhood UTIs
  - immunocompromised
  - pregnancy
  - elderly
  - diabetes mellitus
  - failed antibiotic course
  - extended symptoms before presentation

Treatment and prognosis

Uncomplicated

These patients are usually well managed with a course of oral antibiotics.

Many imaging algorithms suggest that imaging for uncomplicated cystitis or pyelonephritis is unnecessary.

Complicated

These patients have often failed a course of antibiotics and may benefit from imaging:

lower urinary tract
- CT urography: for evaluation of structural abnormalities and possible abscess formation; MRI could be considered if the patient has an allergy to contrast
- ultrasound has a secondary role
upper urinary tract
- CT abdomen with contrast (or without and with contrast)
- MRI abdomen: for patients with contrast allergies and pregnant patients
- renal and bladder ultrasound: second line, relative to CT it is not as good at detecting renal parenchymal changes and/or characterising perinephric extension of infection