Sterile Pyuria

Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Sterile pyuria is the presence of elevated numbers of white cells (>10 white cells/mm3) in urine which appears sterile using standard culture techniques.

  • Sterile pyuria is not an uncommon laboratory finding.[1]
  • Sterile pyuria is often found in female patients with symptoms of urinary tract infection (UTI). However, these results may be misleading for various reasons:
    • Standard laboratory culture conditions may not be optimal for growth of atypical organisms.
    • Laboratory may not report significant growth either because it was not a single organism or a recognised urinary pathogen.
    • Fewer than 100,000 colony-forming units (cfu) per mL reported - eg, it may be that urine was diluted by high fluid intake or an organism may be slow-growing. Studies have shown that approximately half of women presenting with symptoms and counts of 100-10,000 cfu/mL have genuine bladder infections.
  • The presence of pyuria increases the significance of a low bacterial count in the urine.
  • Cell count per high power field is inaccurate and use of a counting chamber or similar gives more accurate results.
  • Urinalysis: initial test to identify likely infection but a urine sample needs to be sent to the laboratory. See the separate article on Urine Dipstick Analysis. Positive nitrite test +/- positive leukocyte esterase test. Haematuria and proteinuria occur in UTI but are also present in other conditions.
  • Urine microscopy, culture and sensitivities; ask the laboratory to culture under conditions allowing identification of fastidious or slow-growing organisms.
  • Consider the possibility of sexually transmitted disease; take a sexual history and consider sending swabs for chlamydia and N. gonorrhoeae.
  • Polymerase chain reaction (PCR) testing of sterile pyuria has been recommended for the detection of Chlamydia trachomatis, mycoplasma and ureaplasma infections.[4]
  • Always consider tuberculosis; culture for AFBs (three early morning urine samples).
  • With urine obtained direct from the bladder, any organism grown is significant and should be treated with a prolonged course of appropriate antibiotics.
  • Cystoscopy may be required to exclude non-infective causes.
  • Management of any identified underlying cause.

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Original Author:
Dr Colin Tidy
Current Version:
Dr Colin Tidy
Peer Reviewer:
Dr John Cox
Document ID:
1054 (v23)
Last Checked:
24 February 2015
Next Review:
23 February 2020

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