Sterile Pyuria

Sterile pyuria

Sterile pyuria (the presence of >10 WBC per high powered field on formal urine microscopy, in the absence of infection with standard culture techniques) has a number of possible causes, the most common being:

• a treated UTI, within 2 weeks of treatment
• an inadequately treated (UTI)
• contamination of the urine sample by sterilizing solution
• contamination of the urine sample with vaginal leukocytes

Please refer if these have been ruled out, and there is no other chronic cause that doesn’t require treatment.

Other Possible causes of sterile pyuria include:

• urinary tract calculi
• prostatitis
• chlamydia/ N. gonorrhoea urethritis
• renal papillary necrosis
• tubulo-interstitial nephritis
• interstitial cystitis (rarely, this is a difficult diagnosis to make)
• urinary tract neoplasm
• polycystic kidney
• pyuria of pregnancy
• recent urinary tract surgery/catheter
• appendicitis
• pelvic irradiation
• genitourinary tuberculosis (rare, but consider in risk groups- do 3 early morning urines)
• Schistosomiasis (rare, but consider in high risk groups)
• paracetamol (rare)
• SLE

Many of these will also present with microscopic haematuria, which needs referral if appropriate.