The presence of white blood cells in the urine without bacterial growth.

Potential causes:

1. Infective
   • Sexually transmitted infection – chlamydia, gonorrhoea, trichomonas
   • Tuberculosis
   • (Partially) treated bacterial UTI
   • Atypical organism not routinely detected on culture – eg. Ureaplasma
2. Malignant
   • Bladder cancer / CIS
3. Urological inflammatory / benign
   • Stones
   • Stents or catheters
   • Conduit
   • Interstitial cystitis
   • Balanitis
   • Prostatitis
   • Post menopausal atrophy
4. Non urological inflammatory
   • Interstitial nephritis / medical renal disease
   • Papillary necrosis
   • Appendicitis
   • Diverticulitis / fistula
   • Sarcoidosis
   • Foreign body

Assessment and management

History

• Symptoms, haematuria, risk factors STI/UTI, pain, previous medical and surgical history, medications, travel history/risk factors for TB

Examination

• Focussed urological and pelvic exam

Investigation

• Repeat urine microscopy / culture
• Bloods – renal function
• STI testing if appropriate
• Ultrasound +/- CT IVP pending haematuria, suspicion for stones, etc
• Urine cytology and cystoscopy if haematuria, concerns for malignancy
• +/- cystoscopy if persistent sterile pyuria with unexplained cause