Pyuria

The presence of elevated numbers of white cells in the urine is termed pyuria, the most common cause of which is a urinary tract infection.

More than 10 white blood cells per cubic millimeter of mid-stream urine is abnormal.

The phenomenon of sterile pyuria is the presence of elevated numbers of white cells in a urine which appears sterile using standard culture techniques.

Summary Notes (1):

• white cell value in MSU result
  • white cells >= 10^4/mL are considered to represent inflammation
  • in adults no white cells present indicates no inflammation & reduces culture significance
  • pregnancy is associated with physiological pyuria
  • sterile pyuria
    • in sterile pyuria consider Chlamydia trachomatis (especially if 16-24 years), other vaginal infections, other non-culturable organisms, including TB or renal pathology

Reference:

• 1) Health Protection Agency (Accessed April 21/4/14). Diiagnosis of UTI Quiick Reference Guide for Primary Care.