A6. Pyuria and its examination

From greek.doctor

Pyuria or leukocyturia refers to >5 WBCs per field of view at 400x. The urine may be grossly cloudy.

  • Dipsticks
    • Can test for the presence of leukocyte esterase, an enzyme produced by WBCs
    • Can test for nitrite -> positive indicates bacteriuria
      • However, it can be false negative (bacteria which don’t produce nitrite)
  • Bacterial urine culture should be performed to check for bacteriuria
    • If culture is negative, it should be repeated
  • Meares and Stamey’s 4-glass urine collection
    • Used to determine the location of the bacterial infection within the urinary tract
    • Only performed in men
    • Four glasses are taken
      • 1st glass – the first 10 mL of urine
      • The patient then voids another approx. 100 mL of urine
      • 2nd glass – another 10 mL of urine
      • 3rd glass – the patient’s prostate is massaged, and the fluid ejected from the urethra is collected
      • 4th glass – another 10 mL of urine after the prostate massage
    • The first glass represents the urethral specimen
    • The second glass represents the bladder specimen
    • The third and fourth glasses represent the prostate specimen
    • Each glass is cultured for bacteria and examined for WBCs -> which glass has bacteria will give information on the location of the infection
  • Causes of bacteriuria + pyuria
    • Urinary tract infection
  • Causes of sterile pyuria (no bacteriuria)
    • Infection which is treated with Abs
    • Stone
    • Mycobacterial or chlamydial infection
    • Presence or recent use of catheter or endoscopic procedure
  • Causes of sterile pyuria with haematuria
    • Bladder cancer
    • Glomerulonephritis
    • Pyelonephritis
    • Interstitial nephritis
  • Causes of bacteriuria without pyuria
    • Bacterial colonization of urine sample