A6. Pyuria and its examination

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