Lab

Microscopic Hematuria

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Microscopic Hematuria

  • Definition
  1. Microscopic Hematuria: 3 or more RBCs/hpf
  • Technique
  1. Start with 10 ml of midstream urine
  2. Centrifuge for approximately 10 minutes (typically at near 2000 rpm)
    1. Discard supernatant
    2. Suspend sediment in 0.3 ml saline or supernatant
  3. Examine under microscopy at 400x magnification
    1. Review at least 10-20 microscopic fields
  • Interpretation
  • Inadequate sample (contaminated with vaginal contents)
  1. Squamous epithelial cells >5/hpf
  • Interpretation
  • Negative - Normal (<3 RBCs/hpf)
  1. Interpret: Negative microscopy (<3 RBCs/hpf) and negative dipstick
    1. Normal
  2. Interpret: Negative microscopy, but positive dipstick
    1. See Urine Occult Blood for false positive causes
    2. May suggest Myoglobinuria or Hemoglobinuria
    3. Rhabdomyolysis
    4. Intravascular Hemolysis with circulating free Hemoglobin
      1. Causes include Transfusion Reaction, DIC, Hemolytic Uremic Syndrome
  3. Precautions
    1. See Microscopic Hematuria for repeat Urinalysis timing
  • Interpretation
  • Positive (3 or more RBCs per high powered field)