Microscopic Examination of Urine

Routine Urinalysis Correlations

• Table 7-2: Summary of Correlations in Routine Urinalysis
  • Parameters Analyzed:
  • Hemolysis
  • Lysis
  • Microscopic Elements

Physical and Chemical Properties

• Red Blood Cells (RBCs):

  • Turbidity observed
  • Associated with:
    • +Blood
    • Red color in urine

• White Blood Cells (WBCs):

  • Turbidity noted
  • Associated with:
    • +Protein
    • +Nitrite
    • +Leukocyte Esterase (LE)

• Epithelial Cells:

  • Turbidity observed

• Casts:

  • Associated with:
    • +Protein
    • Turbidity present

• Bacteria:

  • Turbidity noted
  • Associated with:
    • +Nitrite
    • +Leukocytes

• Crystals:

  • Turbidity observed
  • Related to pH and type of crystals

• Color:

  • Associated with:
    • +Bilirubin

Sediment Stains in Microscopy

• Purpose of Sediment Stains:
  • Increases visibility of sediment elements during examination using bright-field microscopy.
  • Alters the refractive index of elements, improving identification of structures such as nuclei, cytoplasm, and inclusions.

Stains Utilized

• Sternheimer-Malbin Stain:

  • Composed of crystal violet and safranin O.
  • Commonly available under commercial names like Sedi-Stain and KOVA stain.
  • Stabilizing agents included to prevent precipitation.
  • Well absorbed by WBCs, epithelial cells, and casts, enhancing visibility of cellular structures.

• Toluidine Blue (0.5% solution):

  • A metachromatic stain enhancing nuclear details.
  • Useful for distinguishing between WBCs and renal tubular epithelial cells.
  • Also employed in examining cells from other body fluids.

• Acetic Acid (2%):

  • Enhances nuclear detail of WBCs and epithelial cells.
  • Not suitable for initial sediment analysis as it lyses RBCs.

Lipid Stains

• Detection of Lipids:
  • Lipids (triglycerides, neutral fats, cholesterol) can be detected in urine sediment due to their passage through the glomerular membrane.
  • Lipid stains Oil Red O and Sudan III confirm the presence of these components.
  • Triglycerides and neutral fats stain orange-red, while cholesterol does not stain but can be identified via polarization.

Table 7-3: Urine Sediment Stain Characteristics