microscopic

• What is the purpose of microscopic examination of urine?


  To detect and identify insoluble materials in urine
• What factors contribute to formed elements in urine?

  • Blood
  • Kidney
  • Lower Genitourinary
  • External Contaminants
• What are the inclusions of formed elements in urine?

  • RBC
  • WBC
  • Epithelial cells
  • Casts
  • Bacteria
  • Yeast
  • Parasites
  • Mucus
  • Spermatozoa
  • Crystals
  • Artifacts
• What are the procedural variations in urine microscopy?


  • Methods of sediment preparation
  • Volume of examined sediment
  • Methods and equipment for visualization
  • Manner of reporting
• What determines the necessity of a microscopic examination in urine analysis?


  Physical and Chemical tests indicate if microscopic exam is necessary
• What situations require microscopic examination according to CLSI?


  • Physician Request
  • Test for patient population
  • Abnormalities in Physical and Chemical tests
• What is the preferred specimen for urine analysis?


  Fresh or adequately preserved specimen
• What is the preferred collection method for urine specimens?

  Clean-catch midstream specimen
• What happens to formed elements in dilute alkaline urine?


  They undergo rapid disintegration
• What effect does refrigeration have on urine specimens?


  It causes amorphous urates and phosphates
• What is the purpose of warming urine to 37°C before centrifugation?


  To dissolve crystals
• What is the standard specimen volume for urine analysis?


  10-15 mL
• What is the volume required for reagent strips and capped centrifuge tubes?


  12 mL
• What is the significance of consistent speed and time during centrifugation?


  It ensures optimum sediment amount with low risk of element damage
• What is the formula to calculate RCF in centrifugation?


  $RCF =$$1.118 \times 10^{-5} \times \text{radius in centimeters} \times \text{RPM}^2$
• What is the importance of calibration in centrifugation?


  It ensures accurate and consistent results
• What is the effect of braking during centrifugation?


  It can disrupt sediment
• What is the purpose of capped tubes in centrifugation?


  To prevent aerosol formation
• What should remain in the tube after decantation?


  A uniform amount of urine and sediment
• What is the concentration factor in sediment preparation?


  Urine volume/Sediment Volume
• Why is it important to maintain a uniform sediment concentration factor?


  To detect elements present in low quantities
• What is the recommended method for aspirating urine?


  Urine should be aspirated off rather than poured off
• What is the purpose of gentle agitation during specimen resuspension?


  To ensure equal distribution of elements in fields
• What is the volume of sediment placed on the microscope slide?


  20 µL (0.02 mL)
• What is the size of the cover slip used in the glass slide method?


  22x22 mm
• What happens if the specimen flows outside the slide?


  There is a loss of elements
• What do commercial systems provide for urine sediment examination?

  • Capped, calibrated centrifuge tubes
  • Decant pipettes for sediment control
  • Slides for consistent sediment layers
  • Calibration grids for quantitation
• How many fields should be examined in sediment analysis?


  Minimum of 10 fields
• What is the purpose of examining slides under LPO?


  To detect casts and sediment composition
• What is the purpose of examining slides under HPO?


  To identify casts
• Where should casts be located on the slide?


  At the cover slip edges
• What is the recommended method for unstained microscopy?

  Bright-field microscopy
• What is the significance of the epithelial cell as a point of reference?


  It helps in focusing and identifying elements
• How should casts be reported after examining 10 fields in LPF?


  After 10 fields in Low Power Field (LPF)
• How should WBC and RBC be reported after examining 10 fields in HPF?


  After 10 fields in High Power Field (HPF)
• How are epithelial cells, crystals, and other elements reported?


  • Semiquantitative: Rare, Few, Moderate, Many
  • Scoring: 1+, 2+, 3+, 4+
• Why should reference values always be used in reporting?


  They provide a basis for the concentration factor
• What are the correlations between microscopic elements and physical/chemical tests?


  • RBC: Turbidity + Blood
  • WBC: Turbidity + Protein
  • Epithelial Cells: Turbidity
  • Casts: + Protein
  • Bacteria: Turbidity + High pH
  • Crystals: Turbidity + pH
• What is the purpose of stains in microscopy?


  To increase the visibility of elements in bright-field microscopy
• What are the components of Sternheimer-Malbin Stain?


  • Crystal Violet
  • Safranin O