Microscopic Examination

• What is another name for microscopic examination in urine analysis?

  sediment examination
• What is the gold standard in routine urinalysis?

  microscopic examination
• What is the purpose of sediment examination in urine analysis?

  To detect, identify, and quantitate insoluble materials present in the urine
• How should the results of microscopic examination be correlated in urine analysis?

  With the physical and chemical examination results
• What is a disadvantage of sediment examination?

  It is the least standardized and most time-consuming method
• How can refrigerated urine samples affect cellular elements in urine analysis?

  They preserve almost all cellular elements, crystals, and casts very well
• What should be done to dissolve amorphous materials in refrigerated urine samples?

  Preheat the sample at 37°C
• Why is fresh and concentrated urine preferred for analysis?

  It provides more accurate results
• What effect does hypotonic urine have on cells and casts?

  It causes lysis of cells and casts
• What is the importance of proper collection techniques in urine analysis?

  To avoid extra debris from the urethral meatus and vaginal secretions
• Why is subdued light important in low power objective (LPO) microscopy?

  It is necessary for accurate results
• How soon should urine specimens be examined after collection?

  Within 1 to 2 hours
• How many representative fields should be examined in urine analysis?

  10 representative fields (10 LPO and 10 HPO)
• What does semi-quantitative reporting in urine analysis estimate?

  Rare, few, moderate, many
• What is the normal average count of RBCs in urine analysis?

  0 to 500,000/12-hr urine
• What is the normal average count of WBCs in urine analysis?

  0 to 1,200,000/12-hr urine
• What is the normal average count of hyaline casts in urine analysis?

  0 to 5,000/12-hr urine
• What are the microscopy techniques used in urine analysis and their functions?

  • Bright Field Microscopy: For routine urinalysis
  • Phase-contrast Microscopy: Enhances visualization of elements with low refractive indices
  • Polarizing Microscopy: Identification of cholesterol in oval fat bodies and crystals
  • Dark-Field Microscopy: Identification of T. Pallidum
  • Fluorescence Microscopy: Visualization of fluorescent microorganisms
  • Interference Microscopy: 3-D imaging and layer by layer imaging
• What role do abnormalities in physical and chemical urinalysis play?

  They influence the decision to perform a microscopic analysis
• What is the normal value range for RBCs in urine analysis?


  0-2 or 0-3/HPF
• What happens to RBCs in a hypertonic solution?

  They crenate or shrink
• What happens to RBCs in a hypotonic solution?

  They swell (hemolyze) or become ghost cells
• What indicates glomerular membrane damage in RBCs?

  Dysmorphic RBCs with projections
• What are common sources of error when analyzing RBCs?

  Yeasts, oil droplets, air bubbles, calcium oxalate crystals
• How can you lyse RBCs in urine analysis?

  Add 2% acetic acid
• What is the normal value range for WBCs in urine analysis?

  0-5 or 0-8/HPF
• Which type of WBC is most predominant in urine analysis?

  Neutrophils
• What happens to neutrophils in hypotonic urine?

  They swell and undergo Brownian movement
• What is the significance of eosinophils in urine analysis?

  Significant if >1%, associated with drug-induced interstitial nephritis
• What are the types of mononuclear cells found in urine?

  Lymphocytes, monocytes, macrophages, histiocytes
• What are squamous epithelial cells and where do they come from?

  Largest cells with abundant irregular cytoplasm from the linings of vagina, female urethra, and lower male urethra
• What are clue cells and their association?

  Squamous epithelial cells covered with Gardnerella vaginalis, associated with bacterial vaginosis
• What are transitional epithelial cells also known as?

  Urothelial cells
• Where do transitional epithelial cells originate from?

  From the renal pelvis, ureter, urinary bladder, and upper male urethra
• What is the reporting estimate for transitional epithelial cells?

  Estimate/HPF
• What is the significance of renal tubular epithelial cells (RTE)?

  They are the most clinically significant epithelial cells indicating tubular injury if >2 RTE/HPF
• What are the variations of RTE cells?

  Oval fat body and bubble cells
• What do oval fat bodies indicate?

  Lipiduria, seen in nephrotic syndrome
• How are lipid-containing RTE cells identified?

  By lipid stains (Oil Red O, Sudan III or IV) for triglyceride and polarizing microscope for cholesterol
• What do bubble cells indicate?

  RTE cells with nonlipid-filled vacuoles, seen in tubular necrosis