Clinmic

• Preparation and Examination of Urine Sediment

  1. Specimen volume: 10-15 ml (12ml if using conical tube)

  2. Centrifugation: 400-500 rcf for 5 minutes

  3. Sediment volume left after decantation: 0.5-1.0 ml

  4. Sediment volume for examination: 0.02 ml (20 ul)
• Reporting

  • RBC/WBC, RTE and oval fat bodies (clinically significant) - average # /HPF
  • Casts - average # /LPF
  • Epithelial cells, crystals and other sediments - +, rare, few, moderate, many
• Conical tube is used for microscopic examination of urine because the sediment yield increases
• Ocular lens/ Eye piece


  • Adjusted horizontally to adopt to differences in interpupillary distance between operators for optimal viewing conditions
  • Performs the final magnification
• Adjustment knob


  Can be rotated to compensate for variations in vision between the operator's eyes
• Objective lens


  Perform the initial magnification
• Rheostat


  Regulates light intensity
• Condenser


  Focuses light on the specimen
• Diaphragm


  Controls the amount and the angle of light that will pass through the specimen lens
• Lens System


  • Ocular
  • Objectives
  • Adjustment knob
• Illuminator System


  • Light source
  • Condenser
  • Diaphragm
• Bright field microscope


  • Used for routine urinalysis
  • Object appears dark against a light background
• Phase-contrast microscope


  • Enhances visualization of elements with low refractive indices
  • Works by retardation of light rays diffused by the object in focus, a halo effect is produced around the element, thereby producing better image reinforcement
  • Usually used for RBCs, hyaline casts, and mucus threads (examples of sediments with low refractive indices)
• Polarizing microscope


  • Aids in the identification of cholesterol in oval fat bodies, fatty casts, and crystals
  • Used to confirm the identification of fat droplets, oval fat bodies, and fatty casts
  • Used to evaluate substances with birefringence
  • Birefringence - the ability of the substance to refract or rotate light in two directions at 90 degree angle
  • Clockwise - positive birefringence
  • Counterclockwise - negative birefringence
  • Uses a halogen quartz lamp as its light source
• Dark field microscopy


  • Aids in Treponema pallidum identification
  • Object appears light against dark background
• Fluorescent microscope


  • Allow visualization of naturally fluorescent microorganism or those stained by fluorescent dye
• Interference contrast microscope


  • Produced a 3D microscopy image
  • Allows layer by layer imaging of the specimen
  • Object appears bright against a dark background but without the diffraction halo
  • Types: Nomarski (differential interference contrast), Hoffman (modulation contrast)
• From bright field to Polarizing


  Two polarizing filters in a crossed centrifugation

  (one in condenser, one in ocular lens)
• From bright field to Dark field microscope

  Replace condenser with dark field condenser
• From bright field to Interference Contrast Microscope

  1. Set up: Condenser to dark field condenser

  2. Polarizer between the light source and condenser

  3. Special condenser with modified Walla stone prism or each objective

  4. Walla stone prism between the objective and eyepiece

  5. Analyzer/polarizing filter behind the prism before the eyepiece
• Sternheimer-Malbin stain


  • Composed of CRYSTAL VIOLET AND SAFRANIN
  • Delineates structure and contrasting colors of the nucleus and cytoplasm
  • Identifies WBCs, epithelial cells and casts
• Toluidine blue stain


  • Enhances nuclear details
  • Differentiates WBCs and renal tubular epithelial cells
  • Supravital staining
• Lipid stains/Lysochromes


  • Stains TAG and neutral fats ORANGE-RED
  • Identifies free fat droplets and lipid containing cells
  • Examples: Oil red o, Sudan III
• Gram stain


  • Differentiates gram (+) and (-) bacteria
  • Identifies bacterial casts
• Hansel stain


  • Composed of METHYLENE BLUE AND EOSIN Y
  • Stains eosinophilic granules
  • Identifies urinary eosinophils
• Prussian blue stain


  • Stains structures containing iron
  • Identifies yellow-brown granules of hemosiderin in cells and cast
• Squamous epithelial cells


  • Seen in the vaginal lining and lower portions of the male urethra
  • Largest and most frequently seen and least significant cell in the urine sediment
  • Central nucleus about the size of an RBC and abundant irregular cytoplasm
  • CLUE CELLS: Squamous EC infected with G. vaginalis covering most of the cell surface extending beyond the cell's edges
• Transitional epithelial cells (Bladder Cells)


  • Found lining the renal pelvis, renal calyces, bladder and upper urethra
  • Spherical, caudate or polyhedral in shape with a centrally located nucleus (occasionally with two nuclei); pear shaped, tail-like projections
  • Has the ability to reabsorb large quantities of water
  • No significance in small amounts
  • SYNCYTIA: Increased numbers of transitional cells seen single, in pairs or in clumps; seen after an invasive urologic procedure
• Renal Tubular Epithelial Cells


  • Lines the renal tubules
  • Round and slightly larger than WBCs with a single, round, and eccentrically located nucleus
  • Most significant and indicates tubular injury (>2/HPF), tubular necrosis and renal graft rejection
  • OVAL FAT BODIES: RTE that contains lipids, found in lipiduria. Exhibit maltese cross formation. Associated with nephrotic syndrome
  • BUBBLE CELLS: RTE that contains large nonlipid filled vacuoles. Often associated with acute tubular necrosis
• Red Blood Cells


  • Swollen: Described as ghost/shadow cells; found in hypotonic urine
  • Crenated: Shining is due to hypertonic urine
  • Dysmorphic: Seen in glomerular membrane damage; glomerular bleeding
• Clinical significance of RBCs

  • Glomerulonephritis (massive hematuria)
  • Injury along the genitourinary tract
  • Renal lithiasis (slight intermittent hematuria)
• Neutrophils


  •Most frequently seen

  •Lyse rapidly in dilute alkaline urine, loss of nuclear detail (approximately 50% are loss within 2-3 hours)

  •Violet in Sternheimer-Malbin stain

  •GLITTER CELLS: are neutrophils absorbing water in hypotonic urine.

  -Characteristic sparking appearance due to Brownian movement of their cytoplasmic granules (stain light blue in Sternheimer-Malbin stain)

  -Referred to as Sternheimer-Malbin positive cells
• Clinical significance of eosinophils

  •>1% is considered significant

  ⁃Urinary eosinophils: determined in 100-500 cells

  •Highly associated with drug induced interstitial nephritis

  •May also be increased in UTI and renal transplant
• Mononuclear cells


  •Lymphocytes are the smallest and may resemble RBCs

  •Monocytes, macrophages, and histiocytes are large and may be vacuolated or could contain inclusions

  •Can be confused as RTE
• Clinical significance of mononuclear cells

  •Bacterial conditions

  -Pyelonephritis – UTI of the upper urinary tract o

  -Cystitis – infection of the bladder o

  -Prostatitis and Urethritis - lower UTI

  • Nonbacterial conditions (glomerulonephritis, SLE, tumors and interstitial nephritis)

  -Results to pyuria (presence of WBC in urine sterile inflammation)

  Note: There is WBC and WBC casts – Interstitial nephritis