B

108.5 Microscopic Examination Chapter07 2022.23

Topic: Microscopic Examination of

Urine

Elements in urine during a microscopic examination

  • Red blood cells (RBCs)

  • WBC

  • Epithelial cells

  • Casts

  • Bacteria

  • Yeast

  • Parasites

  • Mucus

  • Spermatozoa

  • Crystals

  • Artifacts

    Specimen volume/Centrifugation

  • 12mL quantities

  • centrifuge 10 to 15mL of urine

  • Centrifuge for 5 min at 400 RCF

  • cap all specimens

  • RCF =

    Sediment Preparation/ Volume of sediment examined

  • Volume of sediment = 0.5 to 1.0mL/ 12:1 ratio ( 12 part centrifuged / 1 part sediment)

  • Urine should be aspirated off rather than poured off to control amount poured off

  • conventional glass slide method

  • 20uL sediment

  • 22 × 22 glass cover slip

  • do not overflow cover slip ( heavier elements such as casts flow outside)

    Reporting the examination

  • Casts = average per lpf (light power field)

  • RBC,WBC = average per hpf( high power field)

Epithelial cells, crystals in semiquantitative terms such as few, moderate, many, (1+, 2+. 3+, 4+) lpf or hpf

Correlating results


Sediment Examination Techniques

  • Factors that affect Sediment appearance

  • Cells and casts in various stages of development and degeneration

  • Distortion of cells and crystals by chemical content of the specimen

  • the presence of inclusions in cells and casts

  • Contamination by artifacts

Sediment Stains

  • Use to identify cellular structures such as ( Nuclei, Cytoplasm, Inclusions)

  • Stains = Supravital, Acetic Acid, Lipid, Gram, Hansel, Prussian Blue

  • Supravital

  • Most frequently use

  • Sternheimer-Malbin stain = crystal violet/ Safranin O

  • Dye absorbed well by WBC, epithelial cells, and casts

  • help differentiate WBC and renal tubular epithelial cells

  • Acetic Acid

  • Enhances nuclear detail of WBC and epithelial cells

  • RBC are lysed

  • Lipid

  • Appearance of free fat droplets and lipid containing cells and casts in the sediment

  • Use Oil Red O and Sudan III

  • Triglycerides/ neutral fats = stain orange- red

  • Cholesterol doesn’t stain

  • Gram

  • Use to differentiate gram + (blue) and gram - (red)

  • Help to identify bacterial Casts

  • Hansel Stain

  • Use to stain urinary eosinophils

  • consists of methylene blue and eosin y in methanol

  • Prussian Blue Stain

  • Hemosiderin granules

  • Stain for iron

  • Microscopy

  • RBC

  • Smooth, nonnucleated, biconcave disks ~7 µm

  • Crenated in hypersthenuric urine

  • Ghost cells in hyposthenuric urine


    Dysmorphic RBC

  • Glomerular bleeding

  • Strenuous exercise

  • Acanthocytic with multiple

  • protrusions

  • Hypochromic, blebs

  • Aid in diagnosis


    RBC Clinical Significance

  • damage to glomerular membrane or vascular

    injury to the genitourinary tract

  • Cloudy, red to brown urine, advanced disease,

    trauma, acute infection, coagulation disorders

  • Microscopic hematuria=early glomerular disease,

    malignancy, strenuous exercise, renal calculi

    confirmation

WBC

  • 12 µm

  • Neutrophil is predominant

  • Identify under high power

  • Glitter cells

  • Hypotonic urine

  • Brownian movement

  • Swell; granules sparkle

  • Light blue if stained

  • Nonpathologic

Glitter cell

Eosinophils (WBC)

  • Drug-induced interstitial

    nephritis

  • Renal transplant rejection

Mononuclear (WBC)

  • Lymphocytes, monocytes,

    macrophages, histiocytes are

    rare

Epithelial Cells

  • Squamous = vagina, male and female urethra

    ‒First structures observed

  • Transitional (urothelial)- bladder, renal pelvis, calyces, ureters, upper male urethra

  • Renal tubular epithelial (RTE)- renal tubules

    Squamous

  • Largest cell in urine

  • Good for focusing microscope

  • Rare, few, moderate, many

  • lpf or hpf per laboratory

  • Normal sloughing

  • Contamination if not midstream clean-catch

Transitional Epithelial Cells

  • Spherical: absorb water in bladder and become large and round

  • Polyhedral: multiple sides

  • Caudate: has a tail

Renal Tubular Epithelial Cells in Proximal Convoluted Tubule Cells

  • Larger than other RTEs

  • Columnar, convoluted, rectangular

  • May resemble casts

  • Coarsely granular cytoplasm

  • Examine for presence of nucleus


RTE ( Distal Convoluted Tubule Cells

  • Round or oval shaped,,smaller

  • May be mistaken for WBCs or spherical transitional cells

  • Observe the eccentrically placed nucleus to differentiate from spherical transitional