Microscopic Examination Of Urine

Specimen Volume

• 10 and 15 mL

• 12 mL

Sternheimer-Malbin (consists of Crystal Violet and Safranin O

• Action: Delineates structure and contrasting colors

  of the nucleus and cytoplasm

• Function: Identifies WBCs, epithelial cells, and

  casts

0.5% Toluidine Blue 

• Enhances nuclear detail

• Differentiates WBCs and Renal Tubular Epithelial (RTE) cells

2% AceticAcid 

• Lyses RBCs and enhances nuclei of WBCs

• Distinguishes RBCs from WBCs, yeast, oil droplets, and crystals

Lipid Stains: Oil Red O and Sudan III

• stain triglycerides and neutral fats orange-red

• does not stain cholesterol

• Identify free droplets and lipid containing cells and cast

Gram Stain 

• Differentiates gram-positive (blue) and gram-negative (red) bacteria

• Identifies bacterial casts

Hansel Stain 

• Methylene Blue and Eosin Ystains eosinophilic granules

• Identifies urinary eosinophils

Prussian Blue Stain 

• Stains structures containing iron 

• Identifies yellow-brown granules of hemosiderin in cells and casts

RBCs

• Neutral – pink to purple

  Acid – pink (unstained)

  Alkaline – purple

WBCs (dark-staining cells)

Nuclei: Purple

Cytoplasm: Purple Granules

Glitter Cells (Sternheimer- Malbin positive cells)

Nuclei: Colorless or light blue 

Cytoplasm: Pale blue or gay

Brownian Movement

Renal Tubular Epithelial Cells

Nuclei: Dark shade of blue- purple

Cytoplasm: Light Shade of blue-purple

Bladder Tubular Epithelial Cells

Nuclei: Blue-purple 

Cytoplasm: Light purple

Squamous Epithelial Cells

• Nuclei: Dark shade of Orange-purple

• Cytoplasm: Light purple

Hyaline Casts 

• Pale pink/pale purple 

• Very uniform color; slightly darker than mucous threads

Coarse granular inclusion casts

Dark purple granules in purple matrix

Finely granular inclusion casts

Fine dark purple granules in pale pink or pale purple matrix

Waxy Casts 

• Pale pink/pale purple 

• Darker than hyaline casts, but of a pale even color; distinct broken ends

Fat Inclusion Casts 

• Fat globules unstained in a pink matrix

• Rare; present if polarized light indicates double refraction

Red cell inclusion casts

• Pink to orange-red 

• Intact cells can be seen in matrix

Blood (hemoglobin) casts

• Orange-red 

• No intact cells

Bacteria

• Motile: Do not stain

Trichomonas vaginalis

• Light blue-green

• Motility in unimpaired in fresh specimens when recommended volumes of stain are used; immobile organisms also identifiable

Mucus

Pale pink or pale blue

Bright-field microscopy 

Used for routine urinalysis

Phase-contrast microscopy 

Enhances visualization of elements with low

refractive indices, such as hyaline casts, mixed

cellular casts, mucous threads, and

Trichomonas

Polarizing Microscopy 

Aids in identification of cholesterol in oval fat

bodies, fatty casts, and crystals

Dark-field 

Often used for unstained specimens; and aids

in identification of Treponema pallidum

Fluorescence Microscopy 

Allows visualization of naturally fluorescent

microorganisms or those stained by a

fluorescent dye including labeled antigens and

antibodies

Interference-contrast 

Produces a three-dimensional microscopy

image and layer-by-layer imaging of a

specimen

Red Blood Cells

• Smooth, non-nucleated, biconcave disk

•  Crenated (irregular) – concentrated/hypersthenuric urine – cells shrink due to water los

Ghost cell 

dilute/hyposthenuric urine – large empty cells

Dysmorphic

associated with glomerular bleeding, seen after strenuous exercise

Presence of RBC in urine 

Macroscopic Hematuria – urine is cloudy with a red to brown color

Neutrophil

•  predominant WBC found in the urine sediment

•  Contains granules and are multi-lobed

  – Lyse rapidly in dilute alkaline urine

Glitter cells

• neutrophils exposed to hypotonic urine

• Sparkling appearance produced from the Brownian movement of the granules

Eosinophil

• may be seen with UTI and Renal Transplant Rejection, Interstitial Nephritis

Mononuclear cells 

lymphocytes, monocytes, macrophages, and histiocytes

WBC

 Glomerulonephritis, interstitial nephritis, lupus

erythematosus, tumor - nonbacterial

SQUAMOUS EPHITELIAL CELLS

• Squamous cells are the largest cells found in the urine sediment

• Good reference for focusing of the microscope.

• Squamous Cell

• Largest cell found in the urine sediment

• Contain abundant, irregular cytoplasm and a prominent central nucleus about the size of an RBC

• Originate from the linings of the vagina, female urethra, and the lower portion of male urethra

• No pathologic significance

Transitional Epithelial (Urothelial) Cell

• Can be Spherical, Polyhedral, or Caudate

• Centrally located nucleus

• Originate from the lining of the renal pelvis, calyces,

  ureters, and bladders, and from the upper portion of the

  male urethra

Renal Tubular Epithelial (RTE) Cell

• Rectangular (columnar or convoluted) shaped from Proximal

  Convoluted Tubule

• Oval or round shaped from Distal Convoluted Tubule

• Cuboidal shaped from Collecting Duct

• Eccentrically located nucleus

Oval Fat Bodies

• Lipid-containing, Highly refractile RTE cells

  Nephrotic syndrome -> Glomerular damage - Lipiduria

• Seen in Severe tubular necrosis and diabetes mellitus

• Bubble Cells – RTE cells containing large, nonlipid- filled vacuoles

Bacteria

• Small spherical and rod-shaped structures

  • Presence = UTI

  • Enterobacteriaceae – frequently associated with

  UTI

Yeast

• Small, oval, refractile structures with buds and/or

  mycelia

• Candida albicans – seen in the urine of diabetic patients, immunocompromised patients, and women with vaginal moniliasis

• Close resemblance: RBCs

• Reporting: Rare, few, moder

PARASITES

• Trichomonas vaginalis. (semiquanti per hpf)

• Schistosoma haematobium

• The most common contaminant is ova from the pinworm Enterobius

  vermicularis

Spermatozoa

• Tapered oval head with long, thin tail

• oval, slightly tapered heads and long, flagella-like tails

• Urine is toxic to spermatozoa; therefore, they rarely exhibit the motility observed when examining a semen specimen

Mucus

Single or clumped threads with a low refractive index

Uromodulin

•  major constituent of mucus

• A glycoprotein excreted by the RTE cells of the DCT and upper collecting ducts

CAST

• Formed within lumens of DCT and collecting

  ducts

  • Only elements found in the urinary sediment

  that are unique to the kidney

Uromodulin

major cast constituent

Hyaline Cast

• Colorless with low refractive index, homogenous matrix, prototype of all casts

• May normal parallel sides and rounded cells, cylindroid

  forms, and wrinkled or convoluted

• Pathologic - Glomerulonephritis,

  Pyelonephritis, Chronic Renal Disease, Congestive Heart

  Failure; Non-pathologic – strenuous exercise, dehydration,

  heat exposure, emotional stress

RBC Cast

• Orange-red color, cast matrix containing RBCs

• May exist as fragments or have a more irregular shape

• Clinical Significance: Glomerulonephritis, Strenuous exercise

WBC Cast

• Cast matrix containing WBCs

• Clinical Significance: Pyelonephritis,Acute

  interstitial nephritis (+eosinophils)

  • Primary marker for distinguishing

  Pyelonephritis (upper UTI) from cystitis

  (lower UTI)

Bacterial Cast

• Bacilli bound to protein matrix

• Clinical Significance: Pyelonephritis

Epithelial Cell Cast

• RTE cells attached to protein matrix

• Bilirubin-stained RTE – Hepatitis

Fatty Cast

• Fat droplets and oval fat bodies attached to protein matrix

• Close resemblance: Fecal Debris

Mixed Cellular Cast

Glomerulonephritis – RBC + WBC casts

• Pyelonephritis – WBC + RTE cell/Bacterial casts

Granular Cast

Coarse and fine granules in a cast matrix

• Lysosome (excreted by RTE cells) – where the granules in

nonpathologic condition originates

• Becomes Waxy when stayed in the tubules in extended

period

Broad Cast

Renal Failure Cast

• Wider than normal cast matrix

Waxy Cast

Highly refractile cast with jagged ends and notches;

brittle consistency

• Final phase of cast degeneration

Urinary Crystals

 Rarely of clinical significance

• Reporting: Rare, few, moderate, or many per hpf

(lpf for abnormal)

CRYSTAL FORMATION

ormed by the precipitation of urine solutes

•Temperature

•solute concentration

•pH

•Exception: calcium oxalate: precipitates on both acidic and alkaline urine

MANNER OF REPORTING OF CRYSTALS

Crystals: rare, few, moderate, or many per hpf

•Abnormal crystals may be averaged and reported per lpf.