Microscopic Examination of Urine (F) Flashcards
What are the purposes of microscopic examination of urine?
To detect and identify insoluble mats present in the urine
What are the diff sources of formed elements to the urine?
1) Blood
2) Kidney
3) Lower GUT
4) External contamination
What are the formed element constituents of urine?
1) RBCs
2) WBCs
3) Epithelial cells
4) Casts
5) Crystals and artifacts
6) Bacteria, yeast, parasites
7) Mucus, sperm
Sxs should be examined while what?
While fresh or adequately preserved
What are the formed elements that disintegrate rapidly particularly in dilute alkaline urine?
1) RBCs
2) WBCs
3) Hyaline casts
What are the effects brought by refrigeration?
It may cause precipitation of amorphous urates and phosphates and other non-pathologic crystals that can obscure other elements in the urine sediment
If the (refrigerated?) sx is warmed to 37 DC prior to centrifuging, what happens?
Some crystals may dissolve
Dilute random sxs may cause what?
These sxs may cause false (-) readings
What should be done to a sx before decanting a portion of it into a centrifuge tube?
Thoroughly mix the sx
What is the std amt of sx volume and what is done to this sx volume?
10 - 15 mL is centrifuged in a conical tube
What is the ideal volume for rgnt strip testing?
12 mL
What is the purpose of centrifugation?
To produce an optimum amt of sediment w/ the least chance of damaging the elements
What is the RCF for centrifugation (of urine?)?
400 RCF
What is the speed for centrifugation (of urine?)?
1,500 - 2,000 rpm
What is the time duration of centrifugation (of urine?)?
3 - 5 mins
What is the purpose of tachometer?
Instrument that measures the speed in rpm
What should remain in the tube after decantation?
A uniform amt of urine and sediment should remain
What are the volumes of urine and sediment that should remain the tube after decantation?
0.5 and 1.0 mL respectively
How is concentration factor obtained?
It is the volume of urine centrifuged divided by the sediment volume
What should be done to maintain a uniform sediment concentration factor?
Urine should be aspirated off rather than poured off
What must be done to the sediment?
It must be thoroughly resuspended by gentle agitation
What is the recommended volume of sediment to be examined?
20 uL (0.02 mL)
What should be done to 20 uL of sediment for examination?
It should be covered by a 22 X 22 mm glass cover slip
Allowing the sx to flow outside the cover slip may result in what?
It may result in the loss of heavier elements such as casts
How should microscopic examination be performed (in terms of # of fields)?
Microscopic examination should be performed by observation of a min of 10 fields under both low (10x) and high (40x) power
What is the purpose of LPO (in terms of examination of sediment)?
The slide is first examined under low power to detect casts and to ascertain the general composition of the sediment
What is the purpose of HPO (in terms of examination of sediment)?
To identify elements such as casts
Casts have the tendency to what?
To locate near the edges of the cover slip
Due to the tendency done by casts, what is recommended to be done?
Low power scanning the cover slip parameter is recommended
If the urine sediment is examined under reduced light, what is the result?
Many sediment constituents have a refractive index similar to urine
How are casts reported (via microscopic examination)?
They are reported as the ave # per lpf following examination of 10 fields
How are RBCs and WBCs reported (via microscopic examination)?
They are reported as # per 10 hpfs
How are epithelial cells, crystals, and other elements of urine frequently reported (via microscopic examination)?
They are reported in semiquantitative terms such as rare, few, moderate, and many, or as 1+, 2+, 3+, and 4+
What is the significance of the given screening test?
Screening test: Color
Blood
What is the significance of the given screening test?
Screening test: Clarity
Hematuria vs Hemoglobinuria or myoglobinuria
Confirm pathologic or non-pathologic cause of turbidity
What is the significance of the given screening test?
Screening test: Blood
RBCs
What is the significance of the given screening test?
Screening test: Protein
Casts and cells
What is the significance of the given screening test?
Screening test: Nitrite
Bacteria and WBCs
What is the significance of the given screening test?
Screening test: LE
WBCs, WBC casts, and bacteria
What is the significance of the given screening test?
Screening test: Glucose
Yeast
What is Addis count?
It is the 1st procedure to standardize the quantitation of formed elements in the urine microscopic analysis
When is Addis count discovered(?)?
1926
What is used in Addis count (including its functions)?
Hemocytometer is used to ct the # of RBCs, WBCs, casts, and epithelial cells present in a 12 hr sx
What is the range of normal value for RBCs in Addis ct?
0 - 500,000 RBCs
What is the range of normal value for hyaline casts in Addis ct?
0 - 5,000 hyaline casts
What is the range of normal value for WBCs and epithelial cells in Addis ct?
0 - 1,800,000 WBCs and epithelial cells
What are the purposes of stains (for urine sediments)?
1) It increases the overall visibility of sediment elements being examined
2) It also imparts identifying characteristics to cellular structures
(such as the nuclei, cytoplasm, and inclusions)
What is principle of microscopy (including its action) is used for microscopic examination of stained urine sediments?
Bright-field microscopy by changing the refractive index of urine sediments
What is the most frequently used stain?
Sternheimer-Malbin stain
What are the components of Sternheimer-Malbin stain?
1) CV
2) Safranin O
What are the actions of Sternheimer-Malbin stain?
1) Delineates structure
2) Contrasting colors of the nucleus and cytoplasm
What are the functions of Sternheimer-Malbin stain?
Identifies:
1) WBCs
2) Epithelial cells
3) Casts
What is the characteristic of 0.5% toluidine blue?
It is a metachromatic stain
What is the action of 0.5% toluidine blue?
Provides enhancement of nuclear detail
What is the function of 0.5% toluidine blue?
Differentiates WBCs and renal tubular epithelial (RTE) cells
What is the purpose of 0.5% toluidine blue?
It is used in the examination of cells from other body fluids
What is the purpose of 2% acetic acid?
To enhance nuclear details
What are the actions of 2% acetic acid?
1) Lyses RBCs
2) Enhances nuclei of WBCs
What is the function of 2% acetic acid?
Distinguishes RBCs from WBCs, yeast, oil droplets, and crystals
What are the exs of lipid stains?
1) Oil Red O
2) Sudan III stains
What is the function of lipid stains?
Identify free fat droplets and lipid-containing cells and casts
What is the action by lipid stains?
Stain trigly and neutral fats orange-red
Do not stain chole
What are the purposes of gram stain?
1) Differentiates gram (+) and gram (-) bacteria
2) Identifies bacterial casts
What is the action of Hansel stain?
Methylene blue and eosin Y stains eosinophilic granules red (others are blue)
What is the function of Hansel stain?
Identifies urinary eosinophils
What is the term called if a pt has eosinophils present in his or her urine?
Eosinophiluria
What is the action of prussian blue stain?
Stains structures containing iron
What is the function of prussian blue stain?
Identifies yellow-brown granules of hemosiderin in cells and casts
What are the diff types of microscopy?
1) Bright-field microscopy
2) Phase-contrast microscopy
3) Dark-field microscopy
4) Polarizing microscopy
5) Fluorescence microscopy
6) Interference-contrast microscopy
What is the purpose of bright-field microscopy?
It is used for routine microscopic examinations
What is the function of phase-contrast microscopy?
To enhance the visualization of elements w/ low refractive indices (such as hyaline casts, mixed cellular casts, mucous threads, and Trichomonas)
What are the purposes of dark-field microscopy?
1) It is used for unstained sxs
2) It aids in the identification of Treponema pallidum
What is the purpose of polarizing microscopy?
It aids in the identification of chole in oval fat bodies, fatty casts, fat droplets, and crystals
Lipids and crystals have the ability to what?
To rotate the path of the unidirectional polarized light beam to produce characteristic colors in crystals and Maltese cross formation in lipids
What is birefringent?
Refract light in 2 dimensions at 90 deg to each other
What are the 2 types of birefringence?
1) Positive birefringence
2) Negative birefringence
What is (+) birefringence?
Substance that rotates the plane of polarized light 90 deg in a clockwise direction
What is (-) birefringence?
Substance that rotates the plane in a counterclockwise direction
What is the purpose of fluorescence microscopy?
It allows the visualization of naturally fluorescent microorganisms or those stained by a fluorescent dye including labeled Ags and Abs
What is the function of interference-contrast microscopy?
It produces a three-dimensional microscopy image and layer by layer imaging of a sx
What are the characteristics of RBCs (as urine sediment)?
1) Non-nucleated biconcave disks
2) Crenated in hypertonic urine (hypersthenuric)
3) Ghost cells in hypotonic urine or diluted urine (hyposthenuric)
4) Dysmorphic RBC (vary in size, have cellular protrusions, or are fragmented) seen in glomerular membrane damage
What are the sources of identification error for RBCs (as urine sediment)?
1) Yeast cells
2) Oil droplets
3) Air bubbles
What is the manner of reporting RBCs (as urine sediment)?
Average # per 10 hpfs
At what tests can RBCs (as urine sediment) be correlated?
Color and rgnt strip blood rxn
What are the clinical significance of RBCs (as urine sediment)?
1) Associated w/ damage to the glomerular membrane
2) Vascular injury within genitourinary tract
3) Microscopic hematuria: glomerular disorders and malignancy of the urinary tract and the presence of renal calculi
What are the types of RBCs (as urine sediment)?
1) Eumorphic RBC
2) Dysmorphic RBC
What are the characteristics of WBCs (as urine sediment)?
1) Larger than RBCs
2) Granulated, multilobed neutrophils
3) Glitter cells in hypotonic urine
4) Mononuclear cells w/ abundant cytoplasm
What is the source of identification error for WBCs (as urine sediment)?
RTE cells
What is the manner of reporting WBCs (as urine sediment)?
Ave # per 10 hpfs
At what tests can WBCs (as urine sediment) be correlated?
1) LE
2) Nitrite
3) SG
4) pH
What are the characteristics of neutrophils?
1) They lyse rapidly in dilute alkaline urine and begin to lose nuclear detail
2) If exposed to hypotonic urine, it absorbs H2O and swell
3) They are stained light blue w/ Sternheimer-Malbin stain
What is the characteristic of glitter cells?
These are cells that produce a sparkling appearance due to the Brownian movement of the granules within the cells
What are the clinical significance of WBCs (as urine sediment)?
1) Pyuria
2) Indicates inflammation or infection of the GUT
3) Bacterial infections: pyelonephritis, cystitis, prostatitis, and urethritis
4) Urinary calculi
5) Tumors and neoplasia
6) Glomerulonephritis, lupus erythematosus, and interstitial nephritis
7) Contamination of vaginal and prostate secretions
What is pyuria?
It is the presence of of increased #s of WBCs in the urine sediment (normal: < 5 WBCs/hpf)
What are the characteristics of urinary eosinophils?
1) They are primarily associated w/ drug-induced interstitial nephritis
2) Small #s may be seen w/ UTI and renal transplant rejection
3) Urine sediment may be concentrated by routine centrifugation alone or w/ cytocentrifugation
4) Not normally seen in the urine
What is the preferred stain for eosinophils (as urine sediment)?
Hansel’s stain, but Wright’s stain can also be used
Are eosinophils normally seen in the urine (as urine sediment)?
No, hence, the finding of > 1% eosinophils is considered significant
When are mononuclear cells seen in urine?
They are seen in increased #s in the early stages of renal transplant rejection
True or False
Lymphocytes, monocytes, macrophages, and histiocytes may be present in large #s and are usually not identified in the wet preparation urine microscopic analysis
False, because lymphocytes, monocytes, macrophages, and histiocytes may be present in small #s
True or False
Monocytes, macrophages, and histiocytes are small cells and may appear vacuolated or contain inclusions
False, because monocytes, macrophages, and histiocytes are large cells
What is cytodiagnostic urine testing?
It is the test done if sxs containing an increased amt of mononuclear cells cannot be identified as epithelial cells
What are the characteristics of squamous cells (as urine sediment)?
1) They are the largest cells found in the urine sediment
2) They contain abundant, irregular cytoplasm, and a prominent nucleus
3) Usually at least a few squamous epithelial cells are present in the urine sediment
4) They can serve as a good reference for focusing of the microscope
5) Squamous epithelial cells are commonly reported in terms of rare, few, moderate, or many, in terms of low power
What are the characteristics of clue cells?
1) A variation of the squamous epithelial cell w/ pathologic significance
2) They appear as squamous epithelial cells covered w/ the gram variable bacteria (Gardnerella coccobacillus) throughout the surface and extend beyond the edges of the cell
Clue cells are indicative of what?
They are indicative of vaginal infection