Mircoscopic examination of urine

Question 1

How much urine is used?

Answer 1

12 mL

Question 2

Centrifugation

Answer 2

speed: 400-450 g for 5 minutes, no brake.

Question 3

urine volume to resuspend sediment ration

Answer 3

12:1 ratio desired

Question 4

Low power objective?

Answer 4

10x objective, examine perimeter of cover-slip, look for squamous epithelial cells, casts, and mucus. Scan minimum of 10 fields

Question 5

high power objective?

Answer 5

40x, examine center area and look for RBC/WBC< transitional and renal tubular epithelial cells, bacteria, yeast, sperm, trichomonads, crystals

Question 6

Red blood cells:

Answer 6

intact RBC: hematuria

normal: 0-3/hpf
abnormal: damage to basement membrane of glomerulus, kidney infection, kidney stones, trauma

Question 7

What do RBC look like?

Answer 7

smooth biconcave discs, no nucleus

Question 8

Crenate RBC

Answer 8

seen in concentrated urine( high SG), water leaves RBC

Question 9

Ghost RBC

Answer 9

occurs in dilute urine when RBC swells and water enters cell and burst

Question 10

What do RBC resemble?

Answer 10

yeast, oil droplets, air bubbles, calcium oxalate crystals, WBC

Question 11

WBC: leukocytes

Answer 11

indicates infection. normal: 0-5, neutrophil is predominant type of WBC found in urine

Question 12

what do WBC’s look like?

Answer 12

spherical, contain segmented nucleus, granules, 2x larger than RBC, can be found in clumps

Question 13

What happens to WBC in dilute urine?

Answer 13

WBC swell and lyse, GLitter cells

Question 14

what happens to WBC in concentrated urine?

Answer 14

WBC become smaller, do not crenate

Question 15

what can WBCs resemble?

Answer 15

renal tubular epithelial cells, crenated RBCS

Question 16

WBC physical and chemical correlation?

Answer 16

physical exam: odor/clarity
chemical: positive reagent strip for leukocyte esterase, non-granular WBC will not react with reagent strip reaction (false negative)

Question 17

Why are epithelial cells in urine?

Answer 17

normal sloughing, inflammation, renal disease, common contaminant in femal species

Question 18

squamous epithelial cells

Answer 18

most common type, largest, originates in superficial lining of urethra and vagina, increased numbers may mean poor collection technique

Question 19

Transitional epithelial cells

Answer 19

originates in lining of renal pelvis, ureters, bladder, and upper urethra. Increased numbers may indicate urinary tract infection, or collection by catheterization, and malignancy

Question 20

renal tubular epithelial cells

Answer 20

originates in lining of renal tubules, increased numbers indicate tubular necrosis

Question 21

squamous epithelial cells under microscope

Answer 21

enumerate using low power, cells are thin and flat, central nucleus, fine granulation in cytoplasm

Question 22

clue cells

Answer 22

squamous epithelial cells with large amount of bacteria adhering to them, “shaggy”, originates in vaginal mucosa, indicates bacterial vaginal infection

Question 23

transitional epithelial cells unde rmicroscope

Answer 23

most common type is from bladder, larger than WBC< nucleus to cytoplasm ration is 1:5, nucleus in center, use high power

Question 24

renal tubular epithelial cell under microscope

Answer 24

shape varies, usually slightly larger than WBC< nucleus is eccentric, nucleus to cytoplasm ration 1:1, high power objective,

Question 25

oval fat bodies

Answer 25

RTE cell with absorbed fat, , maltese cross to verify, may also see free floating fat droplets, indicates pathology, use high power

Question 26

casts:

Answer 26

normal: few hyaline or few granular casts abnormal: increased number and type of cast significant. RBC/WBC always pathologic only formed in kidney

Question 27

what is in a cast?

Answer 27

consists of uromodulin matrix, formerly called Tamm-Horsfall protein, does not react with protein reagent strip test

Question 28

what enhances cast formation?

Answer 28

acidity of urine, increased solute concentration, decreased urine flow rate, presence of plasma proteins

Question 29

characteristics of casts

Answer 29

cylindrical, cigar shape, parallel sides, vary in length and width, mucus and fibers can be misidentified as casts

Question 30

Cast identification/calssification

Answer 30

enumerate using low power objective; identify using high power objective

Question 31

what is the youngest cast?

Answer 31

hyaline

Question 32

what is the oldest cast

Answer 32

waxy

Question 33

hyaline cast

Answer 33

hard to see in bright field microscopy, most common cast, normal: 0-2, increased amounts seen in dehydration, fever, emotional stress, strenuous exercise

Question 34

RBC cast

Answer 34

RBC inside a hyaline cast, , cast may appear yellow to reddish-brown, always pathologic

Question 35

WBC cast

Answer 35

WBC inside hyaline cast, look for lobed nucleus, always pathologic

Question 36

granular cast

Answer 36

aged cellular cast: fine or coarse granules, pathologic if increased

Question 37

waxy cast

Answer 37

highly retractile, homogeneous texture, well defined edges, blunt uneven ends, may see cracks along length of cast, may appear yellow to gray to colorless. pathologic: prolonged stasis

Question 38

fatty cast

Answer 38

highly refactile, fatin form of free fat droplets or oval fat bodies inside cast, use polarized microscopy, pathologic finding, often seen in nephrotic syndrome

Question 39

crystals

Answer 39

not normally found in fresh urine, if in fresh urine is pathologic, usually found in acidic urine

Question 40

what enhances crystal formation

Answer 40

increased concentration of solute, urine pH, urine stasis, temperature

Question 41

Normal acid pH crystals

Answer 41

amorphous urates, uric acid, calcium oxalate

Question 42

amorphous urate

Answer 42

normal acid pH crystal, look like sand, often seen after urine is refrigerated, pink sediment after urine centrifugation

Question 43

uric acid crystals

Answer 43

acid pH urine, many forms, multicolored when polarized, diamond shaped most common form

Question 44

calcium oxalate crystals

Answer 44

acid pH urine, most frequently observed crystal in urine, most common form is octahedryl shape "envelope", multicolored when polarized

Question 45

normal alkaline pH crystals

Answer 45

amorphous phosphates, triple phosphate, ammonium biurate

Question 46

amorphous phosphates

Answer 46

no distinct form, sand like, alkaline pH urine, seen after urine is refigerated

Question 47

triple phosphate crystals

Answer 47

most frequently seen in alkaline urine, colorless, prisms, coffin lid crystals

Question 48

ammonium biurate crystals

Answer 48

alkaline pH urine, yellow spheres with spicules on surface, thorny apple crystals, significant if fresh urine

Question 49

pathologic crystals:

Answer 49

cystine, tyrosine, leucine, cholesterol, bilirubin

Question 50

cystine crystals

Answer 50

colorless hexagonal plates, do not polarize, can be confused with uric acid crystals. Rare

Question 51

cholesterol crystals

Answer 51

clear, large, flat, rectanglue plates with notched corners, multicolored when polarized,also should see proteinuria and lipiduria

Question 52

leucine crystals

Answer 52

yellow-brown spheres with concentric circles on surface (tree trunk), can resemble free fat globules

Question 53

tyrosine crystals

Answer 53

colorless or yellow-brown fine delicate needles

Question 54

bilirubin crystals

Answer 54

yellow-brown small clusters of needles or granules, must confirm with positive ictotest, when present in urine, indicate large amount is present

Question 55

bacteria

Answer 55

most often rod-shaped, vary in size, use high power, presence may indicate UTI/contamination, usually alkaline pH

Question 56

yeast and mycelial elements

Answer 56

budding forms or singly, ovoid and more refractile than RBC, will not lyse iwth acetic acid or KOH,

Question 57

trichomonas vaginalis

Answer 57

round to lemon pear shape, undulating membrane and flagella, STD,