Microscopic Sedimentation Evaluation of Urine: Crystals, Casts, RBC/WBC, Epithelial Cells

Sediment Examination

looking at cellular components of urine for the detection and evaluation of renal and urinary tract disorders and other systemic diseases

What is the urine collection method for viewing sedimentation?

cystocentesis

How much urine is collecting for sedimentation examination?

5-10 mL

Wet Mount

urine placed in plastic centrifuge tube or RTT
centrifuged at 1,000-2,000 rpm for 3-5 mins
supernatant is noted BEFORE pouring most of it out
use pipette to resuspend sediment from bottom of tube
place a drop onto slide and cover with a cover slip
examine under 10x and 40x w/ low light

What is noted BEFORE pouring it out?

supernatant

What objective(s) is used to examine the sediments?

10x and 40x to increase refractility of the cells

What is the time frame of when you should examine the urine?

30 mins after collection

What can be seen at 10x?

crystals and casts

How do you QUANITFY the specific structures seen ON 10x?

view 10 fields, quantify the numbers, find the average, and are reported per low powered field = /LPF

What can be seen at 40x?

leukocytes, erythrocytes, epithelial cells, fat droplets, crystals, casts, sperm, debris, and bacteria

How do you QUANTIFY the specific structures seen ON 40x?

scan the ENTIRE cover slip and reported per high powered field = /HPF

How are crystals and casts identified and reported?

number per low-power field (on 10x) by giving a range

How are RBCs, WBCs, epithelial cells, crystals, and casts reported?

a range per high-power field (40x)

How are Bacteria reported?

few, moderate, many OR 1+, 2+, 3+, 4+
need to specify what type it is

Dry Mount

centrifuge the urine
pour out the substance
use a pipette to grab pellet at bottom of tube
place small drop onto a slide
use another slide to smear the sample across to form a monolayer
allow sample to dry
stain the sample using Diff-Quik

Microscopic Evaluation Methods

wet mount and dry mounting

What is the MAIN difference between Wet and Dry Mount?

just place a cover slip over the slide vs spreading the sample to form a monolayer

How do Crystals Form?

urine that is static, supersaturated, solubility, or pH is altered

Where do Crystals Form?

any part of the urinary tract

What can the formation of Crystals result in?

calculi (stone) formation

What Influences Crystals to form?

pH, temperature, concentration, medication, time of collection, disease, state of patient, toxins

Crystalluria

crystals in urine

Urolithiasis

formation of urinary calculi

Grit/Sand

small pieces of calculi

How are CRYSTALS reported?

number per LPF (10x), few/moderate/many, or 1+/2+/3+/4+

What can Crystals tell you?

disorders predisposing P to uroliths
estimate mineral composition of uroliths
evaluate effectiveness of medicine for urolithiasis
detect liver dz
detect metabolic dz
detect toxicity

Crystal: Amorphous

debris-like appearance
can be: urates, phosphates, or xanthine
no clinical significance

Crystal: Struvite

AKA magnesium ammonium phosphate OR triple phosphate
has 6-8 sided prisons w/ tapering sides
form in: stagnant/retained urine, chronic cystitis, "blocked cats"

Amorphous

Struvite

Crystal: Calcium Oxalate Dihydrate

has small squares w/ "x"
found in: acidic or neutral urine
common in small #'s in dogs and cats

Calcium Oxalate Dihydrate

Crystal: Calcium Oxalate Monohydrate

has elongated, flat, pointed ends OR "dumb bell"
forms in: ethylene glycol poisoning
time-dependent and occur 6-18 hrs after ingestion

Calcium Oxalate Monohydrate

Crystal: Bilirubin

orange-reddish appearance w/ needle-like crystals
in LOW numbers is normal for dogs
in HIGH numbers in DOGS and OTHER ANIMALS = hemolysis or liver issues

Bilirubin

Crystal: Ammonium Biurate

AKA ammonium urate and nickname: thornapple crystal
brown, round w/ long irregular spikes appearance
present in severe liver disease
NORMAL in dalmations and bulldogs

Ammonium Biurate

Crystal: Uric Acid

yellow or yellow-brown color and is pleiomorphic (many shapes)
COMMON in dalmations
UNCOMMON in other animals but represents liver dz

Uric Acid

Crystal: Cystine

colorless, flat hexagons
COMMON in: MALE dachshunds, english bulldogs, newfoundlands, CATS- siamese
from an inherited defect in cystine metabolism

Cystine

What are the COMMON Crystals seen in Dalmations?

uric acid and ammonium biurate

Crystal: Leucine

large, yellow spheres w/ concentric striations
indicate severe liver disease

Leucine

Crystal: Tyrosine

colorless OR yellow needles in groups or alone
IN CLUSTERS = severe liver disease

Tyrosine

Crystal: Sulfonamide

varies in shape and color, haystack-like bundles or rediant spheres
from sulfa drugs

Sulfonamide

Crystal: Calcium Carbonate

varies in size, individual or cluster, yellow-brown, or colorless, large spheroids with radial striations or "dumb bell"
NOT in dogs or cats
COMMON in: horses, rabbits, guinea pigs, and goats (herbivores)

Calcium Carbonate

Casts

formed in lumen of distal and collecting tubules of kidney

Where is the concentration and acidity of urine the greatest in kidneys?

distal and collecting tubules

Formation of Casts

in the renal tubules, secreted proteins in acidic conditions form casts that are made of proteins from plasma and mucoprotein secreted by tubules

What are Casts made of?

protein from plasma and mucoprotein secreted by the tubules

What CAUSES the formation of DIFFERENT Casts to form?

from how quickly the filtrate is moving thru the tubules and how much tubular damage is present

How are Casts Reported?

numbers seen per low-power field (10x) and is classified by type

How many Casts are TYPICALLY seen and what KIND in NORMAL patients?

few-none and hyaline or granular

What does the presence of NUMEROUS Casts indicate?

generalized, acute, renal disease BUT not a reliable indicator

What Urine TYPE do Casts FORM IN?

acidic

What Urine TYPE do Casts DISSOLVE IN?

akaline

Cast: Hyaline

clear, colorless, transparent cylindrical w/ROUNDED sides
made of protein
considered "NORMAL"
seen in: hyperthermia, poor renal perfusion, or other mild kidney irritation

Hyaline

Cast: Cellular

either WBC or RBC
results from: ischemia, infarction, or nephrotoxicity

What does WBCs in Cellular Cast indicate?

inflammation in renal tubules

What does RBCs in Cellular Cast indicate?

renal bleeding

Cellular RBC

Cellular WBC

Cast: Granular

COMMON
a stage in the degeneration of cellular casts
if HIGH #'s = acute nephritis or severe kidney damage

Granular

Cast: Waxy

smooth consistency, refractile, wide, squared off ends, brittle looking
a stage in the CONTINUE degeneration of granular cast
indicate tubular injury MORE severe than cellular or granular casts
ALWAYS pathogenic significance

Waxy

Cast: Fatty

refractile, lipid droplets inside
COMMONLY seen in CATS w/ renal disease

Fatty

Urine: Erythrocytes

small, rounded, smooth-edged, somewhat refractile
SMALLER than WBCs
appearance is affected by: urine concentration, pH, time period of collection and examination

What are the different kinds of RBCs in urine?

intact, crenated, or lysed

Where do RBCs in Urine originate from?

any part of urinary tract that is inflamed or infected

RBCs in acidic or concentrated urine

shrink or crenate

RBCs in alkaline or diluted urine

swell and lyse

What do Hemolyzed RBCs release into the urine?

hemoglobin

How are Erythrocytes Reported?

numbers in average seen per high-power field (40x) and note clumping

Urine: Leukocytes

mainly segmented neutrophils
LARGER than RBCs and SMALLER than epithelial cells
clumps are significant

WBCs in concentrate or acidic urine

shrink

WBCs in alkaline or diluted urine

swell

What do Leukocytes Indicate if Present in the Urine?

pyuria, nephritis, pyelonephritis, urteritis, cystitis, urethritis

Urine: Epithelial Cells

normal for some of these to be present in the urine
HIGH NUMBER = inflammation

What are the Different kinds of Epithelial Cells?

squamous, transitional, and renal

Squamous Epithelial Cells

from the urethra, vagina, or prepuce and found in using the free-catch or catherization method. NOT found in cystocentesis

Squamous

Transitional Epithelial Cells

line the ureters, renal pelvis, bladder, and proximal urethra and will be present in utilizing the catherization method

Transitional

Renal Epithelial Cells

SMALLEST epithelial cell, comes from renal tubules, RARELY found EXCEPT as CASTS`

Order from Largest>Smallest of WBC, RBC, Bacteria, and Epithelial cells

epithelial> WBC> RBC> bacteria

Urine: Bacteria

can be insignificant or important pathogen, but in NORMAL urine is NOT present and in cystocentesis abnormal IF present.

Renal

What is the name for Round Bacteria?

cocci

What is the name for Rod-Shaped Bacteria?

bacilli

How are Bacteria Reported?

few/moderate/many or 1+/2+/3+/4+

Filamentous Mold

Budding Yeast