12c. Urinalysis: Sediment Examination Flashcards
How is urine sediment examined?
a microscopic exam performed on a centrifuged sample
sediment exam is used to look for cells, casts, bacteria, crystals, etc
Microscopic examination complements the urine test strip
sediment exam is best method for performing a preliminary screen for the presence of bacteria
used to confirm the presence of RBC’s and WBCs
it is hugely limited by user’s technical abilities
What is the best option for assessing the lower urogenital tract?
free-catch, first morning sample
What is the best option to assess for the presence of bacteria in the bladder or kidney
cystosentesis
How should samples be stored?
stored in frige if not evaled within 1hr
store at room temp may result in bacterial overgrowth
store in fridge may cause crystal artifacts
casts may dissolve alkaline urine
How should a urine sample be collected for a sediment exam?
collect 30-10mL of urine and place it in a labelled centrifuge tube
text recommends using 10mL of urine, often only require 3-5mL from small animal patients; either volume is acceptable but be consistent
What should we remember to set aside in the event that a urine culture is required?
a small “sterile” sample (0.5cc at least)
How should a urine sample be centrifuged for urine sediment
make sure sample is balanced in the centrifuge
centrifuge @ 1000-2000RPM for 3-6 minutes
allow centrifuge to stop on its own
decant supernatant leaving 0.5-1.0mL of urine in the tube (pour decant into a separate container if the chemical analysis has not been performed)
Once a sediment sample has been centrifuged, what should we do in the preparation process?
re-suspend sediment by flicking tube or by drawing sample up/down w/ a pipette
place 1 drop of urine on slide and add cover slip
let slide sit for 30-60 seconds
scan with the entire slide on 10x objective to look for large formed elements like casts and cluster of cells
Once we’ve examined the slide on 10x objective, what do we do?
move to high dry 40x objective
ID following unstained urine (presence may be confirmed in stained urine)
WBCs, RBC, fat droplets, bacteria, crystals, transitional and epithelia cells, debris/other
look at min. 10 fields and record result
Ex. WBC 5-10/hpf OR WBC 8/hpf
How is bacteria recorded when recording results?
bact may be reported as few, mod, or mny OR by # range that is present/hpf (can be reported as TNTC)
bact crystals may also be reported on 1+ to 4+ scale
Give morphological description of any bacteria that are noted (cocci, rods, single, diploid, chains, clumps)
What do you record when bacteria is few, mod, many or TNTC in %?
Few: <5% of the field is occupied
Moderate: 5-25%
Many: 25-75%
TNTC: >75%
What do you record if you see sperm and mucus?
Present
What is the advantage of staining with sedi-stain?
highlights cells so that it is easier to identify the cell type
fat droplets do not stain
What is the disadvantage of staining with sedi-stain?
often contaminated so may result in falsely elevated bacterial counts
stain sediment can be easily confused with crystals - can remove stain sediment by filtering stain weekly
quantification of elements MUST be done on the same unstained slide as the stain will dilute the sample
How do we stain a sample?
NEVER add stain directly to collection tube
Add 1 drop urine + 1 drop stain to slide then cover slip OR add one drop stain to ege of coverslip after viewing the unstained urine
In terms of sediment, what is the normal for cat/dog? What might you see instead?
Very little to no sediment
May have sm #’s of sperm, epithelia cells, RBCs and WBCs depending on the method of collection and neuter status
may have fat droplets, mucus threads, hyaline casts and struvite/amorphous crystals
In terms of sediment, what might you find in an equine/rabbit. What might you find instead?
can have significant amount - bc of lg #s of calcium carbonate crystals in healthy animals
What are the types of cells you might find in urine?
Squamous and transitional epithelial cells, renal epithelial cells, RBCs, WBCs, influenced by collection method used
Cysto +/- squamous, transitional epithelial +/-, RBC +/-, WBC X
Catheter: + squamous, ++ transitional, ++ RBC, WBC X
Free catch: + squamous, X transitional, X RBC, +/- WBC
Why might we find RBCs in the urine? What is the presence of it called
Hematuria. Usually indicates hemorrhage of urogenital tract
Can be caused by inflam, infection, trauma, calculi, strenuous exercise, neoplasia, estrus, clotting/bleeding disorder, severe renal dz
Can be contam due to cystocentesis, manual expression or rough catheterization
usually corresponds with increased protein lvl on dipstick
What do RBCs look like in the urine?
cells appear pale reddish brown to yellow color with a paler center
In fresh sample, uniform in size/shap (round and smooth)
often created in concentrated urine or sample that has sat for a period of time
can be confused w/ fat globules or yeast
What do fat globules look like in urine?
significant variation in size, sit of diff plane, refract light, and do not take up stain
What could WBCs in the urine indicate?
inflam, infection, trauma, or peripheral blood contamination - may be present in sm #’s in free catch samples due to contamination from the lower urogenital tract
>2-3/hpf is abnormal - blood contamination needs to be taken into consideration
What do WBCs look like in urine?
WBC uniformly round cells, slightly lger than RBCs but smaller than renal epithelial cells
can have slight grey or greenish-yellow color
they often have granules in cytoplasm and will have lobulated nucleus (most WBC present in urine are neutrophils)
cellular features are highlighted w/ stain
What is one way to tell if WBCs in the urine is inflammation or blood contamination?
There will be equal or more WBCs than RBCs, which indicates inflam
What does increased numbers in the urine of WBCs called?
Pyuria (pus in the urine).
WBC may be found alone or in clumps
What could pyuria indicate?
A bact UTI, even if bact are not visible on sediment exam - indication to culture
What is an acceptable amount of epithelial cells in the urine?
acceptable # depends on the method of collection used
a marked increase in numbers usually indicates inflam
What are the 3 diff types of epithelial cells in the urine
Squamous, transitional, and renal