Urine sediment evaluation

Question 1

Why look for urine sediment

Answer 1

A microscopic examination is performed on a centrifuged sample
The sediment exam is used to look for cells, casts, bacteria crystals, etc
Microscopic examination complements the urine test strip
Sediment exam is the best method for performing a preliminary screen for the presence of bacteria
It is used to confirm the presence of RBCs and WBCs
It is hugely limited by the users technical abilities

Question 2

What type of collection would you use for urine sedimentation

Answer 2

A freecatch sample is the best option for assessing the lower urogenital tract
First morning sample preferred
Cystocentesis is the best option to asses for the presence of bacteria in the bladder or kidneys

Question 3

What should you do with urine after collected and why

Answer 3

The sample should be assessed right away
The sample should be stored in the fridge if it will not be evaluated within one hour of collection
Storage at room temp may result in bacterial overgrowth
Storage in the fridge may cause crystal artifacts
Casts may dissolve in alkaline urine

Question 4

How much urine should you collect

Answer 4

Collect 3-10mL of urine and place it in a labelled centrifuge tube
The text recommends using 10mL of urine→ we often only acquire 3-5mL from SA patients; either volume is acceptable, but be consistent
Remember: always set aside small “sterile” sample (0.5cc at least) in the event that a urine culture is required

Question 5

What to do to look at urine sedimentation

Answer 5

Centrifuge the sample
Make sure sample is balanced in the centrifuge
Centrifuge at 100-2000 RPM for 3-6 minutes
Use “urine setting” if available
Allow centrifuge to stop on its own
You may see a small pellet at the bottom of the tube
Decant supernatant leaving 0.5-1mL of urine in the tube
Pur the decant into a separate container if the chemical analysis has not yet been performed
Re-suspended sediment by flicking the tube or by gently drawing the sample up and down with a pipette
Place on drop of urine on a slide and add the cover slip
Optional- stain can also be added to the slide at thai time
Let slide sit for 30-60 sec
Scan with the entire slide on 10x objective to look for large formed elements like casts and clusters of cells
Move to high dry (40x objective)

Question 6

What should you look for on high dry for urine

Answer 6

Identify the following with unstained urine (presence may be confirmed in stained urine)
RBC
WBC
Fat droplets
Bacteria
Crystals
Epithelial cells
Transitional cells
Debris/other
Look at a minimum of 10 fields of view under high power and record your results

Question 7

What should you record on a urine sediment evaluation

Answer 7

Record the average number of casts and crystals per low power field (lpf)
Record the average number of all other cellular elements per high power field (hpf)
Bacteria
Sperm and mucus are only reported as being present

Question 8

How to record cellular elements in urine

Answer 8

The number of RBCs, WBCs and epithelial cells present can be reported as an average number per 10 hpfs OR as a range of the number present in the fields examined

Question 9

How to quantify bacteria in urine

Answer 9

Few: <5% of the filed os occupied
Moderate: 5-25% of the field is occupied
Many: 25-75% of the field is occupied
TNTC: >75% of the field os occupied

Question 10

How to describe bacteria and crystals in urine

Answer 10

Bacteria may be reported as few, moderate, or many OR by the number range that is present/hpf (can also be reported as TNTC)
Bacteria and crystals may also be reported on the 1+ to 4+ scale
Give morphological description of any bacteria that are noted (cocci, rods, single, diploid, chains, clumps)

Question 11

What stain is comonly used on urine

Answer 11

Sedi-stain

Question 12

Advantages of sedi-stain

Answer 12

Highlights cells so that it is easier to identify the cell type
Fat droplets do not stain

Question 13

Disadvantages of sedi-stain

Answer 13

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 unstained slide as the stain will dilute the sample
Never add the stain directly to the collection tube

Question 14

How to use sedi-stain on urine

Answer 14

Never add the stain directly to the collection tube
To stain
Add 1 drop urine+1 drop stian to slide, then coverslip
OR
Add one drop stain to edge of coverslip after viewing the unstained urine

Question 15

Normal sediment in cat and dog urine is

Answer 15

Normal cat/dog urine has very little to no sediment
May have small numbers of sperm, epithelial 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

Question 16

Normal sediment in equine and rabbit urine

Answer 16

Normal equine and rabbit urine can have a significant amount of sediment
This is due to large numbers of calcium carbonate crystals in healthy animals

Question 17

Types of cells found inurine

Answer 17

Squamous epithelial cells
Transitional epithelial cells
Renal epithelial cells
RBCs
WBCs
Influenced by the collection method used

Question 18

Common cells in free catch urine

Answer 18

squamous epithelial
sometimes WBC

Question 19

common cells in catheter samples

Answer 19

squamous and transitional epithelial
RBC

Question 20

Common cells found in cysto urine

Answer 20

sometimes Squamous and transitional epithelial
sometimes RBCs

Question 21

Hematuria is

Answer 21

present of blood in urine

Question 22

RBC in urine can indicate

Answer 22

Usually indicates haemorrhage of the urogenital tract

Question 23

Causes of hematuria

Answer 23

Inflammation, infection, trauma, calculi, strenuous exercise, neoplasia, estrus, clotting/breeding disorder, severe renal disease

Question 24

What can cause contamination hematuria

Answer 24

Can be contaminated due to cystocentesis, manual expression, or rough catheterization

Question 25

What are common signs of hematuria

Answer 25

Usually corresponds with increase protein level on the dipstick Cells appear as pale reddish brown to yellow colour with paler centre Is fresh sample they will be uniform in size and shape (round and smooth) Often crenated in concentrated urine or a sample that has sat for a period of time Can be confused with fat globules or yeast Fat globules have significant variation in size, sit on a different plane, refract light, and do not take up stain

Question 26

Whit blood cells in urine is caused by

Answer 26

Indicates inflammation, infection, trauma, or peripheral blood contamination May be present in small numbers in free catch samples due to contamination from the lower urogenital tract

Question 27

When is WBCs in urine abnormal

Answer 27

>2-3/hpf is abnormal- blood contaminations needs to be taken into consideration

Question 28

What do WBCs in urine look like

Answer 28

WBC are uniformly round cells, slightly larger than RBCs but smaller than renal epithelial cells Can have a slight grey to greenish-yellow colour They often have granules in the cytoplasm and will have a lobulated nucleus Most WBC present in urine are neutrophils Cellular features are heightened with stain May be found alone or in clumps

Question 29

Pyuria is and can indicate

Answer 29

Increased numbers of WBCs in the urine are called pyuria Pyuria can indicate a bacterial UTI even if bacteria are not visible on the sediment exam Indication to culture

Question 30

Are epithelial cells in urine normal and what will their presence increase

Answer 30

A few are normal in a urine sample The acceptable number depends on the method of collection used A marked increase in number usually indicates inflammation Their presence will increase the protein level reading on the urine test strip

Question 31

What are the 2 types of epithelial cells that can be present in urine

Answer 31

Squamous epithelial cells Transitional epithelial cells Renal epithelial cells

Question 32

Squamous epithelial cells located where and look like

Answer 32

Located in the distal urethra, vagina, vulva and prepuce Most commonly observed in free catch samples Seldom present if a cystocentesis is performed Very large, flat, thin, irregularly shaped Easily fold over on themselves Small centrally placed nuclei Abundant cytoplasm

Question 33

Transitional epithelial cells look like and located where

Answer 33

Line the bladder, ureters, renal pelvis and proximal urethra 2-4 times larger than WBC They are round to pear-shaped and have abundant granular cytoplasm They will have a small nucleus that is centrally located May be found in clumps 0-1/hpf are normal in health May be increased in samples collected by catheterization Increased numbers may indicate cystitis or pyelonephritis

Question 34

Renal epithelial cells are and look like

Answer 34

The smallest epithelial cells in urine Only slightly larger than WBCs Often confused with WBCs Originate in the renal tubules They are round with a central, large, round nucleus The cytoplasm may be agranular or may contain fine granules If >1/hpf are present, there is likely disease of the renal parenchymal tissue

Question 35

Neoplastic cells are

Answer 35

Any cells that contain more than one nucleoli, have multiple nuclei/cell, mitotic figure, variations in cell size, variations in the size of the nuclei, have inclusions, or appear in large clumps should be brought to the vets attention Samples are often sent to a pathologist for identification May request follow up testing such as ultrasound or traumatic catheterization

Question 36

Urine casts look like and are composed of

Answer 36

Cylindrically shaped structures with parallel sides Ends may be tapered, irregular or round Composed of mucoprotein May also contain trapped cells and other debris Formed within the renal tubules

Question 37

How do urine casts diffenrtiate

Answer 37

Casts differentiated based on their composition and appearance Hyaline Granular Epithelial Cellular (contains RBC, WBC, or both) Waxy Fatty Mixed

Question 38

When do urine casts dissolve

Answer 38

Casts dissolve in alkaline urine Urine should be examined promptly to prevent false negative results

Question 39

How to look at urine casts

Answer 39

View with 10X objective to start: move to 40X objective to determine type 0-1 hyaline or granular casts/lpf in concentrated urine may be reported in normal animals Higher numbers indicate renal tubular injury Any type of cast can be stained with bilirubin (yellow-brown colour) when there is excess amounts of bilirubin in the urine Casts may also contain various crystal types

Question 40

Hyaline casts are

Answer 40

One of the most common types of casts Clear, colourless and somewhat transparent Do not contain inclusions Cylindrical with parallel sides and rounded ends Made of protein

Question 41

How to look at hyaline casts and when are they elevated

Answer 41

Easily missed; adjust your condenser and fine focus Easier to identify in strained than unstrained samples They do nor necessarily indicate kidney disease Low numbers (0-1/lpf) may be normal Elevated numbers will be seen with mild renal irritation, fever, decreased renal perfusion, GA or strenuous exercise

Question 42

Granular casts are and look like

Answer 42

The most common type of casts seen in animals They are hyaline casts that contain granules The granules are tubular epithelial cells, RBC, or WBC that become incorporated into the casts and then degenerate Casts can be classified as course or fine granular casts

Question 43

What does large number of urine granular casts indicate

Answer 43

Large numbers indicate more severe kidney damage than if just hyaline casts are observed Acute nephritis As the course granular casts ages, it becomes a fine granular cast

Question 44

Urine epithelial casts are

Answer 44

A hyaline cast that has entrapped renal epithelial cells within its matrix Seen with degenerative renal tubular diseases and acute nephritis which results in epithelial cell sloughing

Question 45

Cellular- leukocyte casts in urine are and look like

Answer 45

These casts contain WBCs- mostly neutrophils Indicates inflammation of the renal tubules

Question 46

Cellular- erythrocyte casts in urine look like and indicate

Answer 46

RBC casts will have a yellow to orange colour RBC membranes may or may not be visible Indicates renal haemorrhage Trauma disorders or inflammation

Question 47

Waxy casts in urine look like and indicate

Answer 47

Resemble hyaline casts Usually wider, with square ends, instead of rounded ones Are gray to colourless and have a dull waxy appearance They are usually highly refractile Indicate severe and chronic renal tubular degeneration Waxy casts are easily missed unless you have your condenser low and adjust the fine focus of your microscope

Question 48

Fatty casts in urine look like and indicate

Answer 48

Contain many small droplets of fat They have small refractile bodies in the cast Common in dogs with renal disease, and dogs with diabetes mellitus Large numbers will be seen with renal tubular degeneration

Question 49

Crystals in urine is called and where is it found

Answer 49

Crystalluria- the presence of crystals in the urine Found in both normal and abnormal urine Different types of crystals have different chemical make-ups

Question 50

Crystal type depends on and how to ID

Answer 50

The pH of the urine Genetics Identification is based on the shape of the crystal

Question 51

Factors that increase crystal formation

Answer 51

Certain diets Urine concentration (higher USG → more crystals) Temp (cold→ more crystals) Alkaline urine Urinary tract infection in dogs

Question 52

Stuvite crystals are

Answer 52

AKA triple phosphate crystals AKA magnesium ammonium phosphate (MAP) crystals Increased formation in alkaline urine (pH 7.0 and up) Often associated with urease producing bacterial UTIs Small numbers can be normal in dogs and cats Are clinically significant when they are in large numbers and are accompanied by clinical signs

Question 53

Struvite crystals look like and are dissolved by

Answer 53

Prism of coffin-lid shape and will have the “Y” formation Can form if urine left to sit for long periods Struvite crystals can be dissolved with diet Can be small to very large

Question 54

Calcium oxalate crystals in urine two forms

Answer 54

2 forms Clinically important to specify which type is present Calcium oxalate dihydrate Square with “x” Calcium oxalate monohydrate Various shapes Ethylene glycol toxicity

Question 55

Calcium oxalate dihydrate crystals in urine look like

Answer 55

Appear as small boxes with “X” across the crystal Looks like the back of an envelope Can vary in size though tend to be smaller than struvite crystals

Question 56

Calcium oxalate dihydrate are found where in urine

Answer 56

Found in urine with an acidic or neutral pH Small numbers are normal in horses, cattle and other herbivores In dogs May be an incidental finding if present in small numbers Clinically significant if large numbers are present Risk factors: a diet high in calcium and/or oxalate: genetics

Question 57

Calcium oxalate monohydrate look like

Answer 57

Usually small, bumb-bell shaped crystals Less commonly round disks, or enlarged and pointed like a picket fence Most commonly seen with ethylene glycol toxicity

Question 58

Urate crystals look like and are common in

Answer 58

Uric acid crystals Usually diamond or rhomboid shaped crystals Yellow to yellow-brown in colour Commonly found in Dalmations Otherwise rare in dogs and cats

Question 59

Amorphous crystals in urine are found in and look like

Answer 59

Amorphous phosphate crystals are found in alkaline urine Amorphous urates look very similar to amorphous phosphate crystals but are found in acidic urine Are colourless, granular precipitate Can be artefact from cooling the urine

Question 60

Calcium carbonate crystals are and look like

Answer 60

Common in horses and rabbits Have a variety of forms Dumb-bell shaped Striated spheres Clover leaf shape Found in neutral to alkaline urine Very rare in dogs and cats No clinical significance

Question 61

Ammonium biurate crystals are found in and look like

Answer 61

Found in slightly acidic, neutral or alkaline urine Brown in colour They crystals have a round shape with long irregular spicules Have been called “thorn apple crystals” Associated with liver disease (portosystemic shunts)

Question 62

Crystals: sulphonamide look like and are common in

Answer 62

Patients being treated with sulfonamides will often have these types of crystals present in their urine Check the patient history Individual crystals radiating out from the center Dark in appearance

Question 63

Crystals: bilirubin look like and indicates

Answer 63

Pigmented, golden-brown feather-like appearance Found in acidic urine Represents an increased urinary concentration of bilirubin May indicate cholestatic liver disease or hemolytic anemia

Question 64

Crystals: cystine look like and are associated with

Answer 64

Appear to be flat or thin 6 sided (hexagonal) Colourless Associated with renal tubular dysfunction or cystine urolithiasis

Question 65

Microorganisms are common in urine when

Answer 65

Bacteria, fungi, and protozoa may be found in urine Organisms are not found in healthy urine when collected by catheterization or cystocentesis May be found in free catch samples as contaminants from the genital tract and surrounding skin/fur Will replicate if left at room temp Refrigerate sample if analysis will not occur in the first 60 min

Question 66

How to look at bacteria in urine and report it

Answer 66

Identify 40x objective Report morphology: cocci, rods Give arrangement: single, diploid, short chains, occasionally tetrad Look for motility Differentiate from Brownian movement Give number: few, moderate, many, TNTC; when possible, give average #/hpf or range/hpf

Question 67

Bacteria in urine can indicate

Answer 67

The presence of bacteria alone DOES NOT indicate a urinary tract infection with free catch samples Normally there will be increase in WBCs and some RBCs when there is a UTI, pyelonephritis, prostatitis or a pyometra Bacteria are most significant when they are found within WBCs A cystocentesis sample is the preferred collection method when a UTI is suspected or a urine culture is required

Question 68

Yeast in urine looks like and is an indicator of

Answer 68

Often confused with RBCs or fat droplets Will have characteristic budding and double refractile walls They are usually a contaminant Can be from a dermal yeast infection if it is a free catch sample

Question 69

Fungi in urine is caused by

Answer 69

Rarely found in urine, but when they are, it can be very serious Can be contaminant from the environment when collected as a free catch sample They are filamentous and usually branching

Question 70

Parasites in urine are caused by

Answer 70

Can be from faecal contamination or parasites of the urinary tract

Question 71

The following parasites can all be found in urine

Answer 71

Pearsonema plica- bladder worm (dogs and cats) Dirofilaria immitis Dioctophyma renale- kidney worm (dogs)

Question 72

Mucus threads in urine look like

Answer 72

Can be confused with casts Edges are not as well defined as in casts Resembles a twisted ribbon Prevalent in equine urine In other animals it indicates urethral irritation or contamination from genital secretions

Question 73

Spermatozoa in urine is caused by

Answer 73

Seen in the urine of intact males or recently bred females No clinical significance May cause an increase in protein levels in the urine test strip

Question 74

Fat droplets in urine are caused by and look like

Answer 74

Very common Highly refractile, spherical bodies that vary in size If you let your slide sit for 1 minute, the fat droplets will rise to the top of the drop of urine and not be in the same field of view as the other elements Not clinically significant

Question 75

Artefacts in urine can look like

Answer 75

These are of little significance and are commonly found in urine collected from dusty environments or in tall dry grasses Includes Air bubbles Hair Fecal material Plant spores, pollen or other plant material Fibres Dust Starch granules - from gloves Glass fragments from the coverslips or slides

Question 76

Normal urine results

Answer 76

0-3 RBC/hpf – largely dependent on collection method 0-3 WBC/hpf Few epithelial cells/hpf (more in samples collected by catheterization) 0-1 hyaline or granular casts/lpf in concentrated urine Fat droplets are common in dog/cat urine Spermatozoa in intact males or recently bred females Bacteria in small numbers when urine collected by free-catch or with poor catheterization technique Small numbers of crystals (struvite and/or calcium oxalate dihydrate) in cats and dogs Calcium carbonate and calcium oxalate dihydrate crystals in horses Mucus strands in equine urine Environmental contaminants/artifacts

Question 77

Abnormal urine results

Answer 77

>3 RBC/hpf > 3 WBC/hpf Casts ->0-1/lpf –hyaline or granular casts -The presence of any cast other than hyalin or granular Large numbers of crystals or the appearance of unexpected crystal types Parasite ova and microfilaria Bacteria in cystocentesis samples Phagocytosed bacteria Large numbers of yeast or hyphae (watch for contamination) Increased numbers of epithelial cells or abnormal epithelial cells

Question 78

Line preparation for urine is

Answer 78

Place a drop of urine sediment on a slide, take another slide and prepare a smear like you would for hematology BUt, half-way through, lift the spreader slide off the bottom slide Creates a line of concentrated cellular elements on the slide Air dry completely Strain as you would for a blood smear Examine under oil immersion lens Best for identifying cells and bacteria