urine sampling techniques

Question 1

what are the pros and cons of litter tray sampling of urine

Answer 1

pros
- easy
- cheap
- non-invasive
- stress free

cons:
- indoor cats only?
- how old is sample?
- contamination
- multi cat households

Question 2

what are the pros and cons of sampling urine from the floor

Answer 2

pros:
- very easy
- cheap
- non invasive
- stress free

cons:
* how long has the urine been there
* contamination
* multi pet household

Question 3

what are the pros and cons of obtaining a urine sample through bladder expression

Answer 3

pros:
- easy with training
- cheap
- not very invasive
- sample is fresh

cons:
- possibly painful
- can cause trauma
- strong abdominal muscles make it hard
- intestines in there
- could rupture bladder
- contamination from external genetalia
- need a helper and reasonably full bladder
- difficult in large/uncooperative patients

Question 4

how do you place a catheter in a male dog in order to obtain a urine sample

Answer 4

• choose appropriate size catheter (3.5-12fr)
• clip hair, clean penis and flush prepuce
• wear sterile gloves, apply lubricant
• get assistant to extrude penis
• approx length from urethral orifice to pelvic brim
• introduce catheter into urethra in sterile manner
• advance until urine flows
• get mid stream sample
• remove or secure a closed collection system

Question 5

how do you insert a catheter into a male cat

Answer 5

• sedate/GA
• dorsal/lateral recumbency with hind limbs extended cranially
• clip and clean
• sterile glove + lubricant + lidocaine
• extrude penis dorsally and caudally to strighten urethra
• gently advance into urethra util urine flow
• obstructions often at tip
• flushing may aid advancement
• flush bladder/remove/secure

Question 6

how do you insert a catherter into a bitch

Answer 6

• ventral recumbency
• select catheter
• flush vaginal vault with dilute chlorhex
• sterile gloves and lube
• speculum to visualise ventral wall of vagina
• guide catheter in
• advance until urine
• remove or fix and closed system

OR blind:
- feel for urethral papillae at level of pelvic brim
- use finger to guide along ventral wall of vagina and into urethra
- beware blind ending vault

Question 7

what are the pros and cons of obtaining a urine sample via catheter

Answer 7

pros:
- easy in male dogs
- can be diagnostic and therapeutic
- not very invasive
- fresh sample

cons:
- possibly painful
- can cause trauma
- urethra
- bladder
- iatrogenic ascending infections
- sample contamination from lower urinary tract
- may need sedation/GA
- may be difficult in females
- transitional cells (seed tumours)

Question 8

how to perform blind cystocentesis

Answer 8

• select needle 22G 1-1.5 inch and syringe
• lateral or dorsal recumbency
• palpate bladder with non-dominant hand
• slight caudal pressure to isolate
• sterilise site for needle insertion
• insert needlt at 30-45 degree angle aiming caudallt to required depth
• aspirate urine
• stop aspirating and remove needle

Question 9

what are the pros and cons to blind cystocentesis

Answer 9

Pros
* Can be diagnostic and therapeutic
* No Lower urinary tract contamination -culture
* Fresh and immediate sample

Cons
* Possibly painful
* Can cause trauma
* Bladder- possible rupture!
* May hit other organs
* Iatrogenic haematuria
* Requires some operator skill
* May need sedation/ GA
* Difficult in large patients/ small bladder

Question 10

how to perform ultrasound guided cystocentesis

Answer 10

• Clip the area and aseptically prepare.
• Probe midline/ adjacent to penis (3rd and 4th set of nipples)
• Technique as for blind but
• Visualise bladder in longitudinal view on the screen
• Insert needle in line with probe indicator notch (Top picture)
• Aim for bladder neck (Bottom picture)
• See needle enter bladder before aspirate

Question 11

what are the pros and cons of ultrasound guided cystocentesis

Answer 11

Pros
* Can be diagnostic and therapeutic
* No Lower urinary tract contamination -culture
* Fresh and immediate sample
* Safer than blind cystocentesis
* Easier to hit small bladder
* Can gain information on bladder appearance at the same time

Cons
* Possibly painful
* Can cause trauma
* Bladder- possible rupture!
* Iatrogenic haematuria
* Requires operator skill
* May need sedation/ GA
* May need additional helper

Question 12

how should you obtain a sample from an animal with a bladder mass

Answer 12

• DO NOT attempt to sample mass or urine via cysto/transabdo FNA
• most common bladder neoplasia = transitional cell carcinoma
• can seed into abdomen if transabdominal needle sampling
• instead: endoscopy, cytoscopy or visualise and sample or image via ultrasound and use urinary catheter to sample urine and cells via urethra

Question 13

what should you ask when you receive a urine sample from a client

Answer 13

• container: washed properly?
• fresh sample?
• how was it obtained
• when was it taken
• was it refridgerated

Question 14

when might you want to use an EDTA tube for a urine sample

Answer 14

prevents degradation of cellular components

Question 15

what values on a urine dipstick shoule be disregarded in dogs and cats

Answer 15

• leukocytes
• nitrites
• urobilinogen
• specific gravity

Question 16

what should we check on a urine dip stick test

Answer 16

• comparison strip (control)
• blood (speckled if bloody)
• bilirubin cats should be neg, up to 2+ can be normal in dogs
• ketones (only acetoacetate)
• glucose (normal = neg)
• protein (normal = neg)
• pH (6-7 = norm)

Question 17

what does USG measure

Answer 17

weight of a given volume of liquid compared to same volume of distilled water
- healthy hydrated animals can have any USG but typically dogs = 1.015-1.045 cats = 1.035-1.060
- if clinically dehydrated, dogs = > 1.030 cats = > 1.035

Question 18

what is hyposthenuria

Answer 18

1.001-1.007 USG < plasma SG. actively diluting

Question 19

what is isosthenuria

Answer 19

1.008-1.012 USG = plasma SG, neither concentrating or diluting

Question 20

what is hypersthenuria

Answer 20

1.013 - > 1.075 USG > plasma SG actively concentrating to some degree

Question 21

explain the steps to looking at urine under microscope

Answer 21

• Agitate urine
• Decant even samples into 2 conical sample pots
• Place in centrifuge in opposing spaces
• Spin at 1000-1500rpm for 3-5mins
• Remove from centrifuge without agitating
• Remove supernatant leaving pellet at the bottom undisturbed
• Resuspend pellet in remaining urine by agitating

Sediment stains
* Add one drop of Sedi stain to the container and mix add one drop to a slide cover with a coverslip and view
* Good for cell details but contaminants/artefacts
* consider air drying and Diff-Quick instead?

Plain slides
* Place 1 drop if sediment rich plain urine on slide
* Cover with coverslip and observe

Question 22

what might you see on urine microscopy

Answer 22

• hematuria (up to 5 RBCs and 5 WBC per HPF = normal)
• transitional cells
• squamous cells from urethra and female genital tract
• renal tubular cells –> look like WBCs/small transitional cells but could indicate tubular damage
• casts (moulds of renal tubules, less than 2 hyaline and 1 granular is normal per LPF but more than that = damage of tubes)
• crystals
• lipid droplets
• pathogens (fungi/yeast/bacteria, with accompanying WBC if not contamination)

Question 23

what is a cast

Answer 23

• mould of the renal tubules
• mucoproteins +/- cells
• more likely if low pH / low urine flow rate / high USG
• less than 2 hyaline and 1 granular shoulr be visible per low power field
• more indicate tubular damage

Question 24

what kind of crystal is this and is it normal

Answer 24

calcium oxalate dihydrate
- normal. also seen as artifact of storage

Question 25

what kind of crystal is this and is it normal

Answer 25

struvite - seen in cases of altered pH (UTI)

Question 26

what kind of crystal is this

Answer 26

bilirubin seen in liver disease

Question 27

what kind of crystal is this

Answer 27

ammonium bi-urate

Question 28

what kinds of crystal is this

Answer 28

calcium oxalate monohydrate seen due to toxin or drugs