urine sampling techniques Flashcards
what are the pros and cons of litter tray sampling of urine
pros
- easy
- cheap
- non-invasive
- stress free
cons:
- indoor cats only?
- how old is sample?
- contamination
- multi cat households
what are the pros and cons of sampling urine from the floor
pros:
- very easy
- cheap
- non invasive
- stress free
cons:
* how long has the urine been there
* contamination
* multi pet household
what are the pros and cons of obtaining a urine sample through bladder expression
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
how do you place a catheter in a male dog in order to obtain a urine sample
- 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
how do you insert a catheter into a male cat
- 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
how do you insert a catherter into a bitch
- 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
what are the pros and cons of obtaining a urine sample via catheter
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)
how to perform blind cystocentesis
- 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
what are the pros and cons to blind cystocentesis
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
how to perform ultrasound guided cystocentesis
- 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
what are the pros and cons of ultrasound guided cystocentesis
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
how should you obtain a sample from an animal with a bladder mass
- 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
what should you ask when you receive a urine sample from a client
- container: washed properly?
- fresh sample?
- how was it obtained
- when was it taken
- was it refridgerated
when might you want to use an EDTA tube for a urine sample
prevents degradation of cellular components
what values on a urine dipstick shoule be disregarded in dogs and cats
- leukocytes
- nitrites
- urobilinogen
- specific gravity
what should we check on a urine dip stick test
- 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)
explain the steps to looking at urine under microscope
- 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
what is a cast
- 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
what kind of crystal is this and is it normal
calcium oxalate dihydrate
- normal. also seen as artifact of storage
what kind of crystal is this and is it normal
struvite
- seen in cases of altered pH (UTI)
what kind of crystal is this
bilirubin
seen in liver disease
what kind of crystal is this
ammonium bi-urate
what kinds of crystal is this
calcium oxalate monohydrate
seen due to toxin or drugs
