Clinical techniques Flashcards
What are the 2 broad types of radiography used in urology?
Plain (survey)
Contrast
What are the benefits of a contrast radiograph over a plain?
Gives more detail
What are the key points in radiography in urology?
- Need to radiograph whole abdomen
- Usually in VD (everything spreads)
- Starve 24 hous (faeces/urine obsscure view)
- GA or sedation
- Positioning, centring and collimation important
What is the correct positioning, centring and collimation to take a radiograph of the abdomen?
- VD, avoiding axial rotation using cradle for example
- centre on caudal border of last rib
- collimate to greater trochanter, spine and skin edges
What is meant by positive contrast agents? Give examples
- Appear more radiopaque than surrounding body tissues
- High atomic number e.g. barium or iodine
What is meant by negative contrast agents? Give examples
- Appear more radiolucent than surrounding body tissues
- Gases e.g. air or CO2
What types of radiography can be used to visualise the urethra?
- Plain
- Retrograde ureothrography - contrast (males)
- Retrograde vaginourethrography - contrast (females)
- Plain will only show if abnormal
List the types of contrast radiography that are used in urology
- Intravenous urography (IVU)
- Retrograde vaginourethrogram
- Retrograde cystogram
- Retrograde urethrogram
What are the benefits of an intravenous urography?
- Provides anatomical and functional info about kidneys
- Specific information obtained at each stage of IVU
What are some of the contraindications for an IVU?
- Dehydration/hypovolaemia
- Severe renal failure/anuria
What are the 2 techniques used for IVU?
- High concentration/low volume (inject bolus into peripheral vein)
- Low concentration/high volume (contrast given in IV drip)
Describe the technique for a retrograde vaginourethrogram
- Foley catheter or urinary catheter plus clamp
- Inject diluted iodine contrast media (careful to avoid vaginal rupture)
- Lateral views most helpful, VD maybe for some abnormalities
- Contrast into vagina via catheter, flows inot urethra
Describe the techniue for a retrograde cystogram
- Survey films lateral and VD
- Catheterise, empty, flush bladder
- Inject contrast medium until bladder just turgid (2 day old party balloon)
- Negative, positive or double contrast
What are the benefits and indications for use of negative contrast radiography?
- Cheap, readily available
- Useful to identify bladder, show position and wall thickness
- Poor mucosal detail, may miss small tears
What is the indication for use of positive contrast radiography?
- Suspected bladder rupture
- Expensive, need a lot
What is a double contrast cystogram and what are the benefits?
- Uses negative and positive contrast agents
- Excellent detail
- Useful contrast to see radiolucent calculi for example
Describe the technique for a retrograde urethrogram
- Catheterise urethra (widest possible)
- Position tip distal to area under investigation
- Clamp sheath tightly around catheter
- Inject diluted water soluble contrast medium
- Mix with gel, keeps distension of urethra long enough to take radiograph
- Exposure immediately after end of injection
- Lateral most helpful
What imaging modalities can be used in urology?
- Radiography
- Ultrasonography
- CT
- Endoscopy
What views of the kidney can be achieved with ultrasonography?
- Sagittal
- Transverse
- Frontal (dorsal)
Describe the ultrasonographic appearance of the renal cortex
- evenly granular
- Hypoechoic (occasionally isoechoic) to the liver in dogs
- Often more echogenic in cats
Describe the ultrasonographic appearance of the renal medulla
- Hypoechoic to cortex
- Look for good “cortico-medullary” definition
- Should be able to distinguish the cortex and medulla
Describe the ultrasonographic appearance of the renal pelvis
- Echogenic peripelvic fat (hyperechoic)
What are the 3 layers of the bladder visible on ultrasonography?
- Inner mucosal interface
- Muscle layer
- Outer serosal layer
What is the echogenicity of the inner mucosal interface of the bladder?
Hyperechoic
What is the echogenicity of the muscle layer of the bladder?
Hypoechoic
What is the echogenicity of the outer serosal layer of the bladder?
Hyperechoic
What ultrasonographically identifiable changes will occur in the a bladder with cystitis?
Lots of variation in thickness of the bladder wall
What are some of the disadvantages of radiogaphy in urology?
- In VD get superimposition of spine and prepuce (bladder harder to see)
- ureters and urethra not visible on plain radiograph
What are some of the advantages of ultrasonography in urology?
- Simple, safe, cheap, avoids risks of ionising radiation
- Best imaging technique for kidneys and bladder
What are the “phases” of intravenous urography?
- Angiogram phase
- Nephrogram phase
- Pyelogram phase
Describe the angiogram phase of intravenous urography
- Immediately after introduction of contrast
- All contrast in blood vessles
- Very quick, easily missed
Describe the nephrogram phase of intravenous urography
- Rapid filtration by glomeruli into renal tubules
- Parenchyma of kidney visible
- May still see contrast in blood vessles
Describe the pyelogram phase of intravenous urography
- hrough tubules intro renal pelvis, down to ureter
- See cortex and medulla, into renal diverticuli and pelvis
- Small well defined diverticuli may be seen
- Ureters visible
- On lateral can see ureters into bladder and most of ureters
What types of endoscopic examination can be used for the lower urinary tract?
- Urethroscopy (urethra)
- Cystoscopy (bladder)
- Transurethral cystoscopy
- Prepubic percutaneous cystoscopy
How is a prepubic percutaneous cystoscopy carried out?
Puncture through skin using trochars
List the equipment needed for endoscopy of the lower urinary tract
- Rigid or semi-rigid endoscope with sheath (bitches and some cats)
- Flexible endoscopes (male dogs/cats)
- Camera and light source
- Fluid irrigation
- Instrumentation
- Baskets (sometimes used to collect bladder or urethral stones)
Describe the normal endoscopic appearance of the bladder
- Thin wall when distended
- Can see blood vessels easily
- Translucent wall
Describe what may be seen on endoscopy if there is cystitis
- Opaque, matte appearance suggesting inflammation
- Thickening and inflammation (rubor) visible
List the methods for obtaining urine samples in small animals
- Micturition
- Cystocentesis
- Catheterisation
- ## Midstream Sample Urine (MSSU) - naturally voided or manual expression
What is the main aim when taking a urine sample?
To obtain a urine sample with in vitro characteristics similar to the original urine (in vivo)
What are the advantages of MSSU?
- Easy
- Can be left to the owner if dog voids naturally
- Non-traumatic
- Use of modified litter tray with glass beads can be used for initial screening of cats
What are the disadvantages of MSSU?
- Cats often fussy about litter
- Risk of damage to mucosa in manual expression
- Need to avoid residue at end of urination (bacteriology)
- Risk of haematuria and bladder rupture with manual expression
- Variable volume
- Risk of faecal contamination
- Need decent volume in urine in bladder, too little and get sediment
- Blocked urethra -> ruptured bladder
What are the advantages of cystocentesis?
- Quick, no need to wait for spontaneous urination
- Aseptic collection with no urethral contamination
- Easy to perform when bladder moderately distended and patient restrained
- Lower risk of iatrogenic haematuria
- Also to decompress severely distended bladder
What are the disadvantages of cystocentesis?
- Experience required
- Need adequate volume of urine in bladder
- Iatrogenic micro/macroscopic haemorrhage possible
- Contraindicated if bladder severely diseased or clotting problems
What are the advantages of urethral catheterisation?
- No need to wait for spontaneous micturition
- Relatively free of risk of bacterial contamination
- Ample sample volume
What are the disadvantages of urethral catheterisation?
- Some experience needed
- May need speculum/light source for bitch
- Risk of iatrogenic infection, haematuria +/- mucosal damage
- Cost of equipment and disposable catheter
Outline the technique for obtaining a Midstream Sample of Urine (MSSU)
- Naturally voided or manual
- Manual compress bladder to induce micturition reflex
- Direct compression towards neck of bladder
- Increase pressure to stimulate urination, not squeezing urine out
- Maintain continuous moderate pressure
- Avoid excessive or vigorous intermittent pressure
Describe the technique for urethral catheterisation in the bitch
- Keep catheter in sterile sleeve
- Either direct visualisation of urethral opening with speculum and light source into vulva
- or digital palpation: ventral to vagina palpate urethral hillock, insert catheter ventral to finger
Describe the technique for urethral catheterisation in the queen
- Blind insertion
- Get body as straight as possible
- Cat in sternal, hindlegs to side, parallel
- Advance catheter along ventral vaginal wall along midline, should slip into urethra
Outline the technique of cystocentesis in the dog
- Through abdominal wall into bladder
- Palpate bladder, push against pubis to avoid piercing other organs
- Insert needle into middle of bladder as bladder emptying may cause needle to slip out
- Insert at oblique (45deg) angle
What is included in a full urinalysis?
- Macroscopic examination (colour etc)
- Microscopic examination
- Chemical examination (dipstick, USG)
- Microbiological examination by culture
What should the findings of a normal macroscopic urinalysis be?
- Colour: light yellow/amber
- Odour: should not be offensive
- Transparency/turbidity: transparent but concentrated and end flow samples more likely to be turbid (sediment)
What is involved in a routine urine chemistry?
- Urine specific gravity
- pH
- Dipstick tests
What are the disadvantages of dipstick tests for animals?
- Do not give exact figures
- Are made for humans so are not 100% accurate for animals
Which results on a dipstick should be ignored?
- SG
- Urobilinogen
- Nitrite
- Leucocytes
- Care with pH
- Care with bilirubin
What is looked for in microscopic examination of urine sediment?
- Crystalluria
- Renal tubular casts
- Epithelial cells
- Blood cells
- Bacteria
- Concentrate debris in urine using centrifuge
- Stain sediment, view under LM, often need high power
What is pH assessment of urine useful for?
- Important in management of urolithiasis
- Meters more precise method of measurement
What are the advantages of taking a urine sample in the early morning or after fasting?
- Most concentrated sample, useful for evaluating concentrating capacity
- Gives highest yield of cells, casts and bacteria
What are the disadvantages of taking a urine sample in the early morning or after fasting?
- Glucosuria may be less obvious than in post-prandial samples
- Cells may be altered due to prolonged exposures to variations in pH and osmolarity
What are the advantages of taking a recently formed urine sample?
- Cells more easily recognisable on microscopy
- Fastidious bacteria which are inhibited by urine may be easier to detect
What are the disadvantages of taking a recently formed urine sample?
- Sample more dilute as has drunk recently so concentrating ability more difficult to assess
- More dilute sample amy cause lysis of cells
What are the methods of urine storage and what is their function?
- Plain sample (no additive)
- Boric acid (preserved, usually micro analysis)
- Formaldehyde (preserve cells for cytology)
How should a urine sample be stored?
- Preferably analyse withiin hour of collection
- Refrigerate and warm to room temp before analysis if longer
What are the indications for urinalysis?
- Signs of renal disease, lower urinary tract disease, many medical problems (esp with multi-systemic signs)
- Part of geriatric or pre-anaesthetic screen
Why might crystalluria be seen in a sample?
- Precipitate out when urine saturated with dissolved minerals
- Do not indicate presence of or predisposition to form urinary calculi
- May get without disease
- Prolonged or cold storage
- Some are normal
What are renal tubular casts?
Proteinaceous plugs of dense, mesh-like mucoprotein +/- cells accumulated in distal portion of the renal tubule
What is the importance of renal tubular casts in urinalysis?
- Low number (<2/HP field) can be normal
Increased number relates to tubular disease - Try to identify associated cells e.g. epithelial, WBC, RBC
What is the importance of epithelial cells in urinalysis?
- Routinely see small number (<2/HP field)
- can be used to identify location of disease if increased number
What epithelial cells may be seen on urinalysis and where do they originate?
- Renal tubular cells
- Transitional cells: renal pelvis, ureter, bladder, proximal 2/3 urethra
- Squamous cells: distal to urethra
Explain the importance of bacterioa in urinalysis
- Absence does not rule out UTI
- May be present for reasons other than UTI e.g. contamination or overgrowth in stored sample
What may cause glucose presence on urinalysis?
- Glucose contamination (e.g. jam jar contamination)
- Glucose present: diabetes mellitus, very stressed cat, renal damage in some renal disease
What may bilirubin on urinalysis indicate?
- Liver disease or haemolysis
What may ketones on urinalysis indicate?
- Ketosis in cattle
- Pregnancy toxaemia in sheep
- Starvation
- Diabetes mellitus
What may urobilinogen on urinalysis indicate?
- Trace is normal
- Positive can mean haemolytic disease or liver disease
What may leucocytes on uriarlysis indicate?
Urinary tract inflammation or infection
Why may struvite crystals be found in urine? Describe their appearace and components
Occasionally seen in normal cold, concentrated, alkaline urine
- 3 to 8 sided prisms, coffin lids
- Magnesium ammonium phosphate
Why might calcium oxalate crystals be found in urine? Describe their appearance
- Acidic or neutral urine
- Small numbers normal in dogs and horses
- Large number indicate ethylene glycol toxicosis
- Dihydrate = small squares with X
- Monohydrate: long rectangular or dumbbel shaped
In what urine are calcium carbonate crystals normal? Describe their appearance
Rabbit and horse
Round or granular
Why might cystine crystals be seen in urine? Describe their appearance
Genetic defect in renal handling of cystine
- Flat colourless hexagons
Why might suphonamide crystals be seen in urine? Describe their appearance
- Animals being treated with sulphonamide
- Needle shaped dark crystals
