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What is a IVP?
contrast radiology to evaluate the kidneys and ureters
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What are we evaluating with the ureters when doing a contrast study?
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What are we evaluating with the kidneys when doing a contrast study?
- size
- shape
- position
- function
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What is involved in a urinary tract contrast study?
- IVP
- cystography
- urethrography
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What does IVP stand for?
intravenous pyelography
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What is the size of a dog kidney? Cat?
- dog: 2.5 - 3.5 times the size (length of the 2nd lumbar vertebra
- cat: 2.5 - 3 times the size of the 2nd lumbar vertebra
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What is the shape of a dog, cat, horse, and cow kidney?
- dog and cat: typical "kidney bean" shape with smooth borders
- horse: right kidney "valentine heart" shaped
- cow: lobulated
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Can an IVP test for renal function?
no
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What are the factors that affect the kidney's ability to concentrate urine?
- renal failure
- dose of contrast agent
- rate of administration
- route of administration
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What is renal failure?
less concentration
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How do we administer the contrast agent to test for kidney function? Why can't we administer it any other way?
- IV
- it will be irritating and it will not pick up the agent fast enough to opacify the kidneys
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What type of lesions can be detected with IVP?
- renal neoplasia
- cysts
- trauma
- hydroureter
- hydronephrosis
- agenesis
- hypoplasia
- obstructions
- ectopic ureter
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When do we do an IVP?
- abnormal urine (blood, crystals, pyuria, tumor cell)
- abnormal size, shape of kidneys on palpation
- renal failure
- urinary incontinence
- trauma to urinary system
- suspected kidney stone
- masses involving the kidney
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Are kidney stones common in dogs and cats?
no
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What are some precautions for IVP? And how do we prevent them?
- dehydration: rehydrate, keep on fluids
- renal failure: increase dose, maintain hydration
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What contrast agents do we use for IVP?
iodinated (diatrizoate, iothalamate compounds)
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How much iodine do we administer for IVP? What is the maximum we can give? How do we administer it?
- 300 - 400 mg iodine/ml
- maximum 90 ml
- administer rapidly IV catheter over 1 - 3 minutes
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For renal failure patients, if BUN > 50 mg/dl or creatinine is > 4 mg/dl how much iodine do we administer?
give 1700 mg iodine/kg
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How do we prep a patient for IVP?
- fast for 12 - 18 hours
- enemas
- cathartics
- limit fluid intake 12 hours before IVP
- empty bladder before study
- place IV catheter
- survey radiographs (VD and lateral)
- inject contrast agent
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Do we usually use anethesia for IVP?
no
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How do we take the images for an IVP?
- 10 seconds
- 1, 3, 5, 15, 20, 40 minutes
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What can we apply around the wait directly cranial to the hip for an IVP?
compression bandage
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What is the purpose of a compression bandage?
- compress distal ureters
- cause filling of kidney - renal pelvis and collecting tubules
- prevent filling of bladder
- with bandage on, ureters are 2 - 3 times actual size
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What are the phases of IVP?
- arteriogram
- nephrogram
- pyelograpm
- cystogram
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What is the arteriogram?
- immediate
- demonstrates renal blood flow
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What is nephrogram?
- contrast agent is evenly perfused throughout the kidney
- used to evaluate renal parenchyma
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What is pyelogram?
evaluates renal collecting system, including renal pelvis and ureters
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What is cystogram
- drainage into bladder
- does not distend bladder
- can examine junction of ureters and bladder
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Is a cystogram suitable for evaluating the bladder?
no
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What is ectopic ureter evaluation?
see where ureters are connecting bladder, neck, urethera
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How do we do an ectopic ureter evaluation?
- IVP
- drain bladder of urine, inflate with gas
- see entire ureter length
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What is a cystography?
contrast study of bladder by retrograde injection of contrast material
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When was cystography most commonly used?
before we had ultrasound
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What does a cystography evaluate?
- size, shape, location of bladder
- thickness of bladder wall
- distensibility
- ureter-bladder junction
- contents of bladder (stones, masses)
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When do we do a cystography?
- abnormal urine (blood, crystals, segs)
- abnormal urination (dysuria, obstruction, incontinence, straining, increased frequency)
- abdominal masses in area of bladder
- suspected urinary calculi not visible on survey view
- determining location of bladder
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When should we NOT do a cystography?
- severe bladder disease
- dehydration
- cystocentesis - not within 24 hours - may force fluid through hole
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What kind of contrast agent do we use for a cystography?
water soluble iodine compounds
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How do we prep the patient for a cystography?
same as for an upper GI contrast study
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Do we need to use anethesia for cystography?
yes
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What are the steps of cystography?
- pateint prep
- anesthesia
- survey films (VD, lateral, oblique)
- urinary catheterization
- empty bladder
- if blood clots are present, flush with steril saline to remove
- infuse lidocaine into bladder
- infuse contrast agent
- monitor infusion
- radiograph
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How do we do a urinary catherter for cystography?
- aspetic technique - mild scrub, sterile lube, 3-way valve
- remove air from catheter
- fill with contrast agent before insertion - prevent air bubbles
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Why do we infuse the bladder with lidocaine for cystography?
to reduce spasticity which prevents complete distension of the bladder
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What is the goal when administering a contrast agent for cystography?
to fully distend the bladder
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How do we monitor infusion during cystography?
- palpate bladder
- amount of back pressure on syringe
- never force into non-distensible bladder
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What kind of radiographs do we need of cystography?
- VD
- lateral
- right and left obliques
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What do we need to avoid when we are taking radiographs for cystography?
superimposition of hip bones
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Why do we do a double contrast cystography?
shows mucosal detail and masses in lumen
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What do we usually do first in cystography, positive contrast or double contrast?
positive contrast
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How do we do a double contrast cystogram?
- infuse 10 - 30 ml of undiluted positive contrast agent to coat mucosa well
- massage bladder and rotate patient to distribute
- remove undiluted agent
- infuse gas into bladder
- monitor infusion - palpation, back pressure
- radiograph
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What is a negative contrast cystogram?
simple infusion of gas into the bladder
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Does a negative contrast cystogram give us more information than a positive contrast cystogram?
no, gives us less information
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How much do we need to reduce the kVp when doing a negative contrast cystogram?
by 4 - 6
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Can we do a negative or double contrast study if the bladder is ruptured or there is active bleeding suspected? What could happen if we did?
- no
- air embolism is possible
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What can we use instead of room air to do a cystography? Why?
- CO2 or N2O
- 20 times more soluble in blood than air, bubbles dissolve rapidly
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When should we do cultures and sensitivity tests for the bladder?
before doing a cystograph
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What does urethrography evaluate?
distal portion of urinary tract by retrograde infusion of contrast material
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Is a urethrograph usually done in males or females?
males
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What does a urethrograph look for?
- trauma
- rupture
- stricture
- obstruction
- tumor
- invasion
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When would we do a urethrograph?
- abnormal urine
- abnormal urination
- prostate problems in male dogs
- suspected rupture of the urethra
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Waht kind of contrast agent do we use for a urethrograph?
positive - iodine
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How do we mix iodine for a urethrograph?
- dilute to 200 mg iodine/ml with sterile saline
- can mix iodine with K-Y jelly half and half
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Why do we mix iodine with KY jelly for a urethrograph?
- gives good mucosal detail
- good identification of small calculi
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How do we prep patient for a urethrograph?
- same as for an upper GI
- fasting, cathartic, enema
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Can we anesthestize the patient for an urethrograph? Why would you use anesthesia?
- yes it's usually needed
- uncomfortable to pass catheter, fill bladder
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When do we take the radiograph for a urethrograph?
take x-ray as finishing the injection to fully distend urethra
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How do we catheterize for a urethrograph?
- same as for cystogram
- use largest size catheter as possible
- balloon tip is better
- remove air bubbles before insertion
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What might we find when we pass a catheter for a urethrograph?
may find stones in the urethra
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Where does the tip of the catheter go for an urethrograph?
place tip of catheter just inside the urethral orifice
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Which radiograph views do we take for a urethrograph?
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How do we position the animal for an urethrograph?
- position rear legs out of the way
- pull cranial to look at distal urethra
- pull caudal to look at prostatic urethra
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Describe the technique for a voiding urethrogram.
- done after positive contrast cystogram
- bladder full of contrast material is expressed with a paddle
- radiograph is made when urine is seen at tip of urethra
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When should we not do a voiding urethrogram?
if the bladder is badly diseased and may rupture
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Describe the technique for a prostatic urethrogram.
- patient prep (the same as other urinary tract studies) except leave bladder half full or urine or saline
- insert catheter so that the tip in in bladder lumen
- aspirate while slowly pulling catheter out
- when urine flow stops, the tip of the catheter is just within the urethra
- pull catheter back another 1 - 3 cm
- inject contrast agent as for retrograde urethrogram
- take radiograph during injection
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Which radiograph views do we do for a prostatic urethrogram?
lateral and obliques
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What does a prostatic urethrogram look for?
prostatic fistula communicating with the urethra
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