Contributors: Vetstream Ltd
Species: Canine | Classification: Techniques
- Introduction or negative or positive contrast into the urinary bladder.
- Allows visualization of radiolucent masses, calculi, foreign bodies and assessment of bladder wall.
- Investigation of dysuria.
- Investigation of hematuria Hematuria.
- Evaluation of caudal abdominal masses that may be associated with the bladder.
- Assessment of bladder integrity following trauma.
- Identification of position of bladder when not visible on plain films.
- Relatively simple procedure in most patients.
- Dependent upon method of restraint.
- If chemical restraint (GA or sedation) required about 5 minutes to gather equipment.
- 30 minutes dependent largely upon skill or radiographer and cooperation of patient.
Criteria for choosing test
- Is the examination appropriate?
- Can you make the diagnosis without it?
- Will your management of the case be affected by the outcome of the examination?
- Risk of air embolus with pneumocystogram if severe hematuria.
- Risk of bladder rupture if excessive contrast inserted.
- X-ray machine.
- Processing facilities.
- Protective clothing (lead apron) for radiographer.
- Positioning aids (sandbags and ties).
- Method of labelling film.
- Recepticle for collecting urine.
- Ability to process films during procedure so that repeat radiographs can be made during course of study if required.
- High output x-ray machine.
- High definition screen.
- Grid for examination of large dog.
- Radiographic film and cassette.
- Contrast agent - air, CO2, N2O, water soluble contrast.
- Urinary catheter.
- Sterile water-soluble lubricant (KY jelly).
- Three way tap.
- Starve animal for 12 hours prior to procedure to reduce fecal content in colon.
- Sedation is advised to facilitate restraint in all radiographic procedures.
- Some animals may require general anesthesia.
- Administration of an enema Enema several hours before procedure to ensure colon empty.
Step 1 - Plain radiographs
- Plain abdominal radiographs Radiography: abdomen should always be taken prior to contrast study to
- Check exposure settings.
- Confirm animal adequately prepared ie colon empty.
- Confirm positioning adequate.
- Check diagnosis not apparent on plain radiograph.
Step 1 - Disinfect prepuce or vagina
- Swab area with diluted surgical scrub.
Step 2 - Catheterize bladder
- Premeasure length of urethra from plain radiograph.
- Using sterile technique, lubricate tip of catheter with sterile lubricant (KY jelly).
- Insert catheter into urethra Urethral catheterization: male to pre-measured length.
- Attach three way tap.
In females a foley catheter Urethral catheterization: female is preferable.
Step 3 - Empty bladder
- Empty bladder of urine using syringe.
- Measure volume of urine removed.
Step 1 - Instill contrast
- Attach syringe filled with contrast to three way tap.
- Inject contrast slowly.
- The volume of contrast injected should usually be the same as the volume of urine removed.
- It may be possible to palpate the bladder through the body wall in which case inject until bladder feels tense.
- Stop injection if resistance to injection is felt or until contrast leaks round the catheter.
- If in doubt as to degree of bladder filling, take radiograph to assess bladder filling.
If using a foley catheter be careful not to overinflate bladder.
Step 2 - Take radiograph
- Lateral and oblique left and right lateral projections should be taken.
- Oblique projections reduce superimposition of spine on bladder.
- Assess degree of bladder filling.
- Bladder needs to be moderately distended to evaluate blader wall thickness.
If bladder under filled erroneous diagnosis of bladder wall thickening may be made.
- If bladder under filled inject more contrast and repeat radiographs.
Step 3 - Empty bladder
- Re-attach syringe to three way tap and remove contrast.
- Remove catheter.
Fatal air embolus
- Reported following pneumocystography.
- Rare and most likely if severe hematuria.
It may be safer to use positive contrast or CO2 or N2O as they are more soluble in serum than air.
- Can occur if overinflate with contrast.
Minimize risk by measuring volume of contrast injected and stop if resistance to injection felt.
- If suspecting bladder rupture, eg post RTA, use positive contrast.
- Sharp pointed catheters may penetrate bladder wall if inserted too far.
- May occur if catheter is inserted too far.
- Will require cystotomy to remove.
Pre-measure length of urethra from control film to avoid this complication.
Reasons for Treatment Failure
- Inability to catheterize bladder.
- Misdiagnosis of bladder wall thickening if insufficient contrast injected.
- May have mucosal abnormalities which may not be apparent on radiography.
- Overinflation of bladder may result in false negative diagnosis.