Radiography: cystography

• 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.

Advantages

• Relatively simple procedure in most patients.
• Non-invasive.

• Ultrasonography.
• Double contrast cystography Radiography: double contrast cystography  - shows mucosal detail better.

Preparation

• Dependent upon method of restraint.
• If chemical restraint (GA or sedation) required about 5 minutes to gather equipment.

Procedure

• 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 assessment

• Risk of air embolus with pneumocystogram if severe hematuria.
• Risk of bladder rupture if excessive contrast inserted.

Minimum equipment

• X-ray machine.
• Processing facilities.
• Protective clothing (lead apron) for radiographer.
• Positioning aids (sandbags and ties).
• Method of labeling film.
• Receptacle for collecting urine.

Ideal equipment

• Ability to process films during procedure so that repeat radiographs can be formed during course of study if required.
• High output x-ray machine.
• High definition screen.

Minimum consumables

• Radiographic film and cassette.
• Contrast agent - air, CO2, N2O, water soluble contrast (organic iodine 125 mg/ml).
• Urinary catheter (Tom cat or small Foley).
• 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 to premeasured length.
• Attach three way tap.

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.

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 bladder 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

• Reattach 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.

Bladder rupture

• 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.

Knotting or kinking of catheter

• May occur if catheter is inserted too far.
• Will require cystotomy to remove.
• Premeasure length of urethra from control film to avoid this complication.

• 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.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Johnston G R, Feeney D A & Osbourne C A (1982) Urethrography and cystography in cats - 1. techniques, normal radiographic anatomy and artefacts. Comp Cont Ed 10, 823-836.
• Thayer G W, Carrig C B & Evans A T (1980) Fatal air embolism associated with pneumocystography in a cat. JAVMA 176 (7), 643-645 PubMed.
• Zontine W J & Andrews L K (1978) Fatal air embolization as a complication of pneumocystography in two cats. JAVRS 19 (1), 8-11 VetMedResource.