What to do when urethral catheterization is not possible (Proceedings)
Urolith in the urethra, most commonly composed of calcium oxalate.
1. Patient Presentation
a. Male cat presented for "constipation" for a day
b. Abdominal palpation reveals a very large, painful, and hard urinary bladder.
c. You tell the owner: "No problem."
d. Famous last words!
2. Your Attempts
a. Anesthesia is given.
b. A catheter is chosen and lubricated.
c. In spite of repeated efforts, pleas for Divine intervention, and promises to God, you cannot get the catheter to pass into the bladder.
3. What to do Next
a. Radiograph the abdomen caudal enough to include the urethra.
i. You should do this with all obstructed cats.
b. Empty the bladder with a cystocentesis.
c. Attempt catheterization again
i. Immediately.
ii. If that is not successful, in 6-12 hours.
4. Possibilities
a. Urolith in the urethra, most commonly composed of calcium oxalate. *****
b. Soft tissue stricture ***
i. In urethra.
ii. In penis.
iii. Usually due to prior difficult or abusive catheterization.
c. Heavy struvite crystalline debris in the bladder and urethra. *
d. Urethral tumor. *
5. Two Important Diagnostics
a. Plain Radiographs of Abdomen
i. Take a lateral view caudally enough to include the urethra.
ii. A struvite urolith is less radiodense than a calcium oxalate urolith and could be missed with a film radiograph. Consider digital (DR) radiography for your practice.
b. Urethrogram
i. Technique
1. Anesthesia.
2. Pass a catheter about 0.5-1.0 cm into the urethra.
3. Occlude the urethra around the catheter.
4. Inject 1 ml of an IV-approved contrast material (MD-76R or Omnipaque); do not use barium.
5. Take a lateral radiograph immediately with the catheter still in the urethra.
6. A normal urethra has a slight bulge at the level of the bulbourethral glands. This is seen about the level of the caudal end of the pelvis.
7. Note: If the stricture is in the penis so a catheter cannot be passed, you will not be able to perform a urethrogram; go to surgery immediately.
6. Surgical Options
a. Perineal Urethrostomy
i. Goal: to remove the tapering small-diameter section of the urethra.
ii. This should prevent future obstructions.
iii. It will not prevent future episodes of cystitis.
iv. These cats are more prone to ascending bacterial cystitis because the urethra is smaller and of larger diameter, very similar to the female cat.
v. Properly performed, it will reach the large diameter portion of the urethra.
1. Almost all soft tissue or urolith obstructions are more distal.
vi. Passage of a urethral catheter is mandatory.
1. The catheter allows you to identify the urethra and its lumen.
2. If not, you may cut the urethra while trying to dissect it free of its dorsal, ventral, and lateral attachments.
3. You must identify the lumen to split the urethra longitudinally.
4. Catheter passage; soft tissue obstruction
a. If the catheter will pass at least 1.0 cm, it is likely that you can relieve the obstruction as you split the urethra to the end of the catheter.
5. Catheter passage; obstruction due to uroliths
a. These bury into the urethral mucosa resulting in mucosal swelling and further preventing their movement retrograde or antegrade.
b. It is unlikely that you will move them with a catheter if they have been embedded for 12+ hours. Prior to that, it may be possible to push them back into the bladder.
c. However, if the catheter will pass at least 1.0 cm, it is likely that you can remove the urolith as you split the urethra to the end of the catheter.
6. Important: If you cannot pass a catheter at least 1 cm, do not attempt a perineal urethrostomy.
b. Cystotomy and Antegrade Catheter Passage
i. The one way valve effect often happens when traumatic catheterization creates a scar tissue stricture that forms so that a catheter will not pass retrograde but will pass antegrade.
ii. Traumatic catheterization results from overzealous (sometimes desperate) efforts with a stiff catheter that traumatizes the urethra.
1. If you cannot pass the catheter after 2-3 attempts at back flushing, do not proceed with repeated thrusts of a catheter.
2. When the urethral lining looks like hamburger meat, a PU is MUCH more difficult to perform and predisposes the cat to future stricture formation at the stoma.
iii. Procedure
1. Do a cystotomy with the opening on the ventral surface (in case you need to perform a cystostomy).
2. Pass a 5 Fr. catheter through the urethra.
a. Use 22 ga. stainless steel wire as a stylet to give it sufficient rigidity to pass.
b. Lubricate the tip of the catheter with sterile lube.
c. If successful, there is a one-way valve effect.
i. This happens when traumatic catheterization creates a scar tissue structure that forms so that a catheter will not pass retrograde but will pass antegrade.
3. Secure the catheter to the perineal area of the cat so it does not slide out of the urethra prematurely.
4. Reposition the cat, prep the area, and return to the bladder.
5. Cut off the excess catheter, including the flared portion, so the catheter will fit into the bladder.
6. Close the bladder and abdominal wall with the catheter still in the urethra.
7. Perform a perineal urethrostomy as usual.
8. After splitting the distal urethra, the red rubber catheter can be replaced with a stiffer tom cat polypropylene catheter.
c. Bladder Marsupialization (Cystostomy)
i. If the catheter will not pass in an antegrade direction, remove it through the opening on the ventral surface of the bladder.
ii. Attach the bladder wall to the body wall with 3-0 Vicryl or equivalent and skin leaving a 1 cm opening for urine to flow directly to the outside.
iii. Close the remainder of the body wall.
iv. Protect the skin from urine scalding with No Sting Barrier Spray (3M) or Desitin Ointment.
v. Leave the cystotomy open for 2-5 days to allow swelling in the urethral mucosa to subside so the catheter will pass retrograde.
vi. The urolith is pushed into the bladder where it is removed.
vii. Close the bladder wall.
viii. Close the abdominal wall.
ix. A PU is not needed.
x. Note: This is the procedure employ if the cat is a valuable breeding cat.
1. His reproductive capability remains intact.
xi. This should be considered a temporary solution to allow the bladder to empty.
1. Leaving the cystostomy open long-term results in irritative dermatitis (urine scalding) and cystitis due to antibiotic resistant bacteria.
7. Catheter types
a. Olive Tipped Metal Catheter, Jorgensen Laboratories
b. Red Rubber Catheter, 3.5 Fr; Kendall Sovereign
i. Note: Passing too much catheter into the bladder can result in the tip of the catheter going down (antegrade) the urethra and causing an obstruction that can only be relieved surgically.
c. Polypropylene Tom Cat Catheter, 3.5 Fr; Kendall Sovereign
d. Tom Cat Catheter with Wire Guide; Global Veterinary Products
e. KatKath Adjustable and Fixed Length Catheters; DVM Solutions
8. Tips on Catheter Passage
a. Positioning (For a right handed person)
i. Place the cat in right lateral recumbency with the LR leg pulled laterally and cranially.
b. To Extrude the Penis
i. Place your index finger and your thumb dorsal and ventral to the prepuce.
ii. Apply firm, steady pressure cranially.
c. To Break the Obstruction
i. Insert the Olive Tipped Catheter no more than 1 cm into the urethra and inject saline with firm, steady pressure on the syringe plunger.
d. Insert the Indwelling Catheter
i. Pull caudally on the prepuce to straighten the urethra.
ii. Insert the catheter of choice.
e. Advance the Catheter
i. Continue to flush while advancing the catheter.
ii. Remove the syringe and advance the catheter until urine flows.
f. Bladder Flush
i. Flush 30-40 ml of saline into the bladder. Remove it. Repeat 1-2 times.
