Clinical Sciences, Université de Montréal, St. Hyacinthe, QC, Canada
Allows antegrade removal of bladder stones through the urethra. Recommended for small stones in female cats and dogs but should not be attempted in male cats.2 Under general anesthesia, a urinary catheter is used to fill the bladder with saline (avoid overfilling, estimated bladder capacity 10–15 ml/kg). The urinary catheter is removed, in females the patient is positioned vertically, males are placed in lateral recumbency. The urinary bladder is palpated, shaken gently, pulled cranially to straighten the urethra. Gentle but steady pressure is applied to the urinary bladder to induce micturition and allow for expulsion of stones. If a female patient cannot be catheterized, filling of the vulva with saline will result in filling of the bladder and the voiding urohydropulsion can still be performed.
Percutaneous Antegrade Urethral Catheterization
Percutaneous antegrade urethral catheterization is indicated when a urethral obstruction cannot be relieved by standard retrograde catheterization, when animals are difficult or too small to catheterize, have a urethral tear, or a distal urethral obstruction. It is most commonly performed in male cats with iatrogenic urethral tears secondary to trauma from serial attempts to catheterize. Because the tear is made in a longitudinal retrograde direction, the antegrade passage is effective. The procedure is done under general anesthesia (fluoroscopic guidance can help but is not obligatory). An intravenous catheter is percutaneously inserted into the apex of the full urinary bladder. Passage of a guidewire (angled hydrophilic 0.18 inch in cats) in an antegrade manner through the catheter, the bladder then down the urethra until it exits through the penis or vulva. The catheter is withdrawn from the bladder apex. An open-ended urinary catheter is advanced in a retrograde manner over the guidewire until it reaches the bladder. The guidewire is removed.
In cases of urethral tears, the urinary catheter should be left in place for 3–5 days to allow complete healing.
This procedure flushes stones from the urethra into the urinary bladder to allow for dissolution or removal. The pelvic/prostatic urethra is compressed by digital rectal palpation. A urinary catheter is inserted into the distal urethra and the urethra is flushed with saline. This results in distension of the urethra. While continuing to flush, digital pressure is released from the urethra allowing the stones to be retropulsed into the bladder. This technique works well with embedded stones, as distension of the urethral mucosa facilitates movement of the stones in a retrograde manner.
Bladder Mass Biopsies
Samples for cytology and histopathology can be obtained for bladder and urethral masses by using this technique. Under ultrasound guidance, the patient is catheterized and the catheter advanced to the mass. Aspiration through a syringe attached to the urinary catheter allows aspiration of the mass, often obtaining pieces of tissue. For a urethral mass found on rectal palpation, but not visible on ultrasound, the same technique can be performed, except that the catheter is advanced to the level of the mass, guided by rectal palpation of the urethra. When the catheter is at the level of the mass, aspirations are performed. This technique works well to remove small stones or clots from the bladder that can be aspirated through the holes of the catheter.
1. Weisse C, Berent A, eds. Veterinary Image-Guided Interventions. Wiley-Blackwell; 2015.
2. Dunn M, Berent A. Urologic interventional therapies. In: Ettinger SJ, Feldman EC, Côté E, eds. Textbook of Veterinary Internal Medicine. Chapter 124. 8th ed. Elsevier; 2016:493–511.
3. Butty E, Vachon C, Dunn M. Interventional therapies of the urinary tract. Vet Clin North Am Small Anim Pract. 2019;49:287–309.