Antegrade Urethral Catheterization
Urethral catheterization is typically a fairly simple and routinely performed procedure in veterinary patients primarily used to monitor urine output, establish urine drainage in patients that are recumbent or have mechanical/functional urethral obstructions, or to provide urethral patency following urethral or urinary bladder surgery. Occasionally, standard retrograde catheterization can be difficult in very small (female) patients or feline patients with urethral tears following attempts to “de-obstruct” blocked cats or secondary to trauma. Antegrade urethral catheterization performed under direct fluoroscopic visualization can be performed rapidly, easily, and safely in patients in whom attempts at routine retrograde catheterization have failed.
Under general anesthesia (recommended) or heavy sedation, the patient is placed in lateral recumbency and the flank and caudal ventral abdomen are clipped and scrubbed. Cystocentesis is performed and contrast is injected to define the urinary bladder and urethra. Under fluoroscopic guidance, a guidewire is advanced through the cystocentesis catheter and passed antegrade into the bladder and down the urethra until exiting the penis or vulva. A urinary catheter is advanced over-the-wire in a retrograde fashion into the urinary bladder and the guidewire is removed. The urinary catheter is secured in place in a routine fashion (FIGURE 5).
Figure 5. Antegrade urethral catheterization in a cat following iatrogenic urethral tear during attempted retrograde catheterization for urinary obstruction. (A) Retrograde contrast urethrogram through tomcat catheter (black arrows) demonstrating peri-urethral contrast extravasation (*) and non-catheterized actual urethral lumen (white arrows). (B) Percutaneous cystocentesis with 18 gauge catheter (white arrow) and contrast cystogram of urinary bladder (UB). (C) Fluoroscopic-guided antegrade passage of hydrophilic angled guidewire (black arrows) through catheter (white arrow) and down urethra. (D) Retrograde passage of 5 Fr open-ended catheter (white block arrows) over the guidewire (black arrow) and up to 18 gauge catheter (white arrow). (E) Radiograph following removal of guidewire and 18 gauge catheter leaving urinary catheter (white block arrow) in place for urinary drainage while urethral tear heals.