Feline Perineal Urethrostomy Ventral Approach

Clara S.S. Goh, BVSc, MS, Diplomate ACVS, and Howard B. Seim III, DVM, Diplomate ACVS

Experience one of the excellent education sessions provided by experts at the NAVC Institute 2014. A step-by-step surgical intervention of the blocked male cat: tools, surgical insights, postoperative management, complications, and prognosis.

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Over the past decade, advances in the medical management of feline lower urinary tract disease (FLUTD) have decreased the requirement for surgical intervention of the blocked male cat.
Perineal urethrostomy (PU) is still the surgical treatment of choice for patients with:

• Repeated urethral obstruction despite medical management
• Obstruction that cannot be relieved by urethral catheterization
• Catheterization that has resulted in significant urethral trauma and/or stenosis.¹

INITIAL MEDICAL MANAGEMENT

Prior to anesthesia for an elective PU, manage the patient medically with IV fluid therapy and bladder decompression (via retropulsion of urethral crystal/mucus plugs or calculi, catheterization, repeat cystocentesis, or a temporary cystostomy tube) until all renal, metabolic, and electrolyte parameters are within normal limits.

FELINE PERINEAL URETHROSTOMY (DORSAL RECUMBENCY)

Our preferred technique is a slight variation on the traditional PU described by Wilson and Harrison in 1971.² In this variation, the cat is placed in dorsal recumbency instead of the standard perineal approach. This positioning is more ergonomic for the surgeon, and allows access to the ventral abdomen for concurrent cystotomy if indicated.

1. Position the cat in dorsal recumbency (see Surgical Insight: Penile Orientation) with the hindlimbs tied cranially until the pelvis is slightly elevated off the surgery table. Place a folded towel under the pelvis to support the patient (A and B) and place a purse string suture in the anus. Clip and aseptically prepare the perineal region ± ventral abdomen (if a cystotomy is indicated).

2. If the cat is intact, perform a routine castration. The urethra can be catheterized with a Tomcat catheter to aid identification and manipulation. Make a symmetric, elliptical incision around the scrotum and penis (A) at the junction of the perineal and scrotal skin. Perform a circumferential dissection of the subcutaneous connective tissues to isolate the penis (B).

3. With the penis pulled caudally, dissect the ventral connective tissue to isolate the paired ischiocavernosus muscles (A, asterisks), which attach the penis to the pelvis (see Surgical Insight: Ischiocavernosus Muscles). Transect these muscles at their attachment to the ischium (B, dotted line); then sharply and bluntly dissect the ventral penile ligament until the penis can be freely retracted caudally from any ventrolateral pelvic attachments (C).

4. The penis is now reflected cranially, allowing the surgeon to work on its dorsal aspect (A). Identify the thin retractor penis muscle on the dorsal midline directly overlying the urethra (B). Carefully isolate it, and use a combination of blunt and sharp dissection with Metzenbaum or Stevens tenotomy scissors to free and transect its attachment to the penis (C).

5. Use the transected and isolated retractor penis muscle as a guide for continued careful dorsal dissection in the same tissue plane, which exposes the urethra to the level of the paired bulbourethral glands. Dorsal dissection is complete once the paired bulbourethral glands (B) are identified dorsolateral to the transected ischiocavernosus muscles (asterisks). Do not carry out any further dorsal peri-penile dissection once these glands are visualized.

6. Transect the scrotal and preputial skin to expose the tip of the penis (A), and remove the urethral catheter. Use Stevens tenotomy scissors to make a longitudinal incision into the urethral lumen, starting distally and continuing on the dorsal midline to the level of the bulbourethral glands (B, white arrow). See Surgical Insights: Bulbourethral Glands and Urethrotomy Incision.

7. If the urethrostomy opening is thought of as a clock face (with the dorsal aspect pointing toward the anus at 6 o’clock), the most critical sutures are at the 6, 4, and 8 o’clock positions. The 4 o’clock and 8 o’clock interrupted sutures are placed first, leaving the suture ends long as stay sutures to aid in retraction of the tissues.

8. A mattress suture can be placed in the 6 o’clock position (see Surgical Insights: Sutures and Tissue Handling). This tissue bite sequence has 4 steps. The needle:

1. Engages split thickness skin (A)
2. Penetrates the urethral mucosa (into urethral lumen) (B)
3. Passes back through the urethral mucosa (from lumen out) (C)
4. Passes split thickness skin.

9. The remaining interrupted sutures of the PU site are placed in a dorsal to ventral sequence (A through C).

10. Following transection of the penis, the most ventral suture (A) should act as an encircling suture to ligate the penile stump (B); thus, controlling penile hemorrhage. Alternatively, a separate encircling suture can be placed around the penile stump.

11. The penis is amputated (A and B).

12. Complete the PU by closing the remaining skin incision using a simple continuous or interrupted pattern (A and B).

POSTOPERATIVE MANAGEMENT

Postoperative management includes:

• Appropriate pain management
• Monitoring urine output
• Continuation of IV fluid diuresis (at least 24 H post-surgery)
• Ensuring the patient cannot damage the repair (eg, E-collar, litter that will not adhere to the surgery site).

A postoperative indwelling urethral catheter is not indicated in a routine PU.

COMPLICATIONS

Educate owners about potential acute complications, such as hemorrhage, re-obstruction, urine dissection into the subcutaneous tissues, incisional dehiscence, urinary tract infection, urine scald, incontinence, and stricture.^1,4,5

Although the management of such complications is beyond the scope of this article, adhering to the basic surgical principles of delicate tissue handling, careful dissection, tension-free closure, and perfect mucosa-to-skin apposition should minimize occurrence of such complications.
Recurrent bacterial cystitis is the most common late complication, and appropriate ongoing medical management of the underlying FLUTD helps prevent it.^4,5

PROGNOSIS

The overall prognosis following PU is good, with around 90% of clients reporting a satisfactory long-term quality of life.^4,5

FLUTD = feline lower urinary tract disease; PU = perineal urethrostomy

References

1. Williams J. Surgical management of blocked cats. Which approach and when? J Feline Med Surg 2009; 11:14-22.
2. Wilson GP, Harrison JW. Perineal urethrostomy in cats. JAVMA 1971; 159:1789-1793.
3. Sackman JE, Sims MH, Krahwinkel DJ. Urodynamic evaluation of lower urinary tract function in cats after perineal urethrostomy with minimal and extensive dissection. Vet Surg 1991; 20:55-60.
4. Ruda L, Heiene R. Short- and long-term outcome after perineal urethrostomy in 86 cats with feline lower urinary tract disease. J Small Anim Pract 2012; 53:693-698.
5. Bass M, Howard J, Gerber B, Messmer M. Retrospective study of indications for and outcome of perineal urethrostomy in cats. J Small Anim Pract 2005; 46:227-231.

Clara S.S. Goh, BVSc, MS, Diplomate ACVS, Founding Fellow Surgical Oncology, is a faculty surgeon at Colorado State University College of Veterinary Medicine and Biomedical Sciences. She graduated from Sydney University (Australia), and completed her internship, surgery residency, and surgical oncology training at CSU.

Howard B. Seim III, DVM, Diplomate ACVS, is on the surgical team at Colorado State University College of Veterinary Medicine and Biomedical Sciences. He was chief of CSU Small Animal Surgery and founder of VideoVet, a veterinary surgery continuing education video series (videovet.org). He was selected as the NAVC 2009 Small Animal Speaker of the Year. He received his DVM from Washington State University, and completed a 2-year surgical residency at The Animal Medical Center in New York City.