Ventral dissection increases urethral translation length in feline perineal urethrostomy: a cadaveric study

Ventral dissection increases urethral translation length in feline perineal urethrostomy: a cadaveric study

Abstract

Objectives Postoperative stenosis of the urethral orifice is a potential complication of perineal urethrostomy, often caused by inadequate periurethral dissection leading to craniocaudal tension on the stoma. The aim of this study was to evaluate the length of the urethra translated caudally at each step of the dissection of the penile urethra during perineal urethrostomy.

Methods Staged dissection for perineal urethrostomy was performed on fourteen male cat cadavers. Measurements of urethral length were recorded at each stage using digital callipers and standardized traction. Location of the bulbourethral glands relative to the caudal aspect of the ischium was documented. Descriptive statistics were performed.

Results Each stage of dissection led to an increase in urethral translation length, with an overall mean increase of seventeen plus or minus one point nine four millimeters. The most significant increase occurred after blunt dissection of the fibrous attachments between the ventral surface of the urethra and the dorsal surface of the pubis, extending to the pubic brim, accounting for forty-three point one percent of the total translation length. Ventral dissection resulted in a three point nine-fold increase in urethral translation length compared with dorsal dissection. After the final stage of dissection, bulbourethral glands were either level with the caudal edge of the ischium or below the ischium.

Conclusions and relevance Ventral dissection of the fibrous attachments between the urethra and pelvis effected significant caudal translation of the urethra. This step is crucial for minimizing tension on the final stoma and reducing the risk of postoperative stenosis for perineal urethrostomy.

Introduction

Perineal urethrostomy is a surgical procedure commonly performed in male cats affected by recurrent urethral obstruction. Perineal urethrostomy is frequently utilized as a salvage procedure in cases where patients have not responded adequately to medical therapies. These cases may include multiple catheterizations as a result of recurrent feline lower urinary tract disease, penile/urethral trauma, urolithiasis and penile mass. The perineal urethrostomy approach creates a new and permanent opening at the more proximal pelvic urethra, which is nearly twice the diameter of the penile urethra, thereby reducing the risk of obstructions.

Although perineal urethrostomy has been shown to be an effective treatment option, it has a reported short-term complication rate of thirteen to sixty-two point two percent, and a long-term complication rate of fourteen point three to thirty-one point eight percent. Postoperative stenosis of the urethral orifice is a commonly reported complication, with a prevalence of two point five to twenty percent, often due to poor surgical technique. In two thousand six, Phillips and Holt reported that eight out of eleven cats required revision because of inadequate dissection of the penile urethra from its attachments at the ischium to the level of the bulbourethral glands. In that study, excessive tension on the mucocutaneous junction apposition and suturing of narrower penile urethra subsequently led to contraction and the development of stenosis.

The long-standing recommendation for dissection to the level of the bulbourethral glands during perineal urethrostomy is based on the quantitative evidence demonstrating that the urethra is wider at this location. In addition, it has been suggested that urethral mobilization after perineal urethrostomy occurs through caudal translation rather than elongation by stretching; however, there is limited information on the extent of urethral translation achieved during dissection. To the authors' knowledge, there is no comprehensive description of the surgical technique for maximizing caudal translation of the pelvic urethra at each stage of the dissection or identifying the key steps that maximize this translation. This information would be valuable to veterinary surgeons for precise technical execution of perineal urethrostomy. Therefore, the aim of the present study was to measure and document the length of the urethra translated caudally at each step of the dissection of the urethra during perineal urethrostomy, from the initial dissection of penile attachments to the final mobilization. It is the authors' impression that maximizing urethral translation may lead to reduced craniocaudal tension on the stoma, aiding in accurate, tension-free mucocutaneous apposition, uncomplicated wound healing, and the formation of a patent and appropriately sized stoma. We hypothesized that the greatest increase in translation would occur after the blunt dissection of the ventral fibrous attachments between the urethra and the dorsal surface of the pubis, to the level of the pubic brim.