Evaluation of urethral orifice cross-section dimensions following perineal urethrostomy in male cats.

Abstract

OBJECTIVES: The aims of this study were: (1) To evaluate the urethral orifice cross-section size immediately and 12&#x2009;days post-operatively following a perineal urethrostomy procedure. (2) To assess the correlation between the cross-section size and stricture formation during a 6-month period following the perineal urethrostomy. ANIMALS: Twenty-four male cats with feline lower urinary tract disease that failed to respond to medical treatment and underwent perineal urethrostomy. MATERIALS AND METHODS: The urethral orifice cross-section size was estimated by the largest size of the urinary catheter that was possible to insert facilely through the urethrostomy site. The urethral orifice cross-section size was measured in three different times: Pre-operative (LUCpr), immediately post-operative (LUCi) and 12&#x2009;days post-operative (LUCp). Urinary obstruction recurrence and urethrostomy site stricture formation were documented for 6&#xa0;months after the surgical procedure. The probabilities for obstruction recurrence in cases of LUCi &#x2264;&#x2009;8Fr and LUCi&#xa0;>&#x2009;8Fr were calculated. RESULTS: Urinary obstruction and urethrostomy site stricture occurred in 5 of 24 (~20%) of the operated cats at an average of 92&#x2009;&#xb1;&#x2009;25&#x2009;days post-perineal urethrostomy. LUCi ranged from 6 to 10 (median 10) Fr and the LUCp ranged from 4 to 10 (median 8) Fr. There was a significant decrease of 0.15&#x2009;&#xb1;&#x2009;0.09&#x2009;mmof the urethral orifice cross-section area 12&#x2009;days post-operative compared to the measurements taken immediately post-operative. The probabilities for post-operative urinary obstruction of the LUCi &#x2264;&#x2009;8Fr cases (intra-operative urethral orifice cross-section area equal or larger than 5.5&#x2009;mm) and in the LUCi&#xa0;>&#x2009;8Fr cases were 44 and 6%, respectively. Recurrence of obstruction was documented in all cases (three cats) in which LUCi was 6Fr. CONCLUSION AND CLINICAL SIGNIFICANCE: The largest size of the urinary catheter that is possible to insert during surgery is a simple method to evaluate urethrostomy cross-section size. Contraction of the urethral orifice diameter is expected during the wound healing phase. Post-operative urinary obstruction is more likely in cases where LUCi <&#x2009;8Fr.