Comparison of urethral length and orifice diameter in cats undergoing transpelvic or subpubic urethrostomy for perineal urethrostomy revision (cadaveric study).

Abstract

Stenosis is a postoperative complication reported in 12-17% of male cats that undergo perineal urethrostomy (PU). This study compared two different revision techniques for failed perineal urethrostomies. The first objective was to evaluate the feasibility of performing a transpelvic urethrostomy (TPU) after a previous, correctly performed PU in male cats. The second objective was to determine the residual urethral length, orifice diameter, and the position of the orifice relative to the pubic brim and anus after PU, TPU and subpubic urethrostomy (SPU). Twenty male cat cadavers were randomly divided into two groups: TPU and SPU. In group TPU, PU was followed by TPU; in group SPU, PU was followed by SPU. After each procedure, the urethral orifice cross-section size was estimated by inserting the largest possible urinary catheter without resistance. Residual urethral length was measured both on contrast radiographs and after anatomical dissection. In all cats, TPU could be performed following a technically correct PU. The TPU resulted in a 1.5-times longer residual urethral length than SPU, based on contrast radiographs (P = 0.001) and confirmed by anatomical dissection (P <0.001). Relative to the initial urethral length, PU, TPU and SPU resulted in a reduction of 24%, 36% and 56%, respectively. The urethral orifice diameter after TPU did not differ from SPU (P = 1.000), and it was not statistically significantly different between TPU and PU (P = 0.317) or between SPU and PU (P = 0.655). The urethral orifice was located further away from the pubis (P <0.001) and closer to the anus (P <0.001) after TPU than after SPU. Both TPU and SPU are possible revision surgeries following PU. As TPU preserves a significantly longer urethral length and requires less tissue dissection, the risk of urinary tract infections, urinary dermatitis and urinary incontinence might be less following TPU than SPU.