New study paves way for prediction of re-obstruction following feline perineal urethrostomy

19 August 2020

A new study, published in the latest issue of the Journal of Small Animal Practice (JSAP), evaluated urethral orifice cross-section dimensions and correlation with stricture formation following perineal urethrostomy in male cats. The work shows that it may be possible to predict the likelihood of re-obstruction and stricture formation occurring following surgery.

Perineal urethrostomy is a procedure used to relieve urethral obstruction in male cats in which medical management had failed. In the procedure, a permanent new stoma is created in the pelvic urethra proximal to the obstruction.

In the study titled “Evaluation of urethral orifice cross-section dimensions following perineal urethrostomy in male cats”, 24 male cats with lower urinary tract disease underwent the procedure. The urethral orifice cross-section was estimated by the largest urinary catheter that could be easily inserted through the stoma at three time points: preoperatively, intra-operatively and 12 days postoperatively. Cases of obstruction recurrence and stricture were documented within the six month follow up period.

Uri Segal, corresponding author for the paper, said: “The intraoperative stoma ranged from 1 to 10 (median 10) Fr and the 12-day postoperative stoma ranged from 4 to 10 (median 8) Fr. There was significant reduction of stoma size 12 days postoperatively, compared to the measurements taken intraoperatively. Postsurgical stricture formation and re-obstruction was documented in five of 24 (21%) of cats. Obstruction recurrence is probable if the intra-operative stoma size is 8 Fr or less. Furthermore, if the stoma size is 6 Fr or less, re-obstruction is almost certain (all of these cases in the study were re-obstructions). Conversely, an intra-operative stoma of more than 8Fr had a low risk of recurrence.”

Nicola Di Girolamo, editor of JSAP concluded: “These findings may function as a guiding rule for surgeons performing perineal urethrostomy, by providing an intraoperative measure of how likely re-obstruction and stricture formation is to occur. It should be remembered, however, that the functional urethral stoma cross-section may vary during the urination cycle and the measurements in this study are likely to only represent a fraction of the functional urethral cross-section size.”

The full article can be found in the August issue of the Journal of Small Animal Practice which is free for BSAVA members. It can also be read online here.

For information on how to become a BSAVA member visit the website here.

1U. Segal, J. Shani, O. Zemer, R. Joseph (2020) Evaluation of urethral cross-section dimensions following perineal urethrostomy in male cats.  Journal of Small Animal Practice, 61 (8). Available at: