Simultaneous Bladder Drainage via Suprapubic and Urethral Catheters: Which Drains More Completely and Why?

Background: Reconstructive urologists often place both a urethral and suprapubic catheter intraoperatively to prevent extravasation of undrained urine across anastomosis sutures. As no consensus exists on which catheter drains the bladder more completely, many surgeons leave one catheter to gravity drainage and cap the other postoperatively. We sought to identify differences in catheter urine outflow during dual bladder drainage with suprapubic and urethral catheters in postoperative urology patients.

Methods: Urine output (UOP) from transgender men who underwent Stage II Phalloplasty with urethral lengthening was retrospectively reviewed. Both 16 French urethral and suprapubic catheters were placed to gravity drainage postoperatively. Urine output from each catheter was recorded separately, twice daily. Mixed model regression modeling tested for differences in urine output by time of day (day/night) and activity status (Bedrest: Postop Day 0-2, Ambulatory: Postop Day 3+).

Results: The aggregate number of 12-hour shift urine output observations was 250 (125 for urethral and 125 for suprapubic catheters) across 14 inpatients. Suprapubic catheters had a mean 410 ml higher output than urethral catheters per 12-hour shift (p=0.002; 95% CI: 185, 636 ml). During daytime, Suprapubic catheters demonstrated higher UOP than urethral catheters per 12-hour shift (Estimated Difference: 464 ml; p=0.002; 95% CI: 211, 718 ml). During nighttime, a similar phenomenon was observed (Estimated Difference: 356 ml; p=0.009; 95% CI: 104, 606 ml). When comparing mean UOP from each catheter during the Bedrest Phase, suprapubic catheters averaged an estimated 295 ml higher UOP compared to urethral catheters per 12-hour shift with a trend toward statistical significance (p=0.052; 95% CI -3, 594 ml). During the Ambulatory Phase, mean suprapubic catheter UOP was an estimated 472 ml higher than urethral catheters per 12-hour shift (p=0.009; 95% CI 142, 802 ml).

Conclusions: Simultaneous bladder drainage with urethral and suprapubic catheters shows greater drainage from the suprapubic catheter (35% vs 65%). When using two catheters, both can be placed to gravity to maximize bladder drainage as the suprapubic catheter can drain residual urine not adequately drained by the urethral catheter.