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Published on: September 7, 2022
Anin vitro, proof of concept study utilizing a latex model to simulate assessment of urethral pressure profile to
Diboro L Kanabolo1, Noah Roselli2, Emily Ji1
1Department of Urology, Northwestern Memorial Hospital, Chicago, IL, USA.
Background:
Retrograde urethrogram (RUG) remains the gold standard for diagnosing urethral stricture disease, however no widely available diagnostic modality currently quantifies stricture characteristics using cross-sectional area or tissue compliance. We hypothesized that pressure-derived metrics could improve diagnostic accuracy and guide treatment. We aimed to develop an in vitro latex urethra model to simulate "healthy" and "strictured" states and directly measure luminal pressure as an initial step toward compliance assessment.
Methods:
Ten 20-cm latex tubes were studied; five contained 1.5-cm simulated strictures. All tubes were clamped at both ends to prevent leakage. Strictures were created by clamping across an 8Fr bougie at the midpoint, while healthy models were left unclamped at the 8Fr bougie location. Tubes were pressurized for 10 s to simulate RUG conditions. Pressure was measured using a 7Fr air-charged dual-sensor urodynamic catheter positioned such that the midpoint stricture was located 2 cm distal to the first pressure sensor. Saline was infused at 20 mL/min through the catheter port positioned proximal to the stricture, and maximum pressure (Pmax, cmH2O) was selectively recorded only from the first proximal sensor to reflect upstream resistance generated by the narrowing. Time to maximum pressure (Tmax, seconds) was also measured. Compliance was calculated (ΔV/ΔP). Comparisons were performed using an unpaired Student's t-test.
Results:
Ten pressure-time curves were generated. Mean (Standard Deviation) Pmax was significantly higher in strictured models compared to healthy controls (160.8 [9.4] vs. 29.8 [16.4] cmH2O, p < 0.001). Tmax was similar between groups (9.2 [1.1] vs. 9.8 [0.4] s, p = 0.289). Compliance was lower in strictured (0.019 [0.003] cm³/cmH2O) vs. healthy tubes (0.150 [0.107] cm³/cmH2O, p = 0.025).
Conclusions:
This proof-of-concept model demonstrates that pressure profiling can distinguish healthy from strictured urethras and supports compliance as a novel diagnostic metric.
