To establish a grading system for bladder trabeculation.

A total of 228 patients who underwent videourodynamic studies were retrospectively reviewed. All fluoroscopic images included were gathered and were classified into 4 grades of trabeculation according to maximum depth and portion of bladder surface occupied: 0 (none), 1 (mild, depth <5 mm and area <1/2 of bladder), 2 (moderate, depth 5-10 mm and area ≥1/2 of bladder), and 3 (severe, depth >10 mm and area ≥1/2 of bladder). Presence of vesicoureteral refluxes, urethral leaks, and diverticula were evaluated. Grades were determined by 9 participants, and test-retest reliability was assessed over the span of 2 weeks. To evaluate interobserver and test-retest reliabilities, the intraclass correlation coefficient, Crohn’s kappa, and Spearman’s correlation coefficient were analyzed.

We found the mean trabeculation depths to be 6.5 ± 6.1 mm and with increasing trabeculation grade, refluxes, and urethral leaks increased. The number of diverticula, however, was unrelated to the grade. The interobserver reliability was almost perfect, with the intraclass correlation coefficients of 0.985 in fluoroscopy. Test-retest reliability was strong between repeated grading, and all values of Crohn’s kappa showed almost perfect agreement (from 0.870 to 0.955). Urodynamic results of free uroflowmetry and voiding cystometry showed clinical significance of this trabeculation classification grade.

Interobserver and test-retest reliabilities proved the reliability and validity of the grading system for bladder trabeculation using trabeculation depths and area covering the bladder surface.