THE DIAGNOSIS OF BLADDER OUTLET OBSTRUCTION IN MEN BY ULTRASOUND MEASUREMENT OF BLADDER WALL THICKNESS

Purpose: The objective of the study was to investigate specificity and sensitivity of bladder wall thickness in the diagnosis of bladder out let obstruction.Materials and Methods: The study included 174 patients referred to our prostate centers for lower urinary tract symptoms. Fr ee uroflowmetry and pressure-flow studies were performed in duplicate as part of the diagnostic evaluation. After the 2 voiding studies were done the bladder was filled to 150 ml. and wall thickness was measure d via suprapubic ultrasound. Bladder outlet obstruction was diagnosed and graded according to the Abrams-Griffiths and Schafer nomogram as w ell as to the group specific urethral resistance algorithm. Results: A significant correlation (r >0.6, p less than or equal to 0.007) was f ound between bladder wall thickness and all parameters of the pressure -flow study. A bladder wall thickness of 5 mm. appeared to be the best cutoff point to diagnose bladder outlet obstruction, since 63.3% of p atients with bladder wall thickness less than 5 mm. were unobstructed while 87.5% of those with a bladder wall thickness 5 mm. or greater we re obstructed. Bladder wall thickness out performed uroflowmetry in te rms of specificity and sensitivity in the diagnosis of outlet obstruct ion as demonstrated by an area under curve value of 0.860 versus 0.688 in the receiver operator characteristics analysis. Conclusions: Measu rement of bladder wall thickness appears to be a useful predictor of o utlet obstruction with a diagnostic value exceeding free uroflowmetry although it does not represent a substitution to invasive urodynamics. These data support the hypothesis that the relationships between morp hology and function are of clinical importance.