Diagnostic accuracy of noninvasive tests to evaluate bladder outlet obstruction in men: detrusor wall thickness, uroflowmetry, postvoid residual urine, and prostate volume

OBJECTIVES: The aim of this prospective study was to compare the diagnostic accuracy of detrusor wall thickness (DWT), free uroflowmetry, postvoid residual urine, and prostate volume (index tests) with pressure-flow studies (reference standard) to detect bladder outlet obstruction (BOO) in men. METHODS: During a 2-yr period, men older than 40 yr with lower urinary tract symptoms and/or prostatic enlargement had the following tests: ultrasound measurements of DWT, free uroflowmetry (Q(max), Q(ave)), postvoid residual urine, and prostate volume. Pressure-flow studies were used to divide obstructed from nonobstructed bladders. RESULTS: One hundred sixty men between 40-89 yr of age (median: 62 yr) were included in the study; 75 patients (46.9%) had BOO according to pressure-flow studies. The results of all investigated index tests differed significantly between obstructed and nonobstructed men. DWT was the most accurate test to determine BOO: the positive predictive value was 94%, specificity 95%, and the area under the curve of ROC analysis 0.93. There was an agreement of 89% between the results of DWT measurement and pressure-flow studies. CONCLUSIONS: Measurements of DWT can detect BOO better than free uroflowmetry, postvoid residual urine, or prostate volume. In clinical routine, DWT measurements can be used to judge BOO noninvasively