ABSTRACT
<p><b>OBJECTIVE</b>To analyze the value of the diagnostic criteria for bladder outlet obstruction in benign prostatic hyperplasia (BPH).</p><p><b>METHODS</b>A total of 358 patients with BPH were divided into 3 grades according to fibrous urethrocystoscopy information on the severity of obstructions, which were classified as Grade 1 (slight), Grade 2 (moderate), and Grade 3 (severe). By Schäfer's graph they were divided into 7 grades, represented by 0 to VI. We analyzed the volume of prostate, maximum flow rate (Qmax), residual urine volume, International Prostatic Symptom Score (IPSS) and detrusor instability. Statistical analysis ANOVA (analysis of variance) was made, spearman correlation evaluated and the coefficient of determination measured.</p><p><b>RESULTS</b>Of all the patients, 27 were classified as Grade 1, 236 as Grade 2 and 95 as Grade 3. Eighty-four patients had detrusor instability. The volumes of the prostate ranged from 16 ml to 145 ml, averaging (47.04 +/- 15.61) ml. The mean maximum flow rate was (10.02 +/- 2.12) ml/min and the mean residual urine volume was (84.06 +/- 36.50) ml. With the increase of the severity of obstruction, the volume of the prostate increased (F = 4.216, P < 0.05), IPSS rose (F = 8.408, P < 0.001), the maximum flow rate decreased (F = 22.43, P < 0.001), the residual urine volume rose (F = 163.232, P < 0.001), the incidence of detrusor instability increased (F = 23.637, P < 0.001) and Schäfer's grades were elevated (F = 202.897, P < 0.001). The volume of the prostate, the maximum flow rate (Qmax), residual urine volume, IPSS detrusor instability and Schäfer's grades were all correlated significantly with the severity of the obstruction. The correlation index and coefficient of determination were r = 0.29, R2 = 0.08; r = 0.35, R2 = 0.12; r = -0.69, R2 = 0.47; r = 0.60, R2 = 0.36; r = 0.33, R2 = 0.11; r = 0.72, R2 = 0.52; respectively. The correlation between the urethrocystoscopy information and Schäfer's graph on the severity of the obstruction were the best criteria of all.</p><p><b>CONCLUSION</b>The severity of the obstruction at urethrocystoscopy correlates well with that at urodynamic investigation. Such criteria could improve the sensitivity and specificity of the diagnosis of bladder outlet obstruction.</p>