Urodynamic obstruction in women with stress urinary incontinence--do nonintubated uroflowmetry and symptoms aid diagnosis?

Purpose: We estimated the prevalence of urodynamic obstruction in women with stress urinary incontinence and determined which clinical indicator (nonintubated uroflowmetry or urinary symptoms) better predicts urodynamic obstruction.
Materials and Methods: From December 2004 to June 2005, 101 women with urodynamic stress urinary incontinence were enrolled. Adjunctive lower urinary tract symptoms were also observed. Of 101 women with stress urinary incontinence 27 had abnormal and 74 had normal nonintubated uroflowmetry. Normal nonintubated uroflowmetry was defined as a bell-shaped curve with maximum flow more than 15 ml per second and post-void residual urine less than 50 ml. Urodynamic obstruction was diagnosed based on maximum urine flow less than 12 ml per second and maximum detrusor pressure at maximum flow more than 25 cm H(2)O.
Results: In our stress urinary incontinence population the prevalence of urodynamic obstruction was 15.7%. In urodynamically obstructed women storage symptoms were most common (56.3%), while voiding and post-micturition symptoms were less common (31.3% and 6%, respectively). A good correlation between abnormal nonintubated uroflowmetry and urodynamic obstruction (phi = 0.718, p <0.0001) was found. lower urinary tract symptoms correlated weakly with urodynamic obstruction. The diagnostic performance of abnormal nonintubated uroflowmetry for predicting urodynamic obstruction showed that it had relatively low positive predictive value (51.8%) with high negative predictive value (97.3%), sensitivity (87.5%) and specificity (84.1%). The diagnostic performance of lower urinary tract symptoms was weak.
Conclusions: Our study confirms the coexistence of obstruction and stress urinary incontinence. In this population abnormal nonintubated uroflowmetry cannot always confirm the presence of urodynamic obstruction and complete urodynamic study might be indicated. Conversely normal nonintubated uroflowmetry seems to accurately predict normal urodynamic study and might render the execution of this test not essential. Symptoms represent a poor clinical indicator of voiding disorder.