The role of uroflowmetry in diagnosis of infravesical obstruction in the patients with benign prostatic enlargement.

OBJECTIVE Determine sensitivity and specificity of uroflowmetry in the diagnosis of clear defined outlet obstruction in the patients with benign prostatic enlargement (BPE). MATERIALS AND METHODS 102 patients with proved BPE, after fulfilling International Prostatic Symptom Score (I-PSS), underwent complete urodynamic measurements (uroflowmetry, cystometry and pressure/flow studies). The patients were dichotomized in obstruction zone or out of obstruction, according to the models presented in the literature, but also with combination of Schafer and URA nomograms. Then sensitivity and specificity of uroflowmetry (with cut-off point of Qmax < 10 ml/sec) to the obstruction were determined, as well as to the level of I-PSS. RESULTS 52 patients (51%) had Qmax < 10 ml/sec. T-test has shown that noninvasive variables (age, level of I-PSS, volume of prostate, volume of post void residual or voided volume) differ among the patients of two observed groups (p < 0.05). Discriminant validity of Qmax < 10 ml/sec for diagnosis of clear defined urodynamic obstruction (combination of URA and Schafer nomograms) is calculated by ROC curve, with excellent area of 0.92 (p < 0,00001). According to the levels of I-PSS, the patients were trichotomized. Increase of uroflowmetry sensitivity and specificity to the obstruction by increment of symptoms is noticed. Post-test probability (accuracy) for Qmax < 10 ml/sec to the obstruction for the patients with mild symptoms was 84%, while the same test in the groups of the patients with moderate and severe symptoms were 93% and 95%, respectively. CONCLUSION Value of uroflowmetry, as non-invasive tool in the diagnosis of outlet obstruction is enhanced by accurate defining of obstruction, but also with increase of the lower urinary tract symptoms. By this mean, clinical decision making in the treatment for the individual BPE patient is easier.