Unreliability of International Prostate Symptom Score (IPSS) and Residual Urine for the Evaluation of Bladder Outlet Obstruction (BOO)

Abstract

Background: Object of this study was to assess the reliability of the symptomatology and
residual urine in assessment of bladder outlet obstruction (BOO) due to benign prostatic
enlargement (BPE).
Methods: Flowmetry of patients with IPSS greater than 20 and normal residual urine (<100ml)
was done. Patients above age of 50 with International Prostate Symptom Score (IPSS) > 20,
residual urine < 100 ml and voided volume > 150 ml were included. Those with stricture urethra or
TURP were excluded. Study parameters were age, residual urine, maximum flow rate (Qmax),
average flow rate (Qave), flow time and voided volume. SPSS version 15 was used for statistical
analysis.
Results: Out of 41 (mean age 64.3 years ± 8.49), 17 (41%) were found to have obstruction on the
basis of Qmax, Qave, flow time, and flowmetry tracings. Among the obstructed patients, Pearson
correlation between voided volume and Qmax was (r=0.322, p < .05) while it was (r=-0.528, p=
.117) between Qmax and residual urine.
Conclusion: Assessing on residual urine and symptomatology alone would have
misdiagnosed 41% and 59% patients respectively.. Therefore IPSS or residual urine alone is not
satisfactory and patients should be assessed by combining IPSS, residual urine and
uroflowmetry.