Clinical prostate score for diagnosis of bladder outlet obstruction by prostate measurements and uroflowmetry

To establish a clinical prostate score based on the parameters of uroflowmetry and prostate measurements to provide a better prediction of benign prostatic obstruction (BPO) in men with lower urinary tract symptoms (LUTS) and small prostate volume.

From October 1997 to September 1998, a prospective study of 324 consecutive men with LUTS was conducted in a community hospital in Taiwan. All patients were first evaluated by uroflowmetry and transrectal sonography of the prostate, and a videourodynamic study (VUDS) was performed before any medication was given. Patients were grouped as obstructed or unobstructed according to the results of the VUDS. Parameters from uroflowmetry and prostate measurements were evaluated for their sensitivity in predicting BPO. A clinical prostate score was established by summing scores on seven prostatic and uroflowmetric items: maximal flow rate (Qmax), flow pattern, voided volume, residual urine amount, total prostate volume (TPV), transition zone index (TZI), and prostatic configuration. Each of these items had a score representing the grade of sensitivity of BPO.

Among the 324 men examined, only 65.4% were found to have obstruction by VUDS. A value of Qmax 10 mL/s or less had a sensitivity of only 75.4% and specificity of only 63.7% for BPO. A constrictive flow pattern had 87.2% sensitivity, residual urine 100 mL or greater had 86.1%, TPV 40 mL or greater had 94.6%, TZI 0.5 or greater had 87.8%, and the presence of a median lobe had 87.1% sensitivity; the presence of any of these factors added 2 points to the score. The other parameters were scored as 1, 0, and -1, representing their sensitivity as slightly superior or inferior to that of LUTS. A prostate score of 3 or greater had a sensitivity of 87.2% and a specificity of 60.8% for BPO. On the basis of this prostate score, 148 patients (46%) would have been treated for BPO without the need for further investigation, of whom 19 (5.9%) would have been misdiagnosed. The remaining 176 patients (54%) would have undergone a VUDS and 93 of these patients (28.7%) were unobstructed.

By combining uroflowmetry and transrectal sonography of the prostate, patients with LUTS can be diagnosed with a good sensitivity and specificity. Using the parameters in the uroflow and prostate measurements, a prostate score could be established and used as an indicator of BPO for selecting patients with LUTS who require further treatment or invasive VUDS.