[The prediction of bladder outlet obstruction with prostate volume, maximum flow rate, residual urine and the international prostate symptom score in patients with lower urinary tract symptoms].

We determined whether prostate volume (PV), maximum flow rate (Qmax), residual urine (RU) and the International Prostate Symptom Score (I-PSS) predicted bladder outlet obstruction in patients having lower urinary tract symptoms (LUTSs). The study consisted of 114 patients aged 50 years or older with LUTSs who had scores of 8 or more on the I-PSS and 2 or more for the quality of life index. All patients received transrectal ultrasonography for estimation of PV and pressure-flow study (PFS). When PFS showed an obstruction grade of 2 or more in Schäfer's p/Q diagram, the result was defined as bladder outlet obstruction. When we examined which criteria indicated that 90% of patients had bladder outlet obstruction (positive predictive value: 90%), we found that PV of 35 ml or more, Qmax of 8 ml/sec or less, RU of 110 ml or more, and I-PSS of 30 or more did so. Fifty-nine percent of patients met at least one of these criteria. The results suggested that 59% of patients with LUTSs had bladder outlet obstruction with a 90% positive predictive value based on the value of PV, Qmax, RU or I-PSS.