Analysis on the Correlation Between Transition Zone Index and Bladder Outlet Obstruction Caused by Benign Prostate Hyperplasia

Yu, Jeong Woo; Lee, Kyoung Rae; Lee, Kun Chul; Lee, Jeong Gu

Abstract

PURPOSE: Prostate volume has been poorly correlated with various parameters used to assess benign prostate hyperplasia (BPH), including symptom score, total prostate volume, peak flow rate and postvoid residual urine. The purpose of this study is to determine if measurement of the volume and the index of transition zone of the prostate correlated well with other clinical parameters in predicting the degree of obstruction.
MATERIALS AND METHODS
121 men with lower urinary tract symptoms were prospectively evaluated using international prostate symptom score, transrectal ultrasonography, and urodynamic investigation with pressure-flow studies for BPH. Bladder outlet obstruction was defined as the maximal detrusor pressure was greater than 40cmH2O at peak flow and peak flow rate was less than 10ml/sec. Patients were then divided into obstructive and non-obstructive groups. Correlations were evaluated among the total prostatic volume (TPV), transition zone volume (TZV), transition zone index (TZI=TZV/TPV) and other clinical and urodynamically obstructive parameters.
RESULTS
Age, IPSS, peak flow rate and PVR were not significantly different between obstructive (n=69) and non-obstructive (n=52) groups. Among the transrectal sonographic parameters, TZV and TZI correlated better with urodynamically obstructive parameters such as detrusor pressure at peak flow rate (r=0.551, 0.544), Abrams Griffiths number (r=0.576, 0.506) and linear passive urethral resistance relation (r=0.560, 0.580) than with TPV. There were no correlations between clinical and volume parameters. All the volume parameters of the prostate were larger in obstructive than in non- obstructive group.
CONCLUSIONS
In patients with BPH symptoms, TZV and TZI correlates better with urodynamically obstructive parameters than did the total prostate volume. TZV or TZI may serve as more useful method for evaluating obstruction.