Transitional Zone Index: a Predictor of Acute Urinary Retention in Patients with Benign Prostatic Hyperplasia

Lee, Jeong Oh; Seong, In Gi; Han, Bo Hyun

Abstract

PURPOSE: To investigate the efficacy of age, International Prostate Symptom Score(I-PSS), quality of life(QOL) score, various parameters obtained by transrectal ultrasonography(TRUS) as predictors of the onset of acute urinary retention in patients with benign prostatic hyperplasia(BPH).
MATERIALS AND METHODS
From January 1996 to December 1997, 101 men(mean age 70years, range 52-92) with symptoms of BPH were enrolled in this study. Among them, 36 patients had suffered from acute urinary retention. TRUS was used to calculate the total prostate(TP) volume, the transitional zone(TZ) volume, the transitional zone index(TZ index=TZ volume/TP volume). To compare the usefulness of various indices, the area under the receiver-operator characteristic(ROC) curve was calculated for each index.
RESULTS
There were significant differences in age, TP volume, TZ volume, TZ index between patients with and without acute urinary retention, but no significant differences in I-PSS and QOL score. In patients with acute urinary retention, the area under the ROC curve was 0.911 for the TZ index, 0.892 for the TZ volume, 0.769 for the TP volume and 0.660 for the age.
CONCLUSIONS
The TZ index is a useful predictor of acute urinary retention in patients with BPH and may be a useful parameter for decision of surgical intervention.