Transitional Zone Volume: A Predictor of Acute Urinary Retention in Patients with Benign Prostatic Hyperplasia

Chang, Hyuk Soo; Park, Choal Hee; Kim, Chun Il

Abstract

PURPOSE: The objective of this study was to investigate the efficacy of the International Prostate Symptom Score (IPSS) and various parameters obtained from transrectal ultrasonography (TRUS) as predictors of the onset of acute urinary retention in patients with symptomatic benign prostatic hyperplasia (BPH).
MATERIALS AND METHODS
From January 1997 to December 2003, 1,765 patients with symptomatic BPH were enrolled in this study, but not all patients had had previous BPH treatment. Of the 1,765 patients, 323 presented with acute urinary retention. A TRUS examination was performed to calculate the total prostate volume (TPV), transition zone volume (TZV), transition zone index (TZI=TZ volume/TP volume) and elongation ratio (ER=maximal anteroposterior diameter/transverse diameter). Statistical comparisons of the retention (n=323) and non-retention groups (n=1,442) were performed using the Mann-Whitney test, and receiver operating characteristic (ROC) curves of the independent risk factor were obtained to compare the usefulness of various indices.
RESULTS
There were significant differences in the age, TPV, TZV, TZI and ER between the retention and non-retention groups, but no significant differences in the IPSS. The most effective cutoff value was a 15ml TZV. The area under the curves were 0.887 (TZV), 0.884 (TZI), 0.857 (TPV) and 0.736 (ER).
CONCLUSIONS
The TZV is the most useful predictor of the onset of acute urinary retention in patients with symptomatic BPH, with the TZI can also be a useful predictor. The TZV and TZI may be useful parameters when deciding the method of treatment.