Prostate-specific antigen and transition zone index - powerful predictors for acute urinary retention in men with benign prostatic hyperplasia.

OBJECTIVES: To examine the efficacy of prostate-specific antigen and various parameters obtained by transrectal ultrasonography as predictors of acute urinary retention in patients with benign prostatic hyperplasia. METHODS: Eighty-nine men with symptoms of benign prostatic hyperplasia were enrolled in this study from February 2002 to June 2003. Among them, 21 patients presented with acute urinary retention. Transrectal ultrasonography was used to calculate the total prostate volume, transition zone volume and transition zone index. Sample of prostate-specific antigen was taken in outpatient clinic or in clinic before first insertion of the catheter into the bladder, because of urinary retention. If the patient presented with inserted catheter, we used latest prostate-specific antigen date from the medical notes of outpatient clinic. To compare the usefulness of the various indexes, the area under the receiver-operator characteristic curve was calculated for each index. RESULTS: There were significant differences between patients with and without acute urinary retention in the total prostate volume (58.16 cm(3) and 44.28 cm(3), p=0.0028), transition zone volume (36.62 cm(3) and 23.70 cm(3), p=0.0001), transition zone index (0.62 and 0.51, p=0.00022), prostate-specific antigen (4.96 ng/ml and 2.97 ng/ml, p=0.00069), age and quality of life score, but no significant difference in International Prostate Symptom Score. In patients with acute urinary retention, the area under the receiver-operator characteristic curve was 0.775 for transition zone index, 0.742 for prostate-specific antigen, 0.737 for transition zone volume, 0.696 for total prostate zone volume and 0.633 for International Prostate Symptom Score. CONCLUSIONS: The transition zone index and prostate-specific antigen are accurate predictors of acute urinary retention in patients with benign prostatic hyperplasia and may be useful for deciding between surgical intervention and medical treatment.