Does digital rectal examination predict prostate volume greater than 30 mL?

OBJECTIVES: To investigate the accuracy of digital rectal examination in estimating prostate volume in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia. METHODS: A community-based study was carried out in Japan to investigate the prevalence of lower urinary tract symptoms suggestive of benign prostatic hyperplasia. A total of 457 men were screened and deemed eligible for the present analysis. Findings on digital rectal examination were compared with prostate volume measurement by transrectal ultrasound. Five groups were identified on digital rectal examination: flat, normal, slightly enlarged, moderately enlarged and markedly enlarged. RESULTS: The median age and prostate volume were 64 years and 19.7 mL, respectively. Prostate volumes for the flat, normal, slightly enlarged, moderately enlarged, and markedly enlarged groups were 16.4, 18.3, 27.0, 41.9 and 86.3 mL, respectively. There were significant differences in prostate volume between the groups. The positive predictive value was 94.1% if flat, and normal were assumed to have a prostate volume <30 mL. The value was 80.8% if moderately enlarged, and markedly enlarged were assumed to have a prostate volume ≥30 mL. Of the men in the slightly enlarged group, 61.0% had a prostate volume <30 mL. CONCLUSIONS: It is possible to stratify prostate volume according to digital rectal examination. We could determine the prostates in the flat and normal groups to have a prostate volume <30 mL, and those in the moderately enlarged and markedly enlarged groups to have a prostate volume ≥30 mL by digital rectal examination with high accuracy. Transrectal ultrasound was required for those in the slightly enlarged group.