Accurate determination of prostate size via digital rectal examination and transrectal ultrasound.

Previously, prostate size did not play a significant role in the choice of treatment for benign prostatic hyperplasia (BPH). It has been postulated that prostate size does not correlate with symptom severity, flow rate, or the presence or absence of obstruction. However, in a published study of community-dwelling men, the odds of having moderate to severe symptoms were five times higher for men with enlarged prostates than for those with normal prostates. Response to certain types of BPH therapy, especially finasteride, depends on actual prostate volume. Therefore, it is important to have a simple way to accurately determine if a patient's prostate is enlarged. In an analysis of four studies, there was a distinct underestimation of prostate size by digital rectal examination (DRE) when compared with transrectal ultrasound (TRUS) measurement. The underestimation of prostate volume increased with increasing TRUS volume, particularly if the volume was greater than 30 mL. The average underestimation was between 9% and 12% for prostate volumes 30 to 39 mL and between 17% and 27% for prostate volumes 40 to 49 mL. Because of these results, a prospective study is currently in progress to develop models or visual aids to assist physicians in more accurately predicting a threshold prostate volume via DRE.