Background: Ultrasound (US) is increasingly used for the detection of prostatic cancer, yet its specificity is low when used alone. A study was undertaken to examine the factors affecting the specificity of prostatic US.
Methods: Thirty-five intact prostates obtained at autopsy were studied in vitro by US, and the findings were correlated with those in histologic sections.
Results: US abnormalities were noted in 24 cases, but prostatic adenocarcinoma was diagnosed by US in only 5 of 12 proven cases. It appears that the US diagnosis of tumor is determined more by location than by size. Anterior and central tumors often are missed by US. Benign prostatic hyperplasia, which affects the transition zone, contributed to a false-positive or false-negative diagnosis of tumor in 10 of 35 cases. Other findings associated with abnormal US include abscesses, infarcts, and seminal vesicles embedded in the prostate.
Conclusion: The specificity of prostatic US is low; it should not be used as an isolated test in screening the prostate for tumors.