Limitations of transperineal ultrasound-guided prostate biopsies

Objectives. Screening and diagnosing prostate cancer in men who have undergone abdominoperineal resection (APR) poses a diagnostic challenge. Transperineal ultrasound is an effective imaging technique, but the sensitivity of transperineal needle biopsy under ultrasound guidance has not been evaluated. We compared the results of transrectal ultrasound-guided (TRUS) biopsies and transperineal ultrasound-guided (TPUS) biopsies obtained from patients with known prostate cancer, to evaluate the accuracy of TPUS prostate biopsies. Methods. Twenty patients with prostate cancer diagnosed by TRUS-guided biopsies were studied. Immediately before radical prostatectomy, TPUS was performed in the lithotomy position and six TPUS-guided biopsies were obtained. Routine sextant TRUS-guided biopsies were then obtained. Finally, radical retropubic prostatectomy was performed and the results of both biopsy sets were compared with the pathologic features of the surgical specimen. Results. All 20 prostates contained adenocarcinoma. The prostate was well visualized with TPUS and TRUS in all cases. TPUS-guided biopsies detected cancer in only 2 of the 20 specimens, yielding a sensitivity of 10%. On the same specimens, TRUS-guided biopsies were positive in 13 of 20 cases, a sensitivity of 65%. Cancers detected by TPUS-guided biopsies tended to have a higher volume, higher Gleason grade, and higher prostate-specific antigen level than those not detected by TPUS-guided biopsies. Conclusions. TPUS- guided sextant biopsies are less accurate than TRUS-guided sextant biopsies in detecting prostate cancer, even in the hands of experienced ultrasonographers. The limitations of TPUS-guided needle biopsies emphasize the importance of screening for prostate cancer before APR.