Invasion of the seminal vesicles by prostatic cancer: detection with transrectal sonography

Endorectal sonography provides a potential means of detecting seminal vesicle invasion by prostatic cancer that is too subtle for diagnosis by digital rectal examination. To assess this application of sonography, we examined 300 patients with transrectal sonography of the prostate and seminal vesicles followed by histologic examination of the seminal vesicles from core biopsies and/or prostatectomy specimens. Of the 38 patients with histologically proved seminal vesicle invasion by prostatic cancer, 35 (92%) had an abnormal appearance of the seminal vesicles on sonography. Of 167 patients with prostatic cancer without histologic evidence of seminal vesicle involvement, sonograms showed abnormal seminal vesicles in 42 (25%). In 95 patients with histologically normal prostates and seminal vesicles, sonograms showed abnormal seminal vesicles in 11 (12%). The sonographic findings correlating best with tumor invasion of the seminal vesicles were hyperechogenicity and a combination of two or more of the following abnormalities: cystic dilatation, asymmetry, enlargement, and anterior displacement. Our experience in these patients suggests that endorectal sonography can be useful in the detection of seminal vesicle involvement by prostatic cancer.