Objective. Accurate clinical staging of prostate cancer continues to c
hallenge the urologist, with understaging a common problem. Preoperati
ve identification of men with capsular penetration or seminal vesicle
invasion would allow deferment of radical surgery unlikely to cure the
patient. We investigated the ability of seminal vesicle volume as det
ermined by transrectal ultrasound (TRUS) to predict the stage of prost
ate carcinoma. Methods. Forty-seven consecutive men undergoing radical
prostatectomy had preoperative determination of the seminal vesicle v
olume by TRUS. The volume was determined for each individual seminal v
esicle as well as the total seminal vesicle volume. Asymmetry was defi
ned as one seminal vesicle having twice the volume of the other. Resul
ts. Average total seminal vesicle volume was statistically greater for
patients with Stage C disease as opposed to those with organ-confined
tumors. Seminal vesicle asymmetry was also present statistically more
often in Stage C patients than Stage B men. The combination of total
seminal vesicle volume less than 15 cc and symmetrical seminal vesicle
s yielded a possibility of only 18% of extraprostatic extension of tum
or. Conclusions. We believe that seminal vesicle volume as determined
by TRUS can aid in the staging of adenocarcinoma of the prostate and s
hould be considered along with other parameters, such as prostate-spec
ific antigen, acid phosphatase, and Gleason score, when planning thera
py for this disease.