Ultrasonographic characteristics of the seminal vesicles after ejaculation.

A total of 12 men from a sperm donor bank underwent transrectal ultrasonography before and after ejaculation to investigate possible changes that could influence interpretation of seminal vesicle ultrasonography. The mean length of the seminal vesicles was 2.98 cm. before and 2.95 cm. after ejaculation. The anteroposterior diameter decreased only from 0.59 to 0.52 cm. Minimal differences were noted between the right and left seminal vesicles, and the greatest variation in size in an individual was only 3 mm. These results indicate that interpretation of seminal vesicle anatomy as seen by ultrasonography does not depend upon the temporal relationship to ejaculation.