Evaluation of seminal vesicle characteristics by ultrasonography before and after ejaculation.

Twenty males underwent transrectal ultrasonography before and after ejaculation to examine possible alterations that could influence interpretation of seminal vesicle ultrasonography. The preejaculation length of 35 mm was significantly (p < 0.05) decreased to 30 mm after ejaculation. The mean width of the seminal vesicles was 13 mm before and 11 mm after ejaculation. The seminal vesicle volume was significantly diminished after ejaculation (p < 0.05). It therefore seems important to maintain a period of abstinence when evaluating the seminal vesicles by ultrasonography.