The term median bar in prostatic obstruction should be applied to any obstruction involving the posterior vesical lip, unassociated elsewhere with obstruction in the prostate, bladder or posterior urethra. It was originally described in 1830 by G. J. Guthrie, who then called it a dam or bar of the prostate. Later on, Alexander Randall, after an exhaustive pathologic study of prostates, found the term "bar" to be pathologically and anatomically correct.
Median bars can be acquired or congenital in origin and they usually occur at an earlier age than do hypertrophies. But one must not be misled by this early appearance, for in a recent review of 355 cases Young found 208 median bars in men over 50 years of age.
The etiology of most bars is primarily infection of the prostate and seminal vesicles, which results in a fibrosis and contracture at the prostatic neck. This evidence would seem
WILHELMI OJ. CONGENITAL MEDIAN BARS OCCURRING IN TWINS. JAMA. 1933;101(11):847–849. doi:10.1001/jama.1933.02740360027009