1. Defective Development

The urethra is absent in those rare cases in which the entire uropoietic system is wanting, as also in those in which the bladder is deficient; it is also wanting in those cases in which there is a partial deficiency of the bladder, as in cases of fissure, of ectrophy in the female sex, and of cloacal formation. The urethra may be imperfectly developed, presenting on the upper (epispadiasis) or lower (hypospadiasis) surface of the penis, a fissure which extends either along its entire length, or only to a short distance from the external orifice; fissure of the entire dorsal surface of the penis occurs as a complication of eversion of the bladder, that of the inferior surface with fissure of the scrotum. The latter malformation causes a resemblance to the vagina. In other cases a portion of the urethra is deficient, and the latter then terminates in a cul-de-sac, placed at a greater or less distance from the usual point of the orifice in the glans penis; total absence of the urethra equally gives rise to an imperforate penis.

The urethra may, in consequence of a congenital arrest of development, not open externally, but communicate with the cavity of the rectum, or in the female sex with the vagina; or vice versa, it may receive the rectum or vagina at the lower or posterior portion of its parietes.

2. Deviations Of Size

They affect, with exception of congenital shortness of the urethra, its calibre only. We find a more or less dilated or contracted condition of the urethra occurring in both sexes as a congenital anomaly, and affecting its entire extent or small portions only; it is of especial importance in the male sex.

Dilatations as well as contractions of the urethra, the latter being particularly frequent and important, occur as acquired conditions.

Dilatation affects the entire canal uniformly or detached spots only; this depends upon the locality of a mechanical impediment, and upon the extensibility of various portions of the urethra. The pars membra-nacea of the male urethra is liable to the largest fusiform and pouchy dilatations; a uniform dilatation of the entire canal is often brought on by the continued use of bougies.

Contractions of the urethra originate in primary, but more frequently in secondary, textural changes of the urethral mucous membrane of the corpus cavernosum and its fibrous sheath, and we shall have to examine them more carefully when speaking of urethral inflammation and its consequences.

Contractions of the urethra are also brought on in either sex by the pressure of morbid growths, in man by the enlarged prostate, in the female by neighboring organs that have been dislocated, e. g. the uterus, the prolapsed vagina, etc. The passage of the urethra may also be more or less permanently or dangerously narrowed or closed up by products of its own mucous membrane, as well as that of the bladder, e. g. a mucous plug, croupy exudation, renal and vesical calculi, acephalo-cysts, etc.

3. Deviations Of Direction

Among these we reckon the serpentine, angular or inflected, and variously altered course given to the urethra by voluminous herniae in either sex, by large morbid growths in the vicinity, by the dislocation of neighboring organs (the uterus) in the female, and especially by the enlarged prostate in man; the latter causes a contraction of the urethra, and pushes it aside, or divides it into two passages, which diverge in the direction of the bladder.

Both the pressure which the urethra suffers, as well as the anomalous direction, and particularly the inflection induced, diminish the calibre of the urethra at various points.

4. Solutions Of Continuity

We enumerate under this head, wounds of the urethra, contusions and rupture brought on by a concussion or fall, particularly upon the perineum; rupture produced by the passage of large angular calculi, perforations brought on by rude efforts at catheterization, and ulcerative destruction. In all these cases incomplete recovery very often takes place, leaving urinary fistulae of varying extent, length, direction, and course.