Injuries to the urethra are chiefly important on account of their tendency to lead to stricture. Falls on the perinaeum when sufficiently severe to fracture the pelvis, usually cause rupture of the urethra. This is followed by extravasation of urine, which may lead to serious results. In case of recovery the wound in healing draws together, and leads to stricture, which may even amount to obliteration of the canal.

Injuries are also frequently inflicted from within by the passage of bougies and catheters.

Inflammations

The most frequent form is Gonorrhoea which we have seen to result from the action of the gonococcus (p. 345).. The mucous membrane in the acute stage is red and swollen, and there is a purulent discharge, mixed with blood. The inflammation sometimes extends to the surrounding connective tissue or to the spongy tissue of the penis. There may be abscesses so formed, and in some cases a thrombo-phlebitis occurs, with resulting pyaemia. It may also extend to the bladder. The acute stage passes off and usually leaves a chronic inflammation which frequently results in stricture.

Other forms of inflammation are rare. There may be a simple catarrh, especially in the female urethra, propagated probably from the vagina.

Stricture

Obstruction of the urethra occurs, as we have seen, in consequence of injuries. As it is mostly the membranous part of the urethra which is torn, the resulting stricture has its seat there.

Enlargement of the prostate is the cause of obstruction, but scarcely of stricture of the urethra (see under Diseases of the male organs).

Gonorrhoea is the most frequent cause. The chronic inflammation, which so frequently remains after the acute stage of gonorrhoea, commonly concentrates itself in the most dependent part of the canal, which is the point of union between the membranous and spongy portions or the first part of the spongy portion. Here the mucous membrane remains swollen, and, as the chronic inflammation continues, connective tissue is formed, both in the mucous membrane and for some distance around. The new-formed tissue is, as in other cases of chronic inflammation, dense, and possesses a tendency to contract. Its contraction narrows the canal, which may be found embedded in an exceedingly dense, almost cartilaginous tissue. There is seldom an actual obliteration of the canal, such as occurs more readily in traumatic stricture.

In cases of stricture False passages are frequently formed by the catheter. These have their aperture near the stricture, and after burrowing through beneath the mucous membrane, either join the urethra on the proximal side or pass on to the neck of the bladder before forming a communication.

The urethra is dilated on the proximal side of the stricture, and this dilatation may be propagated to the bladder, and sometimes to the ureters and pelvis of the kidney. Sometimes the dilatation of the urethra, by widening the neck of the bladder, causes paralysis of the sphincter. Hypertrophy of the bladder is a common result of stricture.

Tumours are very rare in the urethra. Carunculne are limited polypoid outgrowths from the mucous membrane, of very rare occurrence. Tuberculosis occurs in association with the same disease of the bladder, prostate and vesiculate seminales. Cancer is met with chiefly in the deep parts of the urethra by propagation from prostate or bladder, and in the distal parts by propagation from the glans penis.