Rupture may be produced in various ways. It may be by a direct wound, by fracture of the pelvis, by injuries during parturition. Then ulceration not infrequently produces perforation, ulceration from stone on rare occasions, but most frequently the ulceration of a cancer.
The normal urinary bladder may be ruptured by a blow or fall when it is distended with urine. This occurs most readily in intoxicated or insane persons. The rupture occurs usually on the posterior aspect near the fundus and into the peritoneum.
These conditions are important chiefly in their consequences, leading, as they commonly do, to extravasation of urine and to the formation of fistulous communications with the surface or with neighbouring canals.
Simple Extravasation of urine is not in itself serious. The normal urine is a bland fluid, and it may flow from a severed ureter or a ruptured bladder into the peritoneal cavity without producing any peritonitis, the urine being absorbed by the peritoneum and again excreted by the kidney. If the aperture remains open then the secreted urine is not removed, but passes back into the peritoneum to be re-absorbed. In this way a vicious circle is established, and death from Uraemia is the result. The normal urine does not produce an ordinary peritonitis, but it may lead to a considerable serous exudation, and there are the general symptoms of peritonitis.
When the extravasated urine undergoes alkaline decomposition it acquires excessively irritating characters. The urine being an exceedingly decomposable fluid, and being kept at the temperature of the body, rapidly decomposes if the proper organisms find access to it. Hence from rupture into the peritoneum we may have violent acute peritonitis, or from rupture either of the bladder or urethra into the surrounding connective tissue an acute suppurative inflammation of the areolar tissue and skin, sometimes with extensive necrosis.
Fistulous openings from rupture of the bladder may be into the uterus or vagina, into the rectum, or on to the cutaneous surface. From these fistulse the urine passes involuntarily as it reaches the bladder, there being no sphincter to retain it. They occur also as a result of perforation of the bladder from without, especially from the uterus and vagina, the cause of perforation being sometimes cancer of these parts, sometimes sloughing from injury during parturition.