LOCALIZATION.
The predilection of stricture for different portions of the canal has not been clearly explained by the various authorities upon the subject. The explanation usually given for the relatively greater fre quency of occurrence of stricture in various portions of the canal— more particularly in the bulbo-membranous region—is the presence of a greater amount of erectile tissue, and a more marked tendency to localization of inflammatory processes here than in other portions of the canal.
There are several points to be considered in the explanation of the occurrence of stricture in any particular location, and in some instances there are certain special elements in its production which are worthy of attention.
Acquired stricture at or just within the meatus is favored by the existence of congenital narrowing at this point. There is con stant obstruction to the passage of urine, and the friction thereby induced inevitably enhances inflammation. There is, moreover, a tendency to the accumulation of secretions behind it.
The introduction of the nozzle of the ordinary syringe in inject ing the urethra necessarily produces considerable irritation when the meatus is very narrow. These considerations explain the frequency with which acquired stricture is found just within the meatus.
The relative dilatation of the bulbous portion of the spongy ure thra and of the fosses navicularis undoubtedly favors the retention of a small quantity of urine and of pathological discharges at these points, but this element in the causation of stricture is not very im portant until actual obstruction by inflammatory thickening of the mucous membrane occurs just in front of the dilated point.
When stricture begins to form there will inevitably be a small quantity of urine left in the canal after micturition. The author believes, however, that this condition assumes little importance until the stricture becomes very thick, as the residual urine is not allowed to remain undisturbed for any great length of time.
Strictures produced by injury to the canal during the passage of instruments necessarily occur at the site of the lesion thereby produced. •
Traumatic strictures produced by falls and blows upon the ure thra correspond to the seat of the injury. In the deep and fixed urethra such strictures occur most frequently at the bulbo-membra nous junction, for reasons already stated.
The location of strictures due to the introduction of strong chemi cal and caustic substances into the urethra is at the site of their action. Foreign bodies in the urethra may produce localized inflam mation—and perhaps ulceration—which determines the site of a sub sequent stricture.
Injury incidental to chordee is often responsible for the localiza tion of stricture. This condition interferes with the normal distensi bility and elasticity of the urethra, and during erection produces a strain and perhaps rupture of the corpus spongiosum and urethra at some particular point. This may be produced by the patient forci bly bending the penis. The writer believes that it may result also from frequent and vigorous erections.
By far the most important element in the determination of stric ture is the existence of certain normal anatomical peculiarities of the canal. This is the chief bone of contention among the warring factions whose casus belli is the question, to cut or not to cut.
It has been shown by Weir, Sands, and others that there are cer tain points of narrowing in the spongy portion of the canal which have been termed by them normal contractions, these being distinct from the normal points of contraction usually recognized, namely, the meatus, the bulbo-membranous junction, and the point of union of the spongy urethra with the fossa navicularis. This description is somewhat misleading. The urethra is an elastic tube susceptible of considerable dilatation. Its elasticity, however, is not uniform throughout, but as a consequence of sparsity of elastic tissue, with a preponderance of connective and fibrous tissue in the erectile struc ture of the corpus spongiosum and a deficiency of areolar tissue be neath the mucous membrane, there exists at various points in the canal relative inelasticity and limited dilatability of the urethra.