1. Defect And Excess Of Formation

It is self-evident that where one kidney is deficient, the corresponding portion of the urinary passages must be entirely, or at least partially, absent; but when the kidneys are present, exceptional cases occur in which the ureters terminate in a cul-de-sac in the vicinity of the bladder, and also in the neighborhood of the pelvis of the kidney; or we may find in addition to a perfect ureter, a rudimentary one developed at the bladder; or finally, the apparatus may have undergone an arrest of development, and be very narrow, and have very delicate coats.

If the kidneys are increased in number, the urinary channels are also multiplied; but more frequently the apparent excess is owing to fissure; the calices opening into two or three pelves, which, in their turn, discharge themselves into two or three ureters. In a less marked degree there is a single pelvis, which is divided inferiorly so as to open into two ureters; occasionally, these are also found to form partial subdivisions. This malformation, and particularly the fissured pelvis, which is then found partially detached from the organ, frequently accompanies a defective development of the hilus of the kidney; it also coexists with an elongated state and a transverse division of the kidneys.

The relation of the vesical orifice of the fissured ureters to the bladder varies. They generally coalesce in the neighborhood of the bladder, or within its coats, so as to form a single channel, which communicates with the cavity of the bladder by a single mouth; they rarely open by separate orifices placed behind one another at one side of the trigonum Lieutaudi.

When the kidney occupies an irregularly low position, the length of the ureter is correspondingly diminished.

2. Deviations Of Calibre

The deviations of calibre consist in dilatation of the urinary passages, caused by accumulations of urine, which result from obstacles to its discharge, and frequently favored by an inflammatory condition of the mucous membrane, which paralyzes the external contractile layer. It will depend upon the position of the impediment whether the dilatation affects a larger or smaller section of the apparatus. If the former occupies the vesical orifice of the ureter, the entire ureter, the pelvis, and lastly, the calices, become gradually dilated; it is evident, as we shall subsequently examine more fully, that more distant impediments, as, for instance, those placed in the urethra, must also induce dilatation.

The degree in which the dilatation occurs is very various; the higher degrees offer on their own account, as well as on account of various consecutive anomalies, numerous points of interest. Dilatation of the pelves and calices, by exerting pressure upon the renal substance, induces atrophy of the latter. The papilla is first reduced; it becomes condensed and coriaceous, and gradually disappears in the arch of the expanded calyx; the superimposed renal tissue at the same time diminishing in thickness, becoming denser, and assuming a leathery toughness. At an advanced stage the substance of the kidney may be only one, or a few lines in thickness, and even disappear altogether, being converted into a mere membranous sac (hydrops renalis, Rayer's hydronephrose), with an external lobulated appearance, presenting cells within, and filled with a urinous, variously sedimentary fluid, or with clear serum; the loculi may intercommunicate with one another, in consequence of atrophy or rupture of the contiguous parietes. These sacs sometimes attain, especially in cases which are unaccompanied by inflammation, the size of a child's or an adult's head; but there is no doubt that, after the urinary secretion has ceased, in consequence of atrophy of the renal tissue, and especially of previous inflammation, they may be reduced.

Dilatation of the ureters exhibits every possible degree; the ureter may even attain the size of the small intestine. It is then found hyper-trophied, inasmuch as its parietes not only present the average but even increased thickness; and as it is increased in length, and consequently, instead of being straight, appears coiled or bent. At the same time the dilatation is not uniform, as several portions of the ureter are narrower than others, the external cellulo-fibrous tissue accumulating at these points during the dilatation, and offering resistance. To this fact, also, is owing the peculiar direction the ureter assumes, as the curvature or flexure always occurs at these spots. It may also be observed that the tube rotates upon its axis at these points, a circumstance which further adds to the diminution of its calibre, and offers a new obstacle. The parietes of these cavities and canals always bear, as we have already remarked, that proportion to the dilatation, that they must be considered hypertrophied; they only attain a remarkable and extravagant thickness, however, if there is concurrent inflammation.

The following circumstances may induce the occurrence of dilatation: Compression of the ureter at different points by morbid growths, by the impregnated uterus, especially by cancer of the womb which extends to the bladder, by fibroid tumors of the uterus, by enlarged, and particularly by dropsical, ovaries, by accumulation of urine in the bladder itself, or by lasting contraction of the bladder consequent upon hypertrophy of its coats; - contraction of the ureter from tumefaction of its coats, consequent upon inflammation and its results; - obliteration of the ureter, and obturation of the calices, the pelvis, and ureter, by calculous concretions; - cancerous growths forcing their way inwards from without; and, finally, numerous morbid conditions of the bladder, the prostate, and the urethra, which impede the discharge of the urine into the bladder, or the evacuation of the latter.

These dilatations are consequently generally acquired in advanced life, though in the case of original occlusion (blind termination) of the urinary passages, they may be congenital.

In a particular case that we have observed, the pressure exerted by an irregular branch of the emulgent artery, of one line in diameter, that descended from the upper end of the hilus, so as to form an arch over the convoluted transition of the pelvis to the ureter on the right side, caused a dilatation of the former.

The contractions of the urinary passages are sufficiently explained in the above; they are also the result of renal atrophy, and may amount to complete obliteration and closure of their calibre.

3. Anomalies Of Position

As a congenital anomaly, we mention the detached position of the single or multiplied pelvis of the kidney accompanying an imperfectly developed state of the renal labia, and especially occurring in cases of anomalous formation and position of the kidney: acquired anomalies of position are brought on by pressure exerted upon the ureter by irregularities of the neighboring organs.