A system of practical medicine. By American authors. Vol. 4

by Unknown

Above the point of obstruction the ureter and pelvis are found dilated and the walls somewhat thinned. The kidney and its pelvis form a more or less irregular rounded pouch, with the tense cylindrical tube of the ureter attached to it below. The kidney itself becomes in various degrees atrophied. In some cases it retains nearly all its secreting structure, and is merely spread out upon the surface of the sac; in others, while the pelvis is but little dilated, the true kidney substance atrophies almost completely, and becomes a mere shell enclosing a cavity continuous with the pelvis and broken up by fibrous septa into subordinate cavities representing the original calices. A partial hydro-nephrosis is sometimes observed affecting only the calices.

Whether the one or the other of these conditions shall result depends, as has already been remarked, upon the completeness and suddenness of the obstruction. If the ureter of a rabbit is ligatured, the second condition—that is, atrophy of the kidney with but little dilatation—is observed. The pressure of urine soon puts a stop to further secretion, and there is no time for a slow and gradual dilatation of the pelvis and ureter. When, as is much more frequently the case in the human subject, the obstruction is more gradual or incomplete, the back pressure is for a long time insufficient to completely stop the passage of fluid through the renal capillaries, so that the pelvis and ureter, though allowing their contents to pass out only under a considerable vis-a-tergo, have time to accommodate themselves to the change, and dilate gradually, attaining sometimes enormous dimensions. The size of a hydro-nephrotic sac varies greatly: 60 liters of contents is certainly a very extreme case.

The sac is usually white and glistening, thinner at some places than at others, and lined with a smooth, pale, and atrophied mucous membrane. The muscular layer has degenerated, and perhaps partly disappeared. The liquid contained in the sac, supposing no inflammatory products to have been mingled therewith, is at first nearly identical with urine, and always contains urea. Afterward its character changes from the absorption of the urinary salts and the secretion of mucus. The contents may be dark-colored from hemorrhage or somewhat gelatinous. At a later period again they become serous and may contain cholesterin.

The description just given, as well as that of the symptoms, applies to simple hydro-nephrosis. When the sac has become inflamed we have the very common combination with pyelitis, and the affection is called pyo-nephrosis. The progress of a case of hydro-nephrosis may be in rare cases to recovery by spontaneous re-establishment of the permeability of the ureter. In others it persists a long time without giving rise to trouble. If inflammation supervene, it is obvious that fever, either simply irritative or of pyæmic character, may be a severe or even a fatal concomitant, or that in this condition a perforation may take place. When the tumor is large it may from its bulk alone produce disturbance of the circulation, dyspnoea, palpitation, and oedema of the lower limbs.

As regards the influence of this lesion on the secretion of urine, everything must depend on the amount of renal atrophy. A single kidney may undoubtedly be completely atrophied by this as by any other lesion without producing serious symptoms, since, as has been repeatedly demonstrated, the other is sufficient to carry on the work under ordinary circumstances; but if, as very frequently happens, both kidneys are involved, there must come a time when the renal substance no longer suffices, and the usual results of suppression of urine follow. It is possible, however, for extensive changes to take place in both kidneys before symptoms of insufficient secretion arise.

Hydro-nephrosis, in the entire absence of inflammatory symptoms and in the presence of conditions likely to cause it known to exist in the lower urinary passages, may be rather suspected than diagnosticated until the appearance of a tumor. Some dull pain in the loins without irradiations in any direction may exist, but so common a symptom can have but little weight in diagnosis. For an early recognition of swelling in suspected cases where nothing can be felt anteriorly, it has been recommended that the patient be placed upon the hands and knees, when the flank upon the affected side, instead of falling slightly forward and leaving a shallow depression outside of the erector spinæ, will remain full or protuberant. When an enlargement evidently connected with the kidney makes its appearance after obstruction to the passage of urine is known to exist, the diagnosis may often be very simple; but if the tumor be the first phenomenon observed, as may easily happen when the obstruction is situated high up or even at the commencement of the ureter, it may require to be distinguished from several other kinds of tumor occupying the lumbar region, or, since hydro-nephrosis of a movable or misplaced kidney sometimes takes place, from tumors of the abdomen in general. From solid malignant tumors of the kidney the feeling of comparative elasticity and fluctuation will in most cases distinguish it, though an encephaloid kidney may be so soft as to render the second of these points of comparatively little value. Absence of hæmaturia and of the cancerous cachexia, though not conclusive, would have much weight.

A hydatid cyst might counterfeit a hydro-nephrosis, but instances of this affection having its primary seat in the kidney are of extreme rarity. An ordinary cystic kidney is most likely to be connected with chronic diffuse interstitial nephritis, which will have made itself manifest by the usual symptoms, and is moreover unlikely to attain the dimensions of a large or even moderate hydro-nephrosis. In a thin person the ureter might, if felt dilated through the abdominal walls, clear up the diagnosis. Extreme cases of cystic kidney with comparatively little nephritis may, however, present great similarity and cause difficulty in diagnosis.

From most other tumors of the abdominal cavity those of the kidney present the important distinction that they are situated behind the peritoneum, and consequently behind the intestines, so that the surface of a renal tumor is likely to be crossed by a more or less extensive area of percussion resonance, representing usually the large intestine. This criterion is, however, not absolute, since a renal tumor may push the colon completely to one side, or, on the other hand, tumors not connected with the kidney may allow the intestine to come between themselves and the abdominal wall.

An ovarian cyst is more manifestly attached to the pelvis, and its history will disclose the fact of its having arisen from below. A gravid uterus should also, when small, be manifestly connected with the pelvis, and when larger be accompanied by the usual symptoms of pregnancy. The same may be said of extra-uterine pregnancy, which may be mentioned as among the conditions possibly giving rise to difficulties in diagnosis.