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

by Unknown

Variations in the number of the kidneys possess this point of practical interest, that diseases affecting a single organ are more dangerous than if another exists which can take upon itself extra duty. Apparent absence of one kidney may be due to atrophy, attended with very small size of the renal vessels; in which case a small mass of connective tissue is found at the upper end of the ureter, which is usually illy developed. The other kidney is usually hypertrophied.

The kidney may fail to be developed. In this case there are no vessels corresponding to the renal artery and vein, and the ureter is stated to be invariably absent, but the writer has seen a specimen where the left ureter terminated superiorly in a rounded cul-de-sac, no kidney or suprarenal capsule being present. The other kidney was of rather large size in proportion to the size of the patient, but of the usual form. This defect is apt to be associated with some anomaly of the genital organs.

Another condition, apparently similar, but really due to a fusion of the two embryonic kidneys, is sometimes found. In this the single organ, situated upon one side, is irregular in form and in the number and origin of its vessels. There are usually two ureters, arising one above or beside the other, and directed to their proper positions in the floor of the bladder. A single ureter arising from a single kidney has been seen to empty upon the opposite side of the bladder.

Supernumerary kidneys have been noted. In one case an extra pair, situated below the others, were intensely inflamed, while the normal organs were not so.

A position of one kidney has been noticed considerably higher than normal, so as to push the spleen from its place. A more common anomaly, however, is the situation of one kidney at a point much below the usual, most commonly at the brim of the pelvis. When this happens the kidney itself is usually more or less distorted in form, and receives its blood-supply from several small arteries which enter it at irregular points, forming as it were several small hiluses. They may originate from the aorta or from one or both iliacs. The ureter is correspondingly short. This position is of some importance, since a pelvic tumor is formed which has in one instance proved an obstacle in childbirth, while in another the misplaced kidney itself underwent an acute nephritis from the pressure of the foetal head. The kidney tumor has in a few instances been felt in this position during life, but its nature has not been diagnosticated.

Floating Kidney.

The most clinically important change in the position of the kidney is not a permanent one, but varies from time to time with the posture of the patient and the altered conditions of pressure—externally by dress or apparatus, or internally by the other abdominal organs. It is known as floating or wandering kidney. In this affection the kidney ceases to be firmly imbedded in the fat usually found in the lumbar region, constituting a support and packing for these organs as well as for the suprarenal capsules, and is allowed more or less liberty of movement, which is restrained by a pedicle consisting of the ureter, vessels, and nerves, with more or less connective tissue. As it passes downward and forward it comes into more intimate relations with the peritoneum, which usually covers only the anterior surface, often with an intervening layer of fat, so that it may even gain a sort of special investment or meso-nephron.

The extent of the excursions of which the tumor thus formed is capable must naturally vary considerably. Sometimes the organ can be pushed or make its own way forward so as to come into contact with the anterior abdominal wall on the same side, and not much lower than the normal position, or it may pass considerably downward, and thus be confounded with tumors arising from the pelvis.

This affection is much more frequent among women than in men, and the right kidney is more frequently movable than the left: both, however, are sometimes dislocated. It is observed in a much larger proportion of cases in the laboring classes than in those whose work is less severe and carried on in less constrained attitudes. Judging from the relative amount of the literature of the subject, it would appear to be much less frequently observed in this country than among the lower classes of Germany, where so large a proportion of the severest outdoor labor is carried on by women.

Various causes are assigned for this displacement. It is stated to be usually congenital, but is not described as found post-mortem in children with at all the frequency that it occurs in adults; and it is certainly possible in adults to fix in many cases the beginning of the disease with a reasonable degree of certainty. That a certain amount of predisposition, or peculiarly favorable position of the kidney, or an unusual laxity of connective tissue, exists in a certain number of cases is undoubtedly true.