The next most important factor is undoubtedly a laxity of the abdominal walls, affording a less firm and unyielding support to the contained viscera, and a deficiency, usually an acquired one, of the fat surrounding the kidney, which enables it in the normal condition to be supported by the layer of peritoneum passing across its front from the spinal column to the flank. This is seen in a certain set of cases where the trouble dates from an acute disease or a rapid emaciation. The well-known influence of repeated pregnancies is undoubtedly exerted in this way.
Another set, especially those exceptional cases which occur in strongly-built and not thin persons, are referable to severe shocks received in gymnastic exercises, hard riding, or falls from a horse.
One of the most frequent causes, and one which accounts for the fact of the affection being most prevalent among the working classes, is the use of a tight strap or cord to support the garments. Corsets, which exercise a more even pressure over a larger surface, do not have this effect. The right kidney, from the position of its superior extremity in front of the liver and its slightly higher place in the abdomen, appears to be more influenced by this pressure than the left. The movements of respiration, especially when reinforced by the forced inspiration and compression of the abdominal viscera accompanying violent exertion, appear to assist in the dislodgment already favored by the pressure of the girdle.
According to Müller Warnek,3 who has laid especial stress on this method of causation, a slighter degree of displacement is possible in this way without or preceding the full development of wandering kidney. A pressure is exercised upon the descending duodenum with which the right kidney is brought into intimate relations behind, and bound down by, the peritoneum; which leads, as Bartels supposes, to a hindrance in the passage of food from the stomach, and consequent dyspeptic phenomena. In these cases, when the kidney has become a more freely movable one and has dropped farther down in the abdominal cavity, the pressure on the duodenum ceases, the consequent symptoms disappear, and give place to the dragging sensations and severe colicky attacks which are apt to characterize an older case.
3 Berl. klin. Woch., 1877, 38.
SYMPTOMATOLOGY.—There is great variety in the kind and amount of effect which the movable kidney exercises on the general organism and the local effects it produces. Neither the local nor the general symptoms are necessarily proportionate in severity to the amount of the displacement.
It may be said in advance that, contrary to what might be expected, the symptoms are not usually connected with any disturbance in the urinary function, and, although exceptions are not unknown, the rule is for a displaced kidney to be an otherwise healthy one. Cystitis and uterine affections have been observed in this connection, but it is doubtful if any relation other than coincidence or a mutual dependence upon impaired general nutrition and overwork exists between them. The partial stoppages which might be supposed to arise from the twisting of the ureters are not frequently observed.
Hysteria and hypochondriasis have been frequently attributed to this lesion, and might undoubtedly find their exciting cause in anxiety about a tumor of unknown character and origin; but there seems no good reason to connect them in any other relation of causation. It is undoubtedly true that many pains and discomforts exist in these cases which are neither satisfactorily explained nor gotten rid of by being called hysterical. These abdominal pains, especially of a dragging character, and also the sensation as of something falling or moving about in the abdomen, particularly when the patient assumes the upright posture or makes unusual exertions, are very naturally connected with the existence of the actual condition which is likely to give rise to them. Müller Warnek has recorded the frequent coincidence of flatulent dyspepsia and dilatation of the stomach depending on retention, and its consequent fermentation, in connection with the movable kidney and its supposed pressure on the duodenum. It is not probable, however, that all the symptoms are to be explained so simply, but it is quite as likely that the dragging and tension of the pedicle may have a remoter effect through the renal and sympathetic nerves.
Severer attacks occasionally occur with violent colic and inflammatory symptoms, the tumor formed by the misplaced organ becoming exceedingly sensitive to pressure. These have been attributed to some incarceration, but there is no evidence that this accident occurs, and it has not been found after death. They are probably due to a localized peritonitis of the investment of the kidney, or perhaps to simple neuralgia. Icterus and hepatitis, consequent upon a circumscribed peritonitis set up by the pressure of the movable kidney upon the liver, have been observed.
Death is not one of the usual results of this affection, but a recent surgical writer (Keppler4) has called attention to cases where long-continued dyspeptic symptoms, with constant pain and the chagrin and melancholy due to inability to work, have been followed by death from exhaustion, and nothing except a movable kidney has been found at the autopsy.