The Clinical Application of Urinary Dynamics

Abstract

CLINICAL application of intravenous urography makes it necessary to consider normal and pathologic morphology and physiology of the entire urinary tract. Adequate analysis of intravenous urograms necessitates a division of the physiologic activity into secretion, or filtration which cannot be directly visualized, and dynamic excretion, or the transportation of urine which can be demonstrated. Dynamics vary markedly and sometimes almost specifically in various disease entities and emphasis on these variables permits intelligent interpretation and clinical application of the information revealed. The study is best approached by stressing urinary peristalsis. We do not believe this dynamic function can be studied advantageously when compression or other artificial interference is employed. There are unknown physiologic, neurogenic, and anatomic factors which enter into normal renal function and there is some speculation and theorizing as to the mechanism by physiologists, anatomists, and medical writers. Much of this unknown quantity does not readily lend itself to experimental investigation because the very attempt to do so creates an abnormal physiologic state in a highly sensitive system. However, it is helpful to attempt an explanation of some of these factors by a correlation of visualized function and clinical symptoms in the present state of individuals suffering from various urinary diseases and, if possible, to apply them to urographic diagnosis. The source of the stimulus and the point and mechanism of excitation for urinary peristalsis are not known absolutely but the visible contraction begins in the lesser calices about the apex of the pyramids. Neither is it known definitely whether the calices are excited independently at different time intervals or all are excited simultaneously by a single stimulus. Independent excitation at different times is illogical, for this would be at variance with the purposeful regularity of physiologic function, unless the stimulus to contraction is produced by the degree of distention of the calyx. One is not justified in assuming that, because demonstrable movement first occurs about the papilla, this is the trigger point of excitation without adequate proof of such a statement. We believe that the contraction, regardless of origin, is a simultaneously excited unit wave proceeding from the point of excitation through the renal pelvis, and probably to the uretero-vesical orifice, where its purpose is completed. Contraction of the renal pelvis in all directions is easily demonstrable, and the apparent multiplicity of peristaltic waves is probably due to an absence of, and a difference in, the volume of fluid in the component parts of the kidney pelvis, and the smooth muscle adjusts itself to this volume at a given point, at a given time.