Papillary opacification in excretory urography, the so-called pyelotubular reflux.

Abstract

Radiologists and urologists are familiar with various types of pyelorenal reflux occasionally observed during retrograde pyelography. After the introduction of ureteral catheterization by Casper in 1895 and of pyelography by Volker and Lichtenberg in 1906, a considerable time elapsed before gross injuries, either by the catheter or by the injected contrast medium, were first recognized and correctly interpreted. Hinman and Lee-Brown, in 1924, investigated these injuries and coined the term pyelovenous backflow or reflux. Only pyelotubular reflux is true backflow. The other types are the result of traumatic rupture, mostly at the calyceal fornix, and have been described as pyelolymphatic, pyelovenous, pyeloparenchymal, subcapsular, and peripelvic reflux or extravasation. These injuries are attributed to the catheter proper or to the increase in intrapelvic pressure during injection of the medium. Olsson in 1948 described similar types of reflux occurring during excretory urography. Since they have been observed in the presence of an obstructing ureteral stone and during or immediately after a colic, and with external ureteral compression, they, too, have been attributed to increased intrapelvic pressure. Olsson specifically excluded from his discussion pyelotubular reflux, but without explaining its nature. This type of “reflux” has been observed during excretory urography with increasing frequency during the past few years. The “staining of the papillae” is often referred to as “sunburst” or “brush-like” opacification (Fig. 1). A faint or moderately dense homogeneous shadow occupies the area of the papilla, fading out toward the base of the pyramid. This shadow is lighter than that of the concentrated contrast medium in the corresponding calyceal cup. Usually all papillae of a kidney are thus stained in about equal density; occasionally the “brushes” are more conspicuous in some pyramids than in others. A difference in degree is also seen on comparison of the right and left kidneys in certain urographic studies. It has been fairly general practice to perform excretory urography with application of external compression in order to delay the urinary flow, promote stasis in the ureters and renal pelves, and thus increase the concentration of the contrast medium. I t was postulated that stasis in the renal pelvis, with resultant increased intrapelvic pressure, might cause urinary outside into the papillae and tubules of the pyramids in retrograde pyelography. Since, however, the renal pelvis is known not to have a concentrating capacity, it is not at all clear why a solution forced back from the renal pelvis into the papillary ducts and collecting tubules could opacify stasis in the collecting tubules also, thus producing impregnation of the papillae (Olsson, Bauer, Sengpiel, Hinkel). Such an explanation, however, leaves several questions unanswered.