Vicarious Excretion of Urographic Media

Abstract

The excretion of urographic contrast material by the liver and the subsequent visualization of the gallbladder and gastrointestinal tract were common observations before the introduction of the diatrizoate salts. The gallbladder was opacified in 50 per cent of normal patients after the intravenous injection of 25 cc of 70 per cent Urokon (8). This was most likely related to the high protein-binding activity of Urokon (6). The present water-soluble opaque materials do not follow this excretory pathway; the detection of contrast material within the gut represents an alternative excretory route in the person with severe renal disease. An occasional mention of the vicarious excretion of the present groups of contrast material has appeared in the literature (2, 4, 5). In all the cases there was marked reduction in the visualization of the urinary tract at intravenous urography together with impairment of renal function. The report of a patient (1) with normal renal function and vivid biliary excretion raises the question of the substitution of intravenous cholangiographic material for the noted Hypaque. Until recently the doses of radiopaque material used (25 cc or less) may well have been too small and the radiographic density of this material too low for it to be identified in the gallbladder or bowel. Today, with increased quantities of contrast material used in routine urography and with the infusion technic, up to 70 g of iodine has been injected. Thus, opacification of the alternative pathways of excretion is more likely to be recorded. Material and Results Initially, infusions were carried out in patients with normal urinary tracts (Group I) in order to better delineate the pelvocalyceal structures. Films at twenty-four and forty-eight hours were obtained in addition to the five - and twenty-minute roentgenograms. None of these studies showed vicarious excretion, and therefore the hepatic and enteric route is definitely not a course of excretion that is detectable on the roentgenograms of normal subjects, even with the high doses of contrast medium used in the infusion technic. Isotopic studies have shown less than 1.0 per cent biliary and small-bowel excretion of Hypaque 50 per cent in the normal person (3). A group of patients (Table I) with renal disease (Group II), a blood urea nitrogen greater than 50 mg per 100 cc, or poor to non-visualization of the urinary tract (with a dose of 60 cc of contrast material) at lower urea nitrogen levels underwent infusion with either 150 cc of methylglucamine diatrizoate (in the form of Renografin 60) or a combination of sodium (30 per cent) and methylglucamine diatrizoate (60 per cent) (in the form of Hypaque 90), and films of the abdomen were obtained up to forty-eight hours after injection. The colon contents were opacified in all patients (Fig. 3), and the gallbladder in 2 (Figs. 1 and 2).