Vicarious contrast media excretion (VCME) refers to the excretion of intravascularly-administered water-soluble iodinated contrast media in a way other than via normal renal excretion. More rarely it may occur following oral contrast medium administration ⁶.

Epidemiology

The most common vicarious excretion of water-soluble contrast material is via the liver, resulting in increased bile density seen in the gallbladder. It can also occur via the small bowel or into ascitic fluid ³.

Pathology

Although commonly associated with obstructive uropathy, parenchymal renal pathology or impaired renal function, vicarious excretion of contrast may be a normal variant in some individuals without an underlying renal impairment and does not in itself indicate renal or hepatobiliary pathology ¹. Also, it could normally occur after injecting a high dose of contrast (e.g. triphasic CT or angiography).

It is not uncommon to see high-density pericardial fluid on a non-contrast CT chest performed in patients who underwent recent cardiac catheterisation, and it should not be mistaken for a haemopericardium ⁵.

Vicarious excretion of iodinated contrast through the kidneys may occur after oral positive contrast media studies ⁶. 

History and etymology

Vicarious in everyday English is used to refer to something taking the place of something else. It derives from the Latin word 'vicarius', itself derived from 'vicis' meaning a repeating function or role ⁷. Indeed, a vicar, in the sense of a cleric in Christianity was originally someone who was deputising for a more senior cleric ⁷.