Vicarious contrast material excretion in patients with acute unilateral ureteral obstruction.

Radiographs of 45 patients with evidence of acute unilateral ureteral obstruction at intravenous urography, obtained at least 24 hours after injection of contrast material, were retrospectively studied. Vicarious contrast material excretion (VCME) as evidence by gallbladder opacification on delayed radiographs was seen in 19 patients (42%), 10 of whom also showed extravasation of contrast material. A total of 15 of the 45 patients developed spontaneous extravasation; 10 (67%) showed VCME, while only nine of the 30 patients (30%) who did not have spontaneous extravasation of contrast material showed VCME. The creatinine level was elevated (greater than 1.5 mg/dL [133 mumol/L]) in four patients with VCME and in six patients without. This series indicates that VCME is more common than previously appreciated in patients with acute unilateral ureteral obstruction and occurs with greater frequency when obstruction is associated with contrast material extravasation.