In a renal transplant recipient with persistently poor graft function, the
flow phase of a renal scan incidentally revealed multiple venous collateral
s with focally increased vascular activity near the left lobe of the liver
(quadrate lobe), This was initially assumed to represent superior vena cava
(SVC) obstruction. A renal biopsy was contemplated to exclude acute reject
ion because of a nondiagnostic flow phase (loss of a bolus effect). However
, because the possibility of venous obstruction at the level of the subclav
ian and/or brachiocephalic veins (without involving the SVC) also existed,
another renal scan was performed, with injection of radiotracer into the co
ntralateral arm. This showed a patent SVC and reasonably preserved renal pe
rfusion consistent with acute tubular necrosis, Subsequently, left subclavi
an vein obstruction was identified. The graft function improved with conser
vative management for acute tubular necrosis, These findings illustrate the
danger of considering only SVC obstruction when collateral flow patterns a
nd focal hot spots in the liver are present.