Vesicoureteral reflux simulating renal function: CT appearance.

Urine may enter the pelvicalyceal system of the kidney either through renal excretion or via the ureter by vesicoureteral reflux. Opacified cyalyces and pelvis after the administration of intravenous contrast material are therefore not necessarily proof that the kidney is functioning. This phenomenon, well known from intravenous urography, may be observed on computed tomography studies as well. We present a case in which a CT scan showed a normal left and a contracted pyelonephritic right kidney with contrast material in pelvis and calydes of both kidneys without parenchymal enhancement on the right side. Subsequently marked vescioureteral reflux to the right kidney was demonstrated on cystourethrography and the kidney was shown to have no function on a nuclear scan. Contrast material in the collecting system associated with a small non-enhancing kidney on CT scan should suggest vesicoureteral reflux.