Vesicoureteral Reflux Causing Improved Visualization on the Delayed Excretory Urogram

If contrast medium is seen in the renal pelvis and ureter (or renal segment) on delayed films but was poorly visualized or not visualized on early films, it may have been excreted by the opposite kidney and reached the affected kidney or renal segment by reflux from the bladder. This sign was observed in 13.5% of 200 patients with vesicoureteral reflux whose early and delayed films were compared. Most patients in whom this test was positive had low-pressure reflux.