Non-visualisation of kidney in excretory urogram is seen in

B i.e. Renal vein thrombosis - Nonvisualization of kidney (or absence of nephrogram) occurs in complete renal ischemia secondary to occlusion of main renal aery, (global absence) or focal renal infarction/ischemia secondary to focal aerial occlusion or renal vein thrombosisQ or space occupying lesions (segmental absence). - Persistent dense nephrogram (both increasingly or immediate) is seen in systemic hypotension, severe dehydrationQ, renal aery stenosis, renal vein thrombosis, tubular obstruction & damage and urinary tract obstruction (eg ureteral obstruction)Q but not in systemic hypeension. Although hydronephrosis usually 1/t scalloped/shell i.e. non smooth rim nephrogramQ.