Evaluation of obstructive uropathy with diuretic renography.

Diuretic renography has been recommended as a useful test to distinguish obstructed from dilated, but not obstructed, urinary systems. Twenty-four diuretic renograms were performed in 20 children, and a good correlation was found with other indicators of obstruction. The sensitivity for identifying obstruction was 83%, with a specificity of 94%. Severe hydroureteronephrosis may blunt or even mask the effect of diuresis on causing emptying of the tracer from the renal pelvis. Some kidneys did not drain well with the patient in a supine position but did empty with a change of position; these kidneys should be regarded as nonobstructed.