Use of the radionuclide washout test in evaluation of suspected upper urinary tract obstruction.

The use of the computerized quantitative renal scan associated with the standard renogram obtained during furosemide-induced diuresis provides useful information in the assessment of suspected upper tract obstruction. With the use of 99mtechnetium diethylenetriaminepentaacetic acid or 131iodine hippuran quantitative renal scans were obtained and renograms were generated before and after intravenous furosemide injection. Rapidity of diuretic-induced radionuclide washout, as well as determination of glomerular filtration rate or effective renal plasma flow on the affected side, provides objective information with regard to renal parenchymal loss as well as upper tract emptying. We herein report our experience with 19 such patients. The radionuclide washout test is obtained easily, informative and may replace more invasive diagnostic measures.