CT scanning in the diagnosis of pelvicalyceal filling defects.

Of 9 patients found to have a nonopaque filling defect on intravenous pyelogram, 6 were shown to have radiolucent urinary calculi, 2 had intrapelvic blood clots and 1 had a ureteral tumor. The diagnosis was made by computerized tomography and confirmed by surgery in all but the case of ureteral tumor. We recommend CT scanning as the method of choice for unexplained filling defects in the renal pelvis and ureter or when a nonopaque calculus is suspected.