Computed tomography of renal pelvic filling defects.

Thirteen patients with a variety of renal pelvic filling defects were evaluated using computed tomography (CT). Nonopaque calculi and some blood clots can be more accurately differentiated with this modality than has heretofore been possible. In transitional-cell carcinoma of the renal pelvis, the main value of CT appears to be in tumor staging. CT may also be helpful where urography cannot discriminate between extrinsic compression and true intraluminal renal pelvic defects.