Radiographic manifestations of spontaneous renal sinus hemorrhage.

The radiographic and computed tomographic features of nontraumatic (spontaneous) hemorrhage into the renal sinus in four patients on anticoagulant therapy are described. Spontaneous renal sinus hemorrhage, a benign self-limited process related to anticoagulation, may have a lesser association with occult renal neoplasms than other types of renal bleeding. The diagnostic criterion of uncomplicated bleeding into the renal sinus is extrinsic compression of the pyelocaliceal system that proves to be completely reversible with spontaneous dissolution of clot. Often there is impaired excretion of contrast material with proximal caliectasis.