Renal artery occlusion
This occurs from thrombosis in situ usually in a severely damaged arteriosclerotic vessel or more commonly from embolization. Both result in renal infarction resulting in a wide spectrum of clinical manifestations depending on the size of the artery involved. Occlusion of a small branch artery may produce no effect but occlusion of larger vessels results in dull flank pain and varying degrees of renal failure.
Embolization may occur from the heart, e.g. in atrial fibrillation. It can also occur from the aorta and renal artery where showers of cholesterol-rich atheromatous material from ulcerated arteriosclerotic plaques lodge in the small renal vessels. This leads to renal insufficiency usually with hypertension. Occasionally acute renal failure occurs, sometimes complicating catheterization of the abdominal aorta. Anticoagulants and thrombolytic agents may also precipitate cholesterol embolism.
Renal vein thrombosis
This is usually of insidious onset occurring in the nephrotic syndrome, with a renal cell carcinoma and in conditions with increased thrombosis, e.g. antithrombin III deficiency or with anticardiolipin antibodies.