Thrombus in the renal veins. A rare cause of renal injury. Most often this develops insidiously with pulmonary embolism being the most common presenting feature. It can also present with decreased renal function, hematuria, proteinuria, and flank pain.

Renal vein thrombosis has many causes, including nephrotic syndrome, hypercoagulable disorders, malignancy, compression from a retroperitoneal mass, trauma, or complication of a renal transplant. In children, it is often secondary to dehydration or sepsis.

Renal vein thrombosis can be unilateral or bilateral. If unilateral, thrombosis more commonly occurs on the left side. Renal vein thrombosis is typically treated with anticoagulation.