Retroperitoneal hematoma compressing a single functioning kidney: an unusual cause of obstructive renal failure.

We report a case of a retroperitoneal hematoma occurring in a patient under anticoagulation therapy for deep-venous thrombosis and presenting as an anuric acute renal failure. A coexisting polycythemia vera led to misdiagnosis that could have been life-threatening. A woman, known for polycythemia vera and a single functioning right kidney, was admitted with mild abdominal pain in a context of recent deep venous thrombosis under low-molecular weight heparin. Clinical examination revealed hepatomegaly associated with polycythemia vera. Biochemical evaluation disclosed an acute renal failure, and renal ultrasonography showed no dilation of the renal pelvis. Retroperitoneal hematoma resulted in shock, progressive anemia and obstructive renal failure, related to renal pelvic compression. A right renal indwelling catheter was introduced to restore urine flow after one hemodialysis session, and an inferior vena cava filter was placed because of anti-coagulation contra-indication. However, pulmonary embolism occurred, so that oral anticoagulants were introduced. The hematoma resorbed spontaneously, and a year after this episode, the patient is still alive and well. Retroperitoneal hematoma is a rare cause of obstructive acute renal failure and a life-threatening complication of anti-coagulation therapy.