Warfarin-induced bilateral renal hematoma causing acute renal failure

Acute renal failure due to bilateral hematoma is a rare complication of anticoagulant warfarin therapy. A 43-year-old man presented with complaints of hematuria and abdominal pain. He had been receiving warfarin for six years, after placement of an aortic valve prosthesis. One week prior to admission, he sustained a urinary tract infection which was treated with third-generation cephalosporin and indomethacin. His serum creatinine level was 1.8 mg/dl with an INR of 15. Three days later, he developed anuria and was treated with hemodialysis. Renal ultrasonography disclosed moderate bilateral hydronephrosis. Computed tomography without contrast enhancement showed bilateral extensive hyperdense thickening of the renal and ureteral walls and high-attenuation areas. Conservative treatment was preferred and diuresis resumed spontaneously, lumbar pain disappeared, and serum creatinine level returned to normal. One month later, renal computed tomography was found normal.