A 70-year-old male presents to the emergency room complaining of weakness, dizziness and back pain. He denies nausea, vomiting, diarrhea, chest pain, palpitations, shortness of breath, urinary symptoms, or black stools. His past medical history is significant for diabetes mellitus, diabetic nephropathy and retinopathy, hypertension, atrial fibrillation and chronic leg cellulitis. He takes warfarin for chronic anticoagulation. On physical examination, his blood pressure is 120/70 mmHg and his heart rate is 110 and irregular. His WBC count is 10,500/mm³, hemoglobin level is 7.0 g/dL and platelet count is 170,000/mm3. An abdominal CT image is shown on the slide below. Which of the following is the most likely diagnosis?

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11ec25c8_d83f_0c3d_bc81_2b8ea8538baa_MD0003_00 This patient's history of anticoagulation, symptoms of weakness and dizziness, and evidence of anemia and tachycardia should immediately raise concern for internal hemorrhage. The risk of bleeding while on warfarin therapy is greatest in patients with risk factors such as diabetes, age > 60, hypertension and alcoholism. A supratherapeutic INR also increases one's risk of hemorrhage, although in the case of retroperitoneal hematomas, even therapeutic-range INRs confer significant risk. This patient's back pain should put retroperitoneal hematoma high on the differential, and warrants an abdominal CT. The above CT image reveals a large isodense collection in the right retroperitoneum, which lies anterior to the psoas muscle and displaces the right kidney anteriorly. The CT findings are consistent with a spontaneous retroperitoneal hematoma (Choice C). (Choice A) The classic triad of renal cell carcinoma (RCC) is hematuria, abdominal mass and flank pain. On abdominal CT, RCC presents as a lesion within the kidney parenchyma that enhances with contrast administration. The above lesion is extrinsic to the kidney. (Choice B) A vertebral fracture could certainly cause back pain, and may occur in osteoporotic patients in the absence of trauma. However, the above CT image does not depict a vertebral abnormality. (Choice D) Hydronephrosis is a condition in which the renal pelvis dilates due to distal obstruction of the genitourinary system. Patients present with flank pain. CT scan in hydronephrosis demonstrates dilation of the renal pelvis, and may help in identifying the source of obstruction (e.g. kidney stones). (Choice E) Mesenteric ischemia presents with abdominal pain out of proportion to physical exam findings. It is most common in elderly patients, and may result from a cardiac embolus (as in atrial fibrillation), arterial thrombosis (as in atherosclerosis), or other etiology (as in shock or vasoconstriction). CT findings include bowel wall thickening, pneumatosis intestinalis, and mesenteric thrombi. Educational objective: Anticoagulation with warfarin places patients at risk for hemorrhage. Retroperitoneal hematoma may occur even without a supratherapeutic INR. Back pain and signs and symptoms of hemodynamic compromise should raise suspicion for retroperitoneal hematoma.

A 70-Year-Old Male Presents to the Emergency Room Complaining of Weakness