Images in clinical medicine. Retroperitoneal hemorrhage.

A 54-year-old man presented with severe pain in the right side of the groin that radiated to the calf and anteromedial thigh of the right leg, causing him to lie with his hips flexed. Hip extension exacerbated the pain. Because of venous thrombosis of the legs, he had received warfarin for the previous 10 months. There was a palpable mass in the right side of the groin. Neurologic examination revealed weakness of the right quadriceps muscle and thigh adductors and a depressed knee jerk and loss of sensation on the anteromedial thigh and in the territory of the saphenous nerve on the right side. Laboratory studies showed a white-cell count of 21,400 per cubic millimeter and a hemoglobin level of 14.3 g per deciliter. The international normalized ratio was 3.4. Computed tomography of the pelvis without contrast enhancement showed extensive swelling of the right psoas muscle and iliac muscle (solid circle). The high-attenuation component in the absence of intravenous contrast enhancement is characteristic of hematoma (arrows). After the restoration of normal blood coagulation, the patient was treated conservatively. Three months later, he had only marginal paresis of the right quadriceps muscle and thigh adductors.