Arteriovenous malformation incidentally found by ultrasonography in a thigh hematoma after contusion

Vascular malformations in extremities are difficult to detect in cases of minor trauma. The authors report a case of an arteriovenous malformation (AVM) incidentally found by ultrasonography in a contusion. After a slip down, a 52-year-old man who had undergone total arthroplasty in both hips 10 years earlier complained of an ovoid right hip swelling that had gradually increased in size. Suspecting a simple cyst or hematoma, the swelling was examined by ultrasonography, which revealed a subcutaneous hematoma with arterial flow connected to muscle. Arteriography revealed an AVM around the right hip joint. Due to the presence of multiple arteriovenous shunts, a conservative treatment course was adopted and after 3 weeks of treatment the swelling almost completely resolved. It appears that the small AVM may have existed congenitally before hip surgery and the contusion over the AVM had led to hematoma rather than an arteriovenous fistula. The authors emphasize the usefulness of ultrasonography for the diagnosis of posttraumatic swelling.