Ultrasound diagnostics of a spontaneous arteriovenous fistula of the head and neck.

An arteriovenous fistula is an abnormal connection between the arterial and venous systems. In the literature, there are well-described ultrasound findings of iatrogenic arteriovenous fistula as a potential complication from percutaneous transarterial or transvenous procedures. The most important sign is direct visualization of the fistula in the place of the access site.