Clinical technique for identification of external carotid bruits

A 66-year-old woman had an asymptomatic bruit over the right carotid bifurcation. Carotid Doppler and real-time ultrasound studies demonstrated an isolated 50 to 75% stenosis of the right external carotid artery. We devised a simple maneuver to determine which artery, internal or external carotid, caused the bruit.