The carotid bulb is the slightly dilated or widened portion at the origin of the internal carotid artery, just beyond the carotid bifurcation. This natural expansion creates an area of slower, sometimes reversed blood flow along the outer wall, which is why atherosclerotic plaque tends to accumulate preferentially at this site. On Doppler ultrasound, the carotid bulb normally shows a brief period of flow reversal during early diastole, which is a characteristic finding that helps identify this specific location. Understanding the anatomy and hemodynamics of the carotid bulb is essential for sonographers who perform carotid duplex examinations, as this is where the most clinically significant disease is often found.
Sonography Term