Carotid bulb color flow is best described as?

• A. Boundary layer separation with flow reversal and aliasing is typical
• B. No boundary layer separation and no flow reversal
• C. Flow reversal with aliasing present
• D. Boundary layer separation with flow reversal and no aliasing

Answer: (D)

The carotid bulb creates a sudden expansion, which causes the boundary layer to detach from the wall. This separation forms a recirculation zone where the flow reverses locally, especially near the outer wall. In color Doppler, that reversed flow is seen without exceeding the velocity scale, so you don’t typically see aliasing in this region. So the description that matches is boundary layer separation with flow reversal and no aliasing. The other patterns either imply no separation, no reversal, or introduce aliasing that isn’t characteristically expected in the bulb.