What indicates laminar flow on spectral Doppler?

• A. Absence Of A Spectral Window
• B. Turbulent Flow
• C. No Doppler Signal
• D. Presence Of Spectral Window

Answer: (D)

Laminar flow shows a narrow, orderly Doppler spectrum with a clear gap in the display—the spectral window. When the flow is uniform across the Vessel, velocities cluster in a small range, producing a sharp, compact spectral envelope and a region within the trace that is free of signal. If the flow becomes turbulent, a wide range of velocities fills that area, leading to spectral broadening and no visible window. So the presence of a spectral window indicates laminar flow. Absence of a window would suggest turbulence; no Doppler signal would mean little or no flow.