Severe turbulence post-stenosis can show a reverse flow component below the systolic peak. True or false?

• A. True
• B. False
• C. Only with certain waveforms
• D. Not observed in duplex exam

Answer: (A)

Severe turbulence downstream of a stenosis can produce a brief retrograde (negative) velocity within the systolic window because of energy loss and wave reflections in the disturbed jet. When the flow accelerates through a tight stenosis, it creates a high-energy jet and a highly disturbed downstream flow with eddies and rapid pressure changes. The impedance mismatch between the narrowed segment and the distal vascular bed can generate reflected waves that briefly reverse flow even before the end of systole. In a Doppler spectrum obtained downstream of the stenosis, this can show up as a small reverse flow component just after the systolic peak. This finding supports the presence of significant stenosis and turbulent post-stenotic flow. It’s not universal, but it is a recognized possible pattern in severe disease, and you’d correlate it with other signs such as spectral broadening and high-velocity jet features.