Occlusion should always be confirmed with which method?

• A. Color Doppler
• B. Pulse Doppler
• C. M-mode
• D. CT angiography

Answer: (B)

When assessing a suspected occlusion, you need to verify the actual presence or absence of blood flow at the site. Pulse Doppler provides a spectral waveform that shows flow velocity and direction, making it the most definitive way to confirm occlusion. If the distal segment truly lacks flow, there will be no Doppler signal on spectral analysis, whereas any residual or collateral flow will produce a detectable waveform with characteristic velocity patterns. Color Doppler can quickly show flow, but it can miss very slow or tangential flow and is more qualitative, so it’s not as reliable for definitive occlusion confirmation. M-mode is not used for vascular flow assessment, and CT angiography, while excellent for anatomy, doesn’t provide real-time functional flow information and involves contrast and radiation.