Which imaging modality is commonly used for routine bypass graft patency surveillance?

• A. CT angiography
• B. MRI angiography
• C. Duplex ultrasound
• D. Plain radiography

Answer: (C)

Duplex ultrasound provides a noninvasive way to monitor bypass graft patency by combining gray-scale visualization of the graft with Doppler flow assessment. This lets clinicians see the graft and anastomoses while also measuring blood flow velocities and patterns in real time. If there is a narrowing, the velocity rises at the stenosis and the waveform becomes more turbulent; absence of flow indicates occlusion. Because it’s quick, can be done at the bedside, doesn’t require contrast or radiation, and is cost-effective for routine serial checks, it’s the go-to method for regular surveillance. Other imaging modalities offer detailed anatomy but aren’t as convenient for routine follow-up: CT angiography uses radiation and iodinated contrast, MRI angiography can be costly and not always accessible or suitable for all patients, and plain radiography cannot visualize vessels effectively.