Duplex ultrasound of a normal superficial femoral artery typically shows:

• A. Triphasic or multiphasic with sharp systolic upstroke, brief early diastolic reversal, followed by forward flow
• B. Dampened biphasic waveform with reduced diastolic flow
• C. Monophasic waveform with reduced or absent diastolic flow
• D. Flat, nonpulsatile flow

Answer: (A)

A healthy superficial femoral artery on duplex shows a triphasic waveform (or occasionally multiphasic) with a sharp systolic upstroke, a brief early diastolic reversal, and forward flow in late diastole. This pattern reflects normal high distal resistance and arterial compliance, producing that quick systolic push followed by a small dip and then continued forward flow as the pulse propagates. When you see a dampened biphasic waveform with reduced diastolic flow, it points to some downstream disease or altered resistance rather than normal flow. A monophasic waveform with little or no diastolic flow suggests more extensive obstruction, and flat nonpulsatile flow indicates near-occlusion or occlusion. Therefore the triphasic/multiphasic description is the hallmark of a normal superficial femoral artery.