Nature of flow: Identifies whether flow is arterial or venous. Doppler signals from both arteries and veins will reflect the hemodynamics of blood flow in normal and pathologic blood flow states.

Presence of flow: Doppler can easily determine when blood flow is present. It can become difficult to always identify when flow is absent. Optimization techniques for increasing Doppler sensitivity will be discussed in another module.

Direction of flow: Detection of direction is best done at angles approaching 0° and 180°. Flow is positive if the flow is toward the transducer and negative if flow is away from the transducer.