Final answer:
A biphasic waveform in Doppler tracing is typically associated with severe arterial stenosis, which leads to an altered flow that presents a reversed component after the systolic peak on the Doppler ultrasound.
Step-by-step explanation:
A biphasic waveform in Doppler tracing can result from several vascular conditions. Among the options provided, a) Severe arterial stenosis is associated with the presence of a biphasic waveform. This occurs because the stenosis, or narrowing of an artery, can alter the normal flow of blood, leading to a change in the waveform seen on Doppler ultrasound. Severe stenosis can cause a decrease in the amplitude of the forward flow component, as well as a noticeable reversed flow component after the systolic peak, which is characteristic of a biphasic waveform. On the other hand, b) Normal blood flow typically produces a triphasic waveform in arterial Doppler studies, not biphasic. c) Venous insufficiency and d) Lymphatic blockage are not typically associated with arterial Doppler waveforms, as they affect different components of the circulatory system.