Final answer:
A monophasic Doppler tracing in the lower extremity is considered abnormal, often indicating peripheral arterial disease (PAD) and suggesting reduced arterial blood flow, not lymphatic blockage.
Step-by-step explanation:
A monophasic Doppler tracing in the lower extremity is abnormal. In a healthy individual, the Doppler waveform of lower extremity arteries should be triphasic, with a rapid systolic peak followed by a brief reversal of flow during early diastole and a forward flow during late diastole.
A monophasic tracing indicates a loss of the normal triphasic flow pattern, which may suggest significant peripheral arterial disease (PAD) and reduced blood flow, possibly due to a blockage or narrowing of the arteries. It is not indicative of a lymphatic blockage. The monophasic flow can be caused by conditions such as atherosclerosis or other forms of arterial occlusive disease.
However, in certain clinical scenarios, such as immediately after exercise or in very small peripheral arteries, a monophasic flow pattern may be seen in normal circumstances too, hence context is important when interpreting the waveform.