Differential Diagnosis for Lower Extremity Arterial Duplex Study

Single Most Likely Diagnosis

• Peripheral Artery Disease (PAD): The significant drop in velocity from the proximal to distal segments of the lower extremity arteries, particularly the decrease from the common femoral to the posterior and anterior tibial arteries, suggests a stenotic or occlusive process consistent with PAD. The velocities provided, especially the low velocities in the posterior tibial (16 CM/seconds) and anterior tibial (26 CM/seconds) arteries, indicate significant narrowing or blockage.

Other Likely Diagnoses

• Atherosclerosis: Given the patient's age and the pattern of arterial disease, atherosclerosis is a likely underlying cause of the observed arterial narrowing. The disease process typically affects older adults and can lead to the development of PAD.
• Thromboangiitis Obliterans (Buerger's Disease): Although less common, this condition could be considered, especially if the patient is a young smoker. It involves inflammation and thrombosis of the blood vessels and could explain the observed arterial velocities.

Do Not Miss Diagnoses

• Acute Limb Ischemia: Although the velocities do not immediately suggest an acute occlusion, any significant decrease in limb perfusion could lead to acute limb ischemia, which is a medical emergency. The low velocities in the distal arteries could indicate a chronic process, but an acute component should always be considered.
• Popliteal Artery Entrapment Syndrome: This condition involves compression of the popliteal artery due to muscular or tendinous structures and could lead to symptoms and findings similar to those of PAD. It's more common in younger patients and athletes.

Rare Diagnoses

• Fibromuscular Dysplasia: A non-atherosclerotic, non-inflammatory vascular disease that affects medium- and large-sized arteries, most commonly the renal and internal carotid arteries, but can also affect the lower extremity arteries. It would be an unusual cause of the observed findings but should be considered in younger patients without risk factors for atherosclerosis.
• Vasculitis (e.g., Giant Cell Arteritis, Takayasu Arteritis): These are inflammatory conditions that can affect the blood vessels and lead to stenosis or occlusion. They are less common and typically present with systemic symptoms, but could be considered in the differential diagnosis, especially if there are atypical features or systemic symptoms.