A 68 year-old retired truck driver comes to your office for evaluation of swelling in his legs. The patient is a smoker and has been taking medications to control hypertension for the past 25 years. You are concerned about the risk for peripheral vascular disease. Which test is most appropriate to order initially to evaluate for this condition?

Peripheral vascular disease (most commonly peripheral arterial disease) results from progressive atherosclerotic narrowing of peripheral arteries, leading to reduced blood flow to the lower extremities. Risk factors include long-standing hypertension, smoking, and advanced age. Initial evaluation focuses on noninvasive, cost-effective tests that assess arterial perfusion. The ankle-brachial index is the standard first-line screening tool for suspected lower extremity arterial disease. Rationale: A. Venogram is used primarily to evaluate venous disorders such as deep vein thrombosis or venous insufficiency, not arterial disease. It involves contrast imaging of the venous system and is more invasive than initial screening tests. Since peripheral vascular disease is suspected, venous imaging is not the most appropriate first step. B. CT scan of the lower legs may provide detailed vascular imaging, but it is not typically used as an initial screening tool for peripheral arterial disease. It is more expensive, involves radiation exposure, and is usually reserved for preoperative planning or complex cases requiring detailed anatomical evaluation after initial screening. C. Ankle-Brachial Index (ABI) is the most appropriate initial test because it is a simple, noninvasive comparison of systolic blood pressure in the ankle and brachial arteries. A reduced ABI indicates decreased arterial perfusion consistent with peripheral arterial disease. It is widely recommended as the first-line diagnostic screening tool in patients with risk factors such as smoking and long-standing hypertension. D. PET scan is not used in the evaluation of peripheral vascular disease. It is primarily utilized in oncology and certain neurological or cardiac metabolic assessments. It does not provide practical or relevant information regarding arterial blood flow in the lower extremities and is therefore inappropriate for this clinical scenario.