Difference Between Venous and Arterial Ultrasound
Venous ultrasound examines veins to detect blood clots (deep vein thrombosis), valve dysfunction, and venous insufficiency, while arterial ultrasound evaluates arteries to assess blood flow blockages, narrowing (stenosis), and atherosclerotic disease. 1, 2
What Each Test Looks For
Venous Ultrasound
- Detects blood clots (DVT) in deep veins using compression technique—the vein should collapse when pressed; if it doesn't, a clot is present 3, 2
- Evaluates venous reflux and valve incompetence that causes varicose veins and chronic venous insufficiency 1
- Assesses venous flow patterns using Doppler to detect abnormal waveforms suggesting upstream obstruction 4
- Examines superficial and deep venous systems from groin to ankle for lower extremities 5
Arterial Ultrasound
- Identifies arterial stenosis and occlusions from atherosclerotic plaque buildup 2, 6
- Measures blood flow velocity and direction to determine severity of blockages—sensitivity ~90% and specificity ~99% for detecting symptomatic stenoses 2
- Detects aneurysms, embolisms, and arterial inflammation 2
- Evaluates adequacy of blood supply to limbs in peripheral arterial disease 3, 2
How the Techniques Differ
Venous Ultrasound Technique
- Compression is the key maneuver—the ultrasound probe physically compresses the vein to check for clots 3, 2
- Spectral Doppler evaluates flow patterns that should be phasic with respiration in normal veins 5
- Color Doppler shows spontaneous venous flow and augmentation with distal limb compression 2
Arterial Ultrasound Technique
- Measures peak systolic velocities to quantify stenosis severity—higher velocities indicate tighter narrowing 2
- Assesses arterial waveform morphology—triphasic waveforms are normal, monophasic suggests downstream disease 2, 6
- Calculates ankle-brachial index (ABI) using Doppler pressures to diagnose peripheral arterial disease 3
Clinical Context: When Each Is Used
Order Venous Ultrasound When:
- Leg swelling, pain, or heaviness suggesting possible DVT 3
- Varicose veins with symptoms to map venous insufficiency before treatment 1
- Suspected pulmonary embolism to look for source DVT in legs 3
- Catheter dysfunction or arm swelling in dialysis or central line patients 4
Order Arterial Ultrasound When:
- Claudication (leg pain with walking) suggesting arterial insufficiency 3
- Non-healing wounds or tissue loss requiring arterial flow assessment 7
- Absent pulses or cool extremities indicating possible arterial occlusion 2
- Pre-operative vascular mapping for bypass surgery planning 3
Critical Distinction in Pathophysiology
Venous disease involves blood pooling and clotting due to sluggish flow, valve failure, or obstruction—the concern is clot formation and embolization to lungs 3, 1. Arterial disease involves inadequate oxygen delivery due to blockages reducing forward flow—the concern is tissue ischemia and limb loss 2, 7.
Common Pitfall to Avoid
Do not order arterial ultrasound for suspected DVT or venous insufficiency—these are fundamentally different vascular systems requiring different imaging approaches 1. The pathophysiology of varicose veins and DVT is venous reflux and thrombosis, making arterial imaging irrelevant to diagnosis 1.