How do you differentiate between venous and arterial ulcers in an adult patient with a history of vascular disease?

Differentiating Venous from Arterial Ulcers

Venous ulcers are located around the medial malleolus with irregular borders and granulation tissue, while arterial ulcers occur distally on toes/feet with intense pain, well-demarcated borders, and dry appearance—but you must obtain an ankle-brachial index (ABI) in all patients because 16% have mixed disease that will be missed on clinical exam alone. 1

Location and Appearance

Venous ulcers:

• Located around the medial malleolus 1
• Irregular but well-defined borders 1
• Base of granulation tissue (moist appearance) 1, 2
• Surrounded by stasis dermatitis and brown hemosiderin pigmentation 2

Arterial ulcers:

• Located distally on toes or feet 2
• Well-demarcated borders with dry, crusted appearance 1
• Scant or absent granulation tissue 1, 2
• Associated with pale or cyanotic skin 1

Pain Characteristics

Venous ulcers:

• Generally less painful 1
• Pain improves with leg elevation 2

Arterial ulcers:

• Intense pain, especially at rest 1
• Associated with claudication and rest pain 1
• Pain worsens with leg elevation and improves with dependency 2
• Typically requires narcotic analgesia 3

Physical Examination Findings

Venous disease indicators:

• Limb edema that improves with elevation 2
• Varicose veins 4
• Telangiectasias, corona phlebectatica, atrophie blanche 4
• Lipodermatosclerosis 4

Arterial disease indicators:

• Absent or diminished pedal pulses 1
• Cool extremity 1
• Femoral bruits 1
• Slow venous filling time 1

Critical Diagnostic Testing

You cannot rely on clinical examination alone—up to 50% of patients with foot ulcers have peripheral arterial disease requiring objective vascular testing. 1

Ankle-Brachial Index (ABI) interpretation:

• ABI <0.9 indicates peripheral arterial disease 1
• ABI <0.5 or ankle pressure <50 mmHg indicates severe ischemia requiring urgent revascularization 3, 1
• ABI 0.9-1.3 largely excludes arterial disease 1
• ABI ≥1.3 suggests medial arterial calcification (common in diabetes) and requires alternative testing such as toe pressures or Doppler waveforms 1

Additional vascular testing:

• Triphasic pedal Doppler arterial waveforms exclude significant arterial disease 1
• Toe-brachial index ≥0.75 excludes arterial disease 1
• Duplex ultrasound is first-line for confirming venous disease, evaluating flow direction, reflux, and obstruction 1

Critical Pitfall: Mixed Arterial-Venous Disease

Approximately 16% of patients with venous ulcers have concomitant arterial occlusive disease. 1 Failure to identify arterial disease can lead to inappropriate compression therapy, which may cause tissue necrosis in patients with occult arterial insufficiency. 2

In diabetic patients:

• Neuropathy may mask pain symptoms 1
• Medial arterial calcification makes ABI unreliable 1
• Alternative testing (toe pressures or Doppler waveforms) should be considered 1

Treatment Implications

Venous ulcers:

• Compression therapy is the initial treatment of choice (minimum 20-30 mmHg, increasing to 30-40 mmHg in severe cases) 1
• Never apply compression if arterial disease is present 2

Arterial ulcers:

• Increasing blood supply through revascularization is the primary treatment 1
• For toe pressure <30 mmHg or ankle pressure <50 mmHg, urgent vascular imaging and revascularization should be considered 1
• Without adequate revascularization, arterial ulcers have higher risk of amputation 1

Algorithmic Approach

1. Examine location: Medial malleolus suggests venous; distal toes/feet suggests arterial 1, 2
2. Assess pain: Minimal pain with elevation relief suggests venous; severe rest pain worsening with elevation suggests arterial 1, 2
3. Check pulses: Absent pedal pulses strongly suggest arterial disease, but palpable pulses do not exclude significant ischemia 1
4. Obtain ABI on all patients: This is mandatory—clinical exam alone misses arterial disease in up to 50% of cases 1
5. If ABI ≥1.3 (noncompressible vessels): Obtain toe pressures or Doppler waveforms 1
6. If any concern for arterial disease: Do not initiate compression therapy until arterial insufficiency is excluded 2