What is the first test advised for a patient presenting with an ulcer on the right lower extremity with skin breakdown but no discoloration?

First Test for Lower Extremity Ulcer

The first test advised is measurement of ankle-brachial index (ABI) using Doppler ultrasound, along with assessment of ankle systolic pressure and pedal Doppler arterial waveforms to evaluate for peripheral artery disease (PAD). 1

Rationale for ABI as Initial Test

The absence of skin discoloration in your patient makes arterial insufficiency a critical consideration that must be ruled out immediately, as this directly impacts healing potential and mortality risk. 1

Why Vascular Assessment Takes Priority

• Any lower extremity ulcer requires immediate PAD evaluation because up to 50% of leg ulcers have arterial involvement, and these patients face significantly increased risk for non-healing and limb loss. 1

• The IWGDF (International Working Group on the Diabetic Foot) provides strong recommendations that all patients with foot ulcers should have ankle or pedal Doppler arterial waveforms measured, along with both ankle systolic pressure and ABI as part of the initial evaluation. 1

• ABI measurement with <0.9 considered abnormal is useful for PAD detection, while ABI 0.9-1.3, toe brachial index ≥0.75, or triphasic pedal Doppler waveforms largely exclude PAD. 1

Clinical Algorithm for Testing

Step 1: Bedside vascular assessment 1

• Palpate foot pulses (though note that palpable pulses may still be present despite significant ischemia) 1
• Measure ABI using handheld Doppler
• Assess pedal Doppler arterial waveforms
• Measure ankle systolic pressure

Step 2: Interpret results to guide urgency 1

• If toe pressure <30 mmHg or TcPO2 <25 mmHg: consider urgent vascular imaging and revascularization
• If ankle pressure <50 mmHg or ABI <0.5: consider urgent vascular imaging and revascularization
• Normal values (ABI 0.9-1.3): PAD largely excluded, proceed with other etiologic workup

Step 3: Additional testing based on ABI results 2, 3

• If PAD excluded: evaluate for venous insufficiency, neuropathy, or other causes
• If PAD confirmed: proceed to vascular imaging (duplex ultrasound, CTA, MRA) 1

Critical Pitfalls to Avoid

• Do not rely on pulse palpation alone - even skilled examiners can miss significant ischemia when pulses are palpable. 1

• Beware of falsely elevated ABI (≥1.3) due to medial arterial calcification (Mönckeberg sclerosis), particularly in diabetic or elderly patients. In these cases, toe pressures or pedal waveform analysis become essential. 1

• Do not delay vascular assessment - patients with PAD and ulcers are at particularly high risk for major limb amputation and require emergency treatment if infection is also present. 1

Why Not Other Tests First?

While venous ulcers are statistically most common (accounting for over two-thirds of leg ulcers), 2 the absence of discoloration in your patient makes venous etiology less likely (venous ulcers typically present with hemosiderin staining, lipodermatosclerosis, and venous dermatitis). 4

Arterial disease must be excluded first because:

• It carries higher mortality and morbidity risk 1
• It fundamentally changes treatment approach (compression therapy, the mainstay of venous ulcer treatment, is contraindicated in significant arterial disease) 4
• Delayed diagnosis leads to limb loss 1