What type of ultrasound, venous (deep vein) or soft tissue, is needed for a patient presenting with one foot swollen and bruising?

Venous Ultrasound for Swollen and Bruised Foot

For a patient presenting with one foot swollen and bruising, a complete duplex ultrasound (CDUS) is the preferred venous ultrasound test, as it provides comprehensive evaluation from the inguinal ligament to the ankle with Doppler assessment. 1, 2

Rationale for Complete Duplex Ultrasound

• CDUS includes compression of deep veins from inguinal ligament to ankle, right and left common femoral vein spectral Doppler waveforms, popliteal spectral Doppler, and color Doppler imaging 1, 2
• Compression is performed at 2-cm intervals throughout the examination to assess for venous thrombosis 1
• CDUS evaluates both proximal and distal (calf) veins, providing complete assessment of the venous system 1
• Symptomatic areas should be specifically evaluated to determine if there is superficial venous thrombosis or other pathology, particularly if deep veins appear normal 1

Why Not Limited Protocols

• Limited protocols examining only thigh to knee require a second study in 5-7 days to safely exclude DVT, as they miss potential calf vein thrombosis 1, 2
• Limited examinations can lead to underdiagnosis and potentially medical errors 1
• Isolated distal (calf) DVT may be missed with limited protocols, yet can cause significant symptoms 1

Clinical Assessment Considerations

• Clinical prediction rules (like Wells score) can help determine pretest probability of DVT 1
• Symptoms of swelling and bruising in one foot could indicate DVT but could also represent other conditions like:
  • Soft tissue injury 3
  • Baker's cyst 3
  • Superficial thrombophlebitis 3

Special Considerations

• If symptoms persist or worsen after a negative CDUS, follow-up imaging at 5 days to 1 week is recommended 1
• For patients with whole-leg swelling and normal compression ultrasound, imaging of iliac and pelvic veins may be warranted to exclude iliocaval disease 1, 2
• If technical limitations prevent adequate assessment (excessive subcutaneous tissue, casting, etc.), alternative imaging such as CT venography or MR venography should be considered 1

Common Pitfalls to Avoid

• Relying on limited protocols that examine only proximal veins can miss calf DVT 2
• Failing to evaluate symptomatic areas when deep veins appear normal 1
• Not considering alternative diagnoses when ultrasound is negative 1
• Overlooking the need for pelvic vein imaging in patients with extensive leg swelling and normal lower extremity ultrasound 1

The Society of Radiologists in Ultrasound consensus conference strongly recommends CDUS as the standard approach for suspected DVT, as it provides the most comprehensive assessment and eliminates the need for follow-up studies in most cases 1.