DVT ultrasound

Background
  • Bedside ultrasound can be used to conduct compression testing on lower extremity vasculature to assess for DVT
  • Intended to be rapid, limited, but revealing most clinically significant DVTs
  • Amongst ED providers, there is a sensitivity of 95% and specificity of 96%[1]

Indications
  • Clinical suspicion of DVT: edema, tenderness over the calf, Homan's sign
  • Clinical suspicion of PE: chest pain, shortness of breath, tachycardia, tachypnea

Technique

Sites of Compression for 3-Point Evaluation

  1. Common Femoral Vein
  2. Saphenofemoral Junction
  3. Popliteal Vein

Steps
  1. Select transducer
    • Linear array vascular probe 6–10 MHz
    • For morbidly obese patients, consider abdominal probe
  2. Common Femoral Vein and Saphenofemoral Junction
    • Patient positioning
      • Reverse Trendelenburg or semi-sitting with 30 degrees of hip flexion
      • Mild external rotation (30 degrees) hip
    • Probe at medial inguinal crease
    • Apply generous compression every centimeter
    • Continue distal to 1-2cm beyond bifurcation of the common femoral vein
  3. Popliteal vein
    • Patient positioning
      • Prone, decubitus position, or seated on edge of gurney
      • Knee flexed 10–30 degree
      • Reverse Trendelenburg
    • Start with light pressure to better visualize vessels
    • Apply generous compression over the popliteal vessels to test compressibility
    • Vein usually superficial to the artery (artery is anterior)

Findings
  • Each segment of vein identified must be assess as compressible and noncompressible
    • Touching of the anterior and posterior walls indicates a normal exam
    • No touching with pressures sufficient to deform the artery indicates DVT

Images

Normal

Abnormal

Pearls and Pitfalls
  • Arteries are the thick walled and more circular vessels identified
  • Doppler flow can be used to identify different directions of flow in vessels and to identify no vascular structures
  • Noncompressible vein may be mistaken for an artery, leading to a false negative result
  • An artery may be mistaken for a non-compressible vein, leading to a false positive result
  • Lymph nodes may be confused with noncompressible vein and if found, can be identified by moving up or down 1 cm
  • Does not rule out calf DVTs
  • For a more thorough exam, scan from the saphenofemoral junction down through the adductor canal in addition to the areas described above
  • Use a curvilinear probe for obese or edematous patients
  • An appropriate amount of pressure gives complete collapse of the vein as well as some (but not full) compression of the adjacent artery.[3]

Documentation

Normal Exam

A bedside ultrasound was conducted to assess for DVT with clinical indications of edema and pain. The extremity was assessed at 3 locations – common femoral vein, saphenofemoral junction, and the popliteal vein. Sequential compressions at these sites showed fully compressible veins. No sonographic evidence of DVT at these sites.

Abnormal Exam

A bedside ultrasound was conducted to assess for DVT with clinical indications of edema and pain. The extremity was assessed at 3 locations – common femoral vein, saphenofemoral junction, and the popliteal vein. Sequential compressions at these sites showed a noncompressible popliteal vein. DVT is present at the level of the popliteal vein.

Clips

Normal Study - No DVT

Abnormal Study - Incompressible left Common Femoral Vein

See Also

References
  1. Burnside P, Brown M, and Kline J. Systematic review of emergency physician-performed ultrasonography for lower-extremity deep vein thrombosis. Acad Emerg Med. 2008; 15:493–498.
  2. http://www.thepocusatlas.com/soft-tissue-vascular/
  3. Kline JA et al. Annals of Emerg Med, 2008. PMID: 18562044
  4. http://www.thepocusatlas.com/soft-tissue-vascular/
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