How do I order a deep vein thrombosis (DVT) ultrasound?

How to Order a DVT Ultrasound

When evaluating a patient with suspected deep vein thrombosis (DVT), order a complete duplex ultrasound (CDUS) as the preferred venous ultrasound test for diagnosis. 1

Pre-Test Assessment

• First assess the patient's pretest probability of DVT using the Wells score before ordering ultrasound 1:

  • Score ≥2 indicates DVT is likely
  • Score <2 indicates DVT is unlikely

• For patients with low (unlikely) pretest probability:

  • Order a high-sensitivity D-dimer test first 1
  • If D-dimer is negative, DVT can be safely excluded without ultrasound 1, 2
  • If D-dimer is positive, proceed with ultrasound 1, 2

• Ultrasound is appropriate for patients with:

  • Likely pretest probability of DVT (Wells score ≥2)
  • Unlikely pretest probability but positive D-dimer
  • Cases where pretest probability was not assessed 1

Ultrasound Type to Order

• Specify "Complete Duplex Ultrasound" (CDUS) on your order 1

  • This is the preferred and most comprehensive test 1
  • CDUS includes compression from inguinal ligament to ankle, including posterior tibial and peroneal veins 1
  • Includes spectral Doppler waveforms of common femoral veins (both sides) and popliteal vein (symptomatic side) 1

• Avoid ordering limited protocols that don't include calf veins, as these require a second follow-up study in 5-7 days 1

• If CDUS is not available (e.g., after hours), a point-of-care Extended Compression Ultrasound (ECUS) from thigh to knee is appropriate, but will require follow-up CDUS in 5-7 days 1

Order Details to Include

• Specify the symptomatic leg(s) 1

• Include relevant clinical information on the order:

  • Symptoms (pain, swelling, erythema) 2
  • Duration of symptoms 2
  • Risk factors from Wells score (cancer, immobilization, surgery, etc.) 1
  • D-dimer result if obtained 2, 3

• Request evaluation of symptomatic areas, even if outside standard protocol, to identify possible superficial venous thrombosis or other pathology 1

Follow-Up Ultrasound Considerations

• For untreated calf DVT: Order repeat scan in 1 week or sooner if symptoms worsen 1, 4
• For negative CDUS with persistent symptoms: Consider repeat scan in 5-7 days 1, 4
• For suspected iliocaval DVT (whole-leg swelling with normal compression ultrasound): Order additional imaging such as pelvic venous ultrasound, CT or MR venography 1, 4

Common Pitfalls to Avoid

• Ordering four-extremity duplex ultrasound is rarely necessary and inefficient 5
• Ordering ultrasound without assessing pretest probability and D-dimer in low-risk patients 1
• Failing to specify complete duplex ultrasound, which may result in limited studies requiring follow-up 1
• Not ordering follow-up imaging for untreated calf DVT, which has approximately 15% risk of extension to proximal veins 4