From the Guidelines
To exclude deep vein thrombosis (DVT), a combination of clinical assessment, D-dimer testing, and imaging studies is recommended, with the most recent guidelines from 2024 suggesting that a negative D-dimer test (typically <500 ng/mL) effectively rules out DVT without further testing in patients with low clinical probability 1.
Clinical Assessment
Start with a validated clinical prediction tool like the Wells score or modified Wells score to stratify the patient's risk. Clinical assessment should include evaluation of risk factors such as immobility, recent surgery, cancer, hormonal therapy, and personal or family history of venous thromboembolism.
D-dimer Testing
For patients with low clinical probability, a negative D-dimer test (typically <500 ng/mL) effectively rules out DVT without further testing. However, D-dimer levels can be elevated in many conditions including pregnancy, inflammation, cancer, and recent surgery, reducing its specificity.
Imaging Studies
For patients with moderate to high probability or a positive D-dimer, compression ultrasonography of the lower extremities is the preferred imaging method, with sensitivity and specificity exceeding 95% for proximal DVT, as reported in a study from 2008 1. If ultrasound is negative but clinical suspicion remains high, consider repeat ultrasound in 5-7 days or alternative imaging such as venography or MR venography.
Additional Considerations
The diagnostic yield of D-dimer relies on its specificity, which varies according to patient characteristics, and the number of patients with suspected PE in whom D-dimer must be measured to exclude one PE varies between 3 in the emergency department and 10 or above in specific situations, as noted in a study from 2008 1. Compression ultrasonography and computed tomographic venography are also useful in diagnosing DVT, with the former being the preferred imaging method for the initial diagnosis of DVT, as stated in a guideline from 2024 1.
Recommendations
- Use a combination of clinical assessment, D-dimer testing, and imaging studies to exclude DVT.
- Start with a validated clinical prediction tool to stratify the patient's risk.
- Use a negative D-dimer test to rule out DVT in patients with low clinical probability.
- Use compression ultrasonography as the preferred imaging method for patients with moderate to high probability or a positive D-dimer.
- Consider repeat ultrasound or alternative imaging if clinical suspicion remains high after a negative ultrasound.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Excluding Deep Vein Thrombosis (DVT)
To exclude DVT, several methods can be employed, including:
- Clinical assessment and D-dimer testing 2, 3, 4
- Compression ultrasonography (CUS) 3, 5, 6
- Evaluation of pre-test probability using clinical decision rules 2, 3, 5, 4, 6
Clinical Decision Rules
Clinical decision rules, such as the Wells score, can be used to stratify patients into "unlikely" or "likely" categories for DVT 5, 6.
- If DVT is "unlikely", a D-dimer test can be used to exclude DVT 5, 4
- If the D-dimer level is normal, DVT can be excluded 5, 4
- If the D-dimer level is increased, CUS can be used to confirm or exclude DVT 3, 5, 6
D-Dimer Testing
D-dimer testing can be used in combination with clinical assessment and CUS to exclude DVT 2, 3, 4.
- A negative D-dimer test result can be used to exclude DVT in patients with a low pre-test probability 3, 4
- A positive D-dimer test result requires further evaluation with CUS 3, 5, 6