Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer) — free guideline decision tool
This tool applies the two-level Wells score and D-dimer to direct the next diagnostic step for suspected lower-extremity DVT.
Open guideline tool →Guideline-based
Implements the decision logic from published clinical guidelines.
Runs in your browser
No installation. Enter the patient's values and get a guideline recommendation instantly.
Data stays local
Nothing is uploaded. Results are for licensed clinicians only.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Wells clinical probability | DVT unlikely (Wells ≤ 1) |
|---|---|
| D-dimer (when unlikely) | Not tested/not applicable |
→Next stepTest D-dimer first
- Pathway：DVT unlikely (Wells ≤ 1): test high-sensitivity D-dimer first (age-adjusted threshold usable). Negative excludes, positive prompts compression ultrasound
- D-dimer：High-sensitivity D-dimer < 500 ng/mL (or age-adjusted threshold) with low/intermediate probability can exclude; cannot be used for exclusion at high probability
- Ultrasound：Proximal compression ultrasound has high sensitivity/specificity; a proximal-only negative needs a 1-week repeat to catch distal-to-proximal extension, or a one-time whole-leg ultrasound
| Wells clinical probability | DVT likely (Wells ≥ 2) |
|---|---|
| D-dimer (when unlikely) | Positive |
→Next stepCompression ultrasound (CUS) directly
- Pathway：DVT likely (Wells ≥ 2): proceed directly to compression/whole-leg ultrasound, not relying on D-dimer (D-dimer cannot exclude DVT at high probability)
- Result handling：Ultrasound positive → diagnose DVT and anticoagulate; negative proximal-only CUS → add D-dimer or whole-leg ultrasound, or repeat in 1 week to exclude distal extension; negative whole-leg ultrasound → excluded
- Special：In cancer patients D-dimer has poor specificity, so proceed directly to ultrasound
Common questions
What is Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer)?
This tool applies the two-level Wells score and D-dimer to direct the next diagnostic step for suspected lower-extremity DVT.
How is Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer) calculated? What is the core formula?
Wells ≤ 1 (unlikely): D-dimer; negative excludes, positive → CUS. Wells ≥ 2 (likely): CUS directly. Proximal-only negative CUS → 1-week repeat or whole-leg ultrasound. Cancer → ultrasound directly.
When is Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer) used?
Use to decide between D-dimer, compression ultrasound, and exclusion, recognizing that a 'likely' Wells goes straight to ultrasound.
What are the key clinical points for Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer)?
D-dimer can only exclude DVT when clinical probability is low or intermediate; at high probability ultrasound is mandatory. (original synthesis · not guideline verbatim) A negative proximal-only ultrasound needs a 1-week repeat to catch distal-to-proximal extension. Cancer patients bypass D-dimer because of its poor specificity.
What are the limits and cautions when using Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer)?
For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
How is Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer) calculated in practice? Can you show a worked example?
Inputs: Wells clinical probability DVT unlikely (Wells ≤ 1), D-dimer (when unlikely) Not tested/not applicable → Result: Next step Test D-dimer first（Pathway: DVT unlikely (Wells ≤ 1): test high-sensitivity D-dimer first (age-adjusted threshold usable). Negative excludes, positive prompts compression ultrasound, D-dimer: High-sensitivity D-dimer < 500 ng/mL (or age-adjusted threshold) with low/intermediate probability can exclude; cannot be used for exclusion at high probability, Ultrasound: Proximal compression ultrasound has high sensitivity/specificity; a proximal-only negative needs a 1-week repeat to catch distal-to-proximal extension, or a one-time whole-leg ultrasound） Inputs: Wells clinical probability DVT likely (Wells ≥ 2), D-dimer (when unlikely) Positive → Result: Next step Compression ultrasound (CUS) directly（Pathway: DVT likely (Wells ≥ 2): proceed directly to compression/whole-leg ultrasound, not relying on D-dimer (D-dimer cannot exclude DVT at high probability), Result handling: Ultrasound positive → diagnose DVT and anticoagulate; negative proximal-only CUS → add D-dimer or whole-leg ultrasound, or repeat in 1 week to exclude distal extension; negative whole-leg ultrasound → excluded, Special: In cancer patients D-dimer has poor specificity, so proceed directly to ultrasound）
Run Lower-Extremity DVT Diagnostic Pathway (Wells + D-dimer) now
This tool applies the two-level Wells score and D-dimer to direct the next diagnostic step for suspected lower-extremity DVT.
Open guideline tool →For licensed clinicians. Not a substitute for clinical judgement.
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