# Wells Score Calculator for DVT

Calculate the Wells Score for DVT (deep vein thrombosis) risk assessment. Enter clinical criteria to determine probability and recommended diagnostic pathway.

## What this calculates

Assess the clinical probability of deep vein thrombosis (DVT) using the Wells Score. This validated scoring system uses 10 clinical criteria to classify patients into low, moderate, or high probability categories and guide the diagnostic workup.

## Inputs

- **Active cancer (treatment within 6 months or palliative)** — +1 point
- **Paralysis, paresis, or recent leg cast/immobilization** — +1 point
- **Bedridden >3 days or major surgery within 12 weeks** — +1 point
- **Localized tenderness along deep venous system** — +1 point
- **Entire leg swollen** — +1 point
- **Calf swelling >3 cm compared to other leg** — +1 point. Measure 10 cm below tibial tuberosity.
- **Pitting edema (greater in symptomatic leg)** — +1 point
- **Collateral superficial veins (non-varicose)** — +1 point
- **Previously documented DVT** — +1 point
- **Alternative diagnosis at least as likely as DVT** — -2 points

## Outputs

- **Wells Score** — Total Wells Score for DVT (-2 to 9)
- **Risk Category (3-tier)** — formatted as text — Low, moderate, or high probability using the original 3-tier model
- **Risk Category (2-tier)** — formatted as text — DVT likely or unlikely using the modified 2-tier model
- **Approximate DVT Prevalence** — formatted as text — Estimated probability of DVT in this risk group
- **Suggested Next Step** — formatted as text — Clinical pathway suggestion based on score

## Details

The Wells Score for DVT was developed by Dr. Philip Wells and colleagues in 1997 and has become the standard clinical prediction tool for assessing DVT probability before ordering diagnostic tests. It helps clinicians decide whether to start with a D-dimer blood test or proceed directly to ultrasound imaging.

**Scoring criteria (each +1 point unless noted):**
- Active cancer (treatment within 6 months or palliative)
- Paralysis, paresis, or recent plaster immobilization of the leg
- Bedridden for >3 days or major surgery within 12 weeks
- Localized tenderness along the deep venous system
- Entire leg swollen
- Calf swelling >3 cm larger than the asymptomatic side (measured 10 cm below the tibial tuberosity)
- Pitting edema confined to the symptomatic leg
- Collateral superficial veins (non-varicose)
- Previously documented DVT (+1)
- Alternative diagnosis at least as likely as DVT (-2 points)

**3-tier interpretation:**
- Score 0 or less: Low probability (~5% have DVT)
- Score 1-2: Moderate probability (~17% have DVT)
- Score 3+: High probability (~53% have DVT)

**2-tier (modified) interpretation:**
- Score 1 or less: DVT unlikely -- proceed with D-dimer
- Score 2+: DVT likely -- proceed with ultrasound

The 2-tier model is now more widely used in clinical practice because it creates a cleaner decision pathway: "unlikely" patients get a D-dimer first (if negative, DVT is ruled out), while "likely" patients go straight to imaging.

This tool is for educational purposes only and should not replace professional medical advice.

## Frequently Asked Questions

**Q: What is DVT and why is risk assessment important?**

A: Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the leg. It is dangerous because the clot can break loose and travel to the lungs, causing a pulmonary embolism (PE), which can be fatal. Risk assessment matters because not every patient with leg swelling or pain has DVT. The Wells Score helps determine who needs urgent imaging versus who can be safely evaluated with a simple blood test first.

**Q: What is a D-dimer test and when is it useful?**

A: D-dimer is a blood test that measures a protein fragment produced when blood clots dissolve. A negative D-dimer (below 500 ng/mL) has a very high negative predictive value, meaning it reliably rules out DVT in low-to-moderate risk patients. However, D-dimer can be elevated for many reasons (infection, inflammation, pregnancy, recent surgery, cancer), so a positive result does not confirm DVT. That is why D-dimer is most useful in Wells Score "unlikely" patients where a negative result avoids the need for ultrasound.

**Q: What does the -2 points for alternative diagnosis mean?**

A: The 'alternative diagnosis at least as likely as DVT' criterion (-2 points) reflects the clinical judgment that another condition (like a Baker's cyst, cellulitis, muscle strain, or post-surgical swelling) could explain the symptoms equally well. It is subjective and relies on the clinician's assessment. This is the most significant criterion in the scoring because it can move a patient from 'likely' to 'unlikely' for DVT, changing the entire diagnostic approach.

**Q: Can the Wells Score be used for pulmonary embolism?**

A: There is a separate Wells Score specifically for pulmonary embolism (PE) that uses different criteria, including heart rate >100, signs of DVT, previous PE/DVT, hemoptysis, malignancy, immobilization, and the clinical judgment criterion. The DVT and PE versions are distinct tools and should not be confused. This calculator is specifically for DVT assessment.

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Source: https://vastcalc.com/calculators/health/wells-score-dvt
Category: Health & Fitness
Last updated: 2026-04-08