Wells Score Calculator (DVT/PE)

The Wells Score Calculator (DVT/PE) estimates the clinical pretest probability of a venous thromboembolism — either a deep vein thrombosis (DVT) in the leg or a pulmonary embolism (PE) in the lungs. Developed by Dr. Philip Wells and colleagues, the score adds up well-validated risk factors and clinical signs, then sorts the result into low, moderate, or high probability bands. Those bands tell clinicians whether a simple blood test (D-dimer) is enough to safely rule out a clot, or whether imaging is needed. This tool combines both the DVT and PE versions in one place, with a live running score and a clear, color-coded readout.

What is the Wells Score?

The Wells score is a clinical prediction rule (also called a clinical decision rule). Instead of relying on gut feeling, it structures the assessment of a suspected clot into a short checklist of objective items. Each item carries a point value; the sum places the patient into a risk category that has a known, studied probability of actually having the condition. This standardizes decision-making, reduces unnecessary imaging, and helps make sure low-risk patients are not over-tested while high-risk patients are not missed.

Crucially, there are two separate Wells scores — one for DVT and one for PE. They use different criteria and different weights, and they are not interchangeable. Always choose the version that matches the condition you are evaluating.

Wells Score for DVT

The modified Wells criteria for deep vein thrombosis use ten items. Nine add +1 point each; the final item — an equally likely alternative diagnosis — subtracts 2 points.

Interpreting the DVT score

In the simplified two-tier model, a score of 2 or more means "DVT likely" and 1 or less means "DVT unlikely." The two-tier model is widely used because it maps directly onto the next step: D-dimer for the unlikely group, compression ultrasound for the likely group.

Wells Score for PE

The Wells criteria for pulmonary embolism use seven items with weighted points of 1, 1.5, or 3.

Interpreting the PE score

In the two-tier model, a score above 4 means "PE likely" and 4 or less means "PE unlikely." For the unlikely group, a negative high-sensitivity D-dimer can safely exclude PE; for the likely group, CT pulmonary angiography (CTPA) is the usual next test.

How the Wells Score Guides Testing

Why Use the Wells Score?

• Reduces unnecessary imaging: Many low-risk patients can be cleared with a simple blood test, avoiding radiation and contrast dye.
• Standardizes assessment: It turns a subjective worry into a reproducible, evidence-based number.
• Improves safety: It flags high-risk patients who need imaging right away, so clots are less likely to be missed.
• Widely validated: The Wells rules are among the most studied and most used clinical decision tools in emergency and internal medicine.

How to Use This Calculator

1. Choose DVT or PE: Use the toggle at the top to select which condition you are assessing. The criteria list switches to match.
2. Tick the criteria that apply: Check each risk factor or sign that is present. The live score and probability gauge update instantly as you go.
3. Click Calculate: Lock in the total to see the full result.
4. Read the result: Review the probability gauge, the three-tier and two-tier interpretation, the recommended next step, and the per-criterion breakdown.

Frequently Asked Questions

What is the Wells score?

The Wells score is a clinical prediction rule that estimates the pretest probability of a venous thromboembolism. There are two separate versions — one for deep vein thrombosis (DVT) and one for pulmonary embolism (PE). Each adds points for risk factors and clinical signs, and the total places the patient in a low, moderate, or high probability band that guides whether a D-dimer test or imaging is needed.

What is the difference between the Wells DVT and Wells PE scores?

They use different criteria and weights. The Wells DVT score has ten items, each worth +1 except an alternative diagnosis which subtracts 2. The Wells PE score has seven items with weights of 1, 1.5, or 3. They are not interchangeable, so always pick the version that matches the condition you are assessing.

What is a high Wells score for DVT?

In the three-tier model a Wells DVT score of 3 or more is high probability (about 53 percent), 1 to 2 is moderate (about 17 percent), and 0 or less is low (about 5 percent). In the two-tier model a score of 2 or more means DVT is likely.

What is a high Wells score for PE?

For pulmonary embolism a Wells score above 6 is high probability (about 41 percent), 2 to 6 is moderate (about 16 percent), and below 2 is low (about 1 to 3 percent). In the two-tier model a score above 4 means PE is likely.

How is the Wells score used with a D-dimer test?

When the Wells score puts a patient in the unlikely or low-probability group, a negative high-sensitivity D-dimer can reasonably exclude DVT or PE without imaging. When the score is in the likely or high-probability group, imaging such as compression ultrasound for DVT or CT pulmonary angiography for PE is usually performed, because a D-dimer alone is not enough to rule the condition out.

Is the Wells score a diagnosis?

No. The Wells score only estimates the probability that a clot is present and helps decide which test to do next. It does not confirm or exclude a clot on its own. Diagnosis requires objective testing and clinical judgement by a qualified healthcare professional.

Additional Resources

• Deep Vein Thrombosis - Wikipedia
• Pulmonary Embolism - Wikipedia