Wells Score Calculator (DVT and PE)

What the Wells Score Does

The Wells score turns the clinical assessment of a possible venous thromboembolism into a structured probability. It exists in two separate versions — one for deep vein thrombosis and one for pulmonary embolism — and they are not interchangeable: the criteria and the thresholds differ. Use the toggle above to switch models.

The DVT Model

• Active cancer (treatment within 6 months or palliative): +1
• Paralysis, paresis or recent plaster immobilisation: +1
• Bedridden 3 days or more, or major surgery within 12 weeks: +1
• Localised tenderness along the deep venous system: +1
• Entire leg swollen: +1
• Calf swelling 3 cm or more versus the other leg: +1
• Pitting oedema confined to the symptomatic leg: +1
• Collateral superficial veins (non-varicose): +1
• Previously documented DVT: +1
• Alternative diagnosis at least as likely as DVT: −2

In the two-level interpretation used by most guidelines, 2 or more points means DVT likely and imaging is arranged; 1 or fewer means DVT unlikely, where a negative D-dimer can exclude the diagnosis without ultrasound in most patients.

The PE Model

• Clinical signs and symptoms of DVT: +3
• PE is the most likely diagnosis: +3
• Heart rate above 100: +1.5
• Immobilisation 3 days or more, or surgery within 4 weeks: +1.5
• Previous DVT or PE: +1.5
• Haemoptysis: +1
• Malignancy (treatment within 6 months or palliative): +1

Here the two-level cut-off is more than 4 points: above it, PE is considered likely and imaging is arranged directly; at 4 or below, PE is unlikely and an age-adjusted D-dimer can exclude it in most patients. A three-level version (low, moderate, high) exists for both models and is used in some pathways.

How It Fits Into a Diagnostic Pathway

• D-dimer is only useful in the unlikely group. Its value is in exclusion, and its specificity falls with age, pregnancy, infection, malignancy and recent surgery.
• Age-adjusted D-dimer raises the cut-off with age (age × 10 µg/L above 50 years) and safely reduces imaging in older adults.
• PERC can rule out PE without any testing in a small, strictly defined low-risk group.
• Imaging — compression ultrasound for DVT, CT pulmonary angiography or V/Q scanning for PE — remains the reference standard in the likely group.
• Pregnancy and renal impairment need modified pathways, where radiation and contrast considerations change the sequence.

Limitations

• The score is a probability estimate built on clinical judgement, and two assessors can score the same patient differently.
• It performs less well in inpatients, in pregnancy, and in patients with a previous VTE, where it tends to overestimate probability.
• “PE is the most likely diagnosis” is inherently subjective, and it carries the largest single weight in the PE model.
• It does not replace clinical review, and it must never be used to withhold assessment in an unstable patient.

Frequently Asked Questions