The Wells Clinical Prediction Rule

The Wells score is the most widely used pre-test probability tool for deep vein thrombosis. Nine clinical features add a point each, and one — an alternative diagnosis at least as likely as DVT — subtracts 2. A score of 2 or higher classifies the patient as DVT-likely; below 2, DVT-unlikely.

How It Guides Testing

In the original two-tier validation, about 28% of high-score patients had confirmed DVT versus about 5% of low-score patients. Clinically, the score is combined with a D-dimer test: low score + negative D-dimer usually rules out DVT without ultrasound; high score typically goes straight to imaging.

Limitations and Safety

This calculator is an educational reproduction of the published criteria. It is not a diagnostic tool and does not replace clinical judgment. DVT and pulmonary embolism are medical emergencies — sudden leg swelling, chest pain, or shortness of breath warrant immediate medical attention regardless of the score.