Wells Score DVT Calculator
Calculate the Wells score for deep vein thrombosis (DVT) probability.
Determine pretest probability and guide clinical decision-making for D-dimer testing and imaging.
What Is the Wells Score? The Wells Score (also called the Wells Criteria) is a validated clinical decision tool used to estimate the pretest probability of deep vein thrombosis (DVT). It was developed by Dr. Philip Wells in 1997 in Canada and is one of the most cited tools in emergency and internal medicine. DVT affects approximately 1–2 people per 1,000 annually in the general population. Left untreated, DVT can cause pulmonary embolism (PE) — a potentially fatal condition when a clot breaks off and travels to the lungs.
The Scoring Criteria Each clinical feature adds or subtracts points from the total score: +1: Active cancer (treatment within 6 months, or palliative) +1: Paralysis, paresis, or recent plaster immobilization of lower extremity +1: Bedridden for ≥3 days, or major surgery in past 12 weeks requiring general or regional anesthesia +1: Localized tenderness along deep venous system +1: Entire leg swollen +1: Calf swelling ≥3 cm compared to asymptomatic leg (measured 10 cm below tibial tuberosity) +1: Pitting edema (greater in symptomatic leg) +1: Collateral superficial veins (non-varicose) +1: Previously documented DVT −2: Alternative diagnosis at least as likely as DVT (e.g., muscle strain, cellulitis, Baker’s cyst)
Pretest Probability Score ≤ 0: Low probability (~5% prevalence of DVT) Score 1–2: Moderate probability (~17% prevalence of DVT) Score ≥ 3: High probability (~53% prevalence of DVT)
Clinical Management Based on Score Low probability (score ≤ 0): D-dimer test. If negative → DVT excluded. If positive → ultrasound. Moderate probability (score 1–2): D-dimer test. If negative → DVT excluded. If positive → Doppler ultrasound. High probability (score ≥ 3): Proceed directly to compression ultrasonography of the leg veins. Serial ultrasound can be performed 1 week later if initial scan is negative but suspicion remains.
D-Dimer Testing D-dimer is a fibrin degradation product elevated when clots are forming. A negative D-dimer test has a very high negative predictive value for DVT/PE in low-to-moderate pretest probability. D-dimer is not specific — it can be elevated by infection, cancer, pregnancy, surgery, and age. In patients over 50, the age-adjusted D-dimer threshold is age × 10 µg/L, reducing false positives.
Disclaimer This calculator is for educational purposes only. All clinical decisions regarding DVT evaluation must be made by a licensed healthcare professional.