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Wells Score for DVT

Pretest probability for DVT — pairs with D-dimer to decide who can skip the ultrasound entirely.

Low probability · DVT unlikely
Wells ≤0 · ~5% DVT prevalence
Check D-dimer — if negative, DVT is excluded
0pts
Active cancer (treatment within 6 months, or palliative)
Paralysis, paresis, or recent cast immobilization of a lower extremity
Recently bedridden ≥3 days, or major surgery within 12 weeks requiring general/regional anaesthesia
Localized tenderness along the distribution of the deep venous system
Entire leg swollen
Calf swelling ≥3 cm vs the asymptomatic side (measured 10 cm below tibial tuberosity)
Pitting edema confined to the symptomatic leg
Collateral superficial veins (non-varicose)
Previously documented DVT
Alternative diagnosis at least as likely as DVT
Wells PS, et al. Lancet. 1997 · Derived and validated in outpatients — performs worse in inpatients, post-surgical patients, and prior ipsilateral DVT. The score is only useful paired with a D-dimer: low/unlikely + negative D-dimer excludes DVT (NPV >99%).