Pre-test probability for DVT: score <0 = DVT unlikely (0.6%); 1–2 = moderate (17%); ≥3 = DVT likely (75%). Points awarded for active cancer, paralysis/plaster cast, bedridden >3 days/major surgery within 12 weeks, localized tenderness, entire leg swelling, calf swelling >3 cm, pitting oedema, collateral veins. Subtract 2 if alternative diagnosis as likely.
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