| Active cancer (treatment within 6 months, or palliation) | No Yes |
| Paralysis, paresis, or immobilization of lower extremity | No Yes |
| Bedridden for more than 3 days because of surgery (within 4 weeks) | No Yes |
| Localized tenderness along distribution of deep veins | No Yes |
| Entire leg swollen | No Yes |
| Unilateral calf swelling of greater than 3 cm (below tibial tuberosity) | No Yes |
| Unilateral pitting edema | No Yes |
| Collateral superficial veins | No Yes |
| Alternative diagnosis as likely as or more likely than DVT | No Yes |
Adapted with permission from Wells PS, Anderson DR, Bormanis J, Guy F, Mitchell M, Gray L, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet 1997;350:1796.