Points (0, 1, or 2 for each of the 4 categories: Maximum Possible Score = 8) | |||
---|---|---|---|
2 | 1 | 0 | |
Pretest probability score: 6–8 indicates high; 4–5, intermediate; and 0–3, low | |||
aFirst day of immunizing heparin exposure considered day 0 | |||
Thrombocytopenia | > 50% platelet fall to nadir ≥ 20 G/l | 30–50% platelet fall, or nadir 10–19 G/l | < 30% platelet fall, or nadir < 10 |
Timinga of onset of platelet fall (or other sequelae of HIT) | Days 5–10, or ≤ day 1 with recent heparin (past 30 days) | > Day 10 or timing unclear; or < day 1 with recent heparin (past 31–100 days) | < Day 4 (no recent heparin) |
Thrombosis or other sequelae | Proven new thrombosis; skin necrosis; or acute systemic reaction after intravenous UFH bolus | Progressive or recurrent thrombosis; erythematous skin lesions; suspected thrombosis (not proven) | None |
Other cause(s) of platelet fall | None evident | Possible | Definitive |