Recalcitrant coagulopathy "the bloody vicious cycle," produces the majority of deaths after torso trauma. A model predicting this life-threatening complication may facilitate clinical decision-making.We prospectively analyzed patients > 15 years old who received a massive transfusion (> 10 units of packed red blood cells (PRBC)/24 h) over a 2-year period. Excluding massive head injuries and pre-existing disease, the 58 study patients had a mean age = 35.4 years, Injury Severity Score (ISS) = 30.6, and PRBC = 24.2 units/24 h.Defined as prothrombin time of two times that of normal laboratory controls and partial thromboplastin time as two times that of normal laboratory controls, 27 patients (47%) developed life-threatening coagulopathy. Using a multiple logistic regression model, the four significant risk factors (with odds ratio) were (1) pH 25 (7.7), and (4) systolic blood pressure 25 + systolic blood pressure 25 + temperature 25 + pH < 7.10 = 49%; with all four risk factors the incidence was 98%.Postinjury life-threatening coagulopathy in the seriously injured requiring massive transfusion is predicted by persistent hypothermia and progressive metabolic acidosis.