Introduction:
The ISTH Overt DIC Scoring algorithm was developed by the SSC committee on DIC, published in 2001 and revised/updated in 2025. This algorithm is only appropriate for use in patients with an underlying disorder that is known to be associated with DIC. Such disorders include: sepsis, malignancy, trauma, obstetric complications, various vascular malformations, severe immunological reactions, heat stroke and following cardio-pulmonary resuscitation.
The ISTH [2019] proposed a new category for DIC identifying an earlier phase of DIC termed 'Sepsis-Induced Coagulopathy [SIC]' recognising that suppression of Fibrinolysis secondary to the over production of inhibitors of Plasminogen activation is common in sepsis-induced DIC leading to an increased risk of thrombosis and secondary organ dysfunction. Organ dysfunction is more common in SIC whilst bleeding is more commonly seen in DIC. Hypofibrinogenaemia and elevated Fibrin-related markers are not a feature of SIC although Thrombocytopaenia and a prolonged Prothrombin Time [PT] are associated with an increased mortality.
The criteria defining the the ISTH-DIC and ISTH-SIC algorithms are summarised below:
| Score | DIC | SIC | Score |
| Platelet Count | |||
| <50 x 109/L | <100 x 109/L | 2 Points | |
| ≥50 - <100 x 109/L | ≥100 - <150 x 109/L | 1 Point | |
| D-dimer | >7x upper normal limit | - | 3 Points |
| >3x upper normal limit | - | 2 Points | |
| Prothrombin Time Prolongation/INR [PT-INR] | ≥6 s | >1.4 | 2 Points |
| ≥3 s - <6s | >1.2 - ≤1.4 | 1 Point | |
| Fibrinogen | <100 mg/dL [ <1 g/L] |
- | 1 Point |
| SOFA Score | - | ≥2 | 2 Points |
| - | 1 | 1 Point | |
| Score | ≥5 [Max score 8] An ISTH DIC score of 5 or more, equates to a diagnosis of DIC |
≥4 [Max Score 6] An ISTH SIC score of 4 or more equates to a diagnosis of SIC |
SOFA Score:
Sequential Organ failure Assessment [SOFA]. The SOFA Score is the sum of 4 items: Respiratory SOFA, Cardiovascular SOFA, Hepatic SOFA and Renal SOFA. For more information on the SOFA score - see References Singer et al 2016.