A Practical Guide to Haemostasis

ISTH Sepsis-Induced Coagulopathy [SIC] Algorithm


The ISTH Overt DIC Scoring algorithm was developed by the SSC committee on DIC and published in 2001. 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] has 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 SITH-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
FDP/D-dimer Strong Increase - 3 Points
Moderate Increase - 2 Points
Prothrombin Time[PT]
PT Ratio [INR]
≥6 s >1.4 2 Points
≥3 s - <6s >1.2 - ≤1.4 1 Point
Fibrinogen <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
[Max Score 6]

An ISTH SIC score of
4 or more equates to a diagnosis of SIC

SOFA Score: 

Sequential Organ failure Assessment. 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.

FDP =25 mg/L [strong increase] and FDP =10 mg/L [moderate increase]. 
D-dimer = 10 mg/mL [strong increase] and D-dimer =2 mg/mL [moderate increase].

The ISTH SIC Score:

Select Criteria:

Platelet Count
≥150 x 109/L 0 Points
≥100 - <150 x 109/L 1 Point
<100 x 109/L 2 Points
Prothrombin Time [PT] Ratio
≤1.2 0 Points
>1.2 - ≤1.4 1 Point
>1.4 2 Points
Sequential Organ Failure Assessment [SOFA] Score
1 1 Point
≥2 2 Points


[Max score 6]

Interpretation of Score

Consistent with SIC 
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The ISTH recommends a two-step approach undertaking firstly the SIC algorithm and if the criteria for this are met then undertaking the overt DIC algorithm. This approach will facilitate the early recognition of DIC and the commencement of appropriate treatment.