A Practical Guide to Haemostasis

ISTH DIC Scoring 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 Overt DIC Score:

Select Criteria:

Platelet Count
>100 x 109/L 0 Points
>50 - <100 x 109/L 1 Point
<50 x 109/L 2 Points
Increase in Fibrin-related Markers [D Dimers]
No change 0 Points
Moderate rise 2 Points
Strong rise 3 Points
Prothrombin Time [PT] Prolongation
3 s or less 0 Points
>3 s but <6 s 1 Point
>6 s 2 Points
Fibrinogen [Clauss] Level
>1.0 g/L 0 Points
<1.0 g/L 1 Point


[Max score 8 points]

Interpretation of Score
< 5 Suggestive of non-overt/low grade DIC. 
Repeat in 1-2 days.
≥ 5 Laboratory evidence consistent with overt DIC. 
Repeat score daily

Click HERE to Reset


A Clinical and Laboratory scoring system for non-overt DIC has been developed - see References Toh et al 2005.

Modifications of the ISTH DIC Score

A modification of the ISTH DIC Score in which Fibrinogen is removed from the algorithm has been published. See References Ding et al 2018 for further information.

Click HERE to access the modified ISTH DIC Score.

The ISTH DIC Score
Modifications for use in Pregnancy

DIC is a recognised cause of maternal mortality and a modification of the ISTH DIC Scoring algorithm was developed for use in pregnancy. The modifications are necessary due to the changes in haemostasis that occur in normal pregnancy. The use of three components of the ISTH DIC score - Platelet count, Fibrinogen and differences in PT [compared to a normal laboratory control] allowed the development of an algorithm with a sensitivity of 88% and a specificity of 96% for the diagnosis of DIC. D-dimers were excluded as the levels rise in pregnancy and substantially after 20 weeks in pregnancy.

Click HERE to access the modified ISTH DIC score for use in pregnancy.