DIC Score Calculator (ISTH overt disseminated intravascular coagulation score)

Understanding the DIC score calculator — concept and principle

This calculator adds up the International Society on Thrombosis and Haemostasis (ISTH) score for overt disseminated intravascular coagulation (DIC), using four routine blood tests. It shows the score from 0 to 8 and whether it is compatible with overt DIC. Haematologists, intensive care staff and students use it.

Four lab tests, 0–8 points — with the default inputs: ISTH score 5.

How it is calculated

Use only with an underlying disorder known to cause DIC
Platelets: over 100 ×10⁹/L 0; over 50 up to 100 1; 50 or less 2
Fibrin-related marker (D-dimer, FDP): no increase 0; moderate 2; strong 3
Prothrombin time prolonged by: under 3 s 0; 3 to under 6 s 1; 6 s or more 2
Fibrinogen: above 1.0 g/L 0; 1.0 g/L or less 1
5 or more: compatible with overt DIC, repeat daily; under 5: repeat in 1–2 days

The principle

In DIC, a trigger such as sepsis, severe trauma, cancer or an obstetric complication switches on clotting throughout the body. Clots form in small vessels and use up platelets and clotting factors, so the patient may both clot and bleed. Falling platelets and fibrinogen, a longer prothrombin time and rising fibrin breakdown products are the laboratory footprints. Taylor and colleagues (2001) combined them into the ISTH score. The laboratory defines "moderate" and "strong" increases for its own D-dimer assay.

Worked example

Defaults: underlying disorder yes, platelets over 50 up to 100, strong increase in fibrin marker, PT prolonged 3 to under 6 s, fibrinogen above 1.0 g/L.

Score = 1 + 3 + 1 + 0 = 5.
Interpretation: Compatible with overt DIC — repeat daily.

How to read the result

Where does your result fall?

A score of 5 or more supports overt DIC in the right setting; treatment focuses on the underlying cause, with blood products when needed. A score under 5 suggests, but does not prove, non-overt DIC. Trends over days matter more than a single score.

Common mistakes

Scoring patients without a disorder that can cause DIC.
Using a fixed D-dimer cut-off instead of the laboratory's levels.
Confusing liver disease with DIC.
Scoring only once.

Keep in mind: Not a diagnosis. DIC is diagnosed and managed by the treating clinical team.

Frequently asked questions

What ISTH DIC score means overt DIC?

5 or more, in a patient with a condition known to cause DIC.

How often is the DIC score repeated?

Daily if 5 or more; every 1–2 days if under 5.

Why does the score need an underlying disorder?

DIC is always secondary to another condition, and abnormal tests have many other causes.

Sources: Taylor FB Jr, Toh CH, Hoots WK, Wada H, Levi M, "Towards definition, clinical and laboratory criteria, and a scoring system for disseminated intravascular coagulation", Thromb Haemost 2001;86:1327–1330

Checked 9 Nov 2026. Taylor FB Jr, Toh CH, Hoots WK, Wada H, Levi M, “Towards definition, clinical and laboratory criteria, and a scoring system for disseminated intravascular coagulation”, Thromb Haemost 2001;86:1327–1330 — scoring algorithm as reproduced by Stago, “How to diagnose disseminated intravascular coagulation” (Table II).

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