This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
What DIC is
Disseminated intravascular coagulation (DIC) is a widespread activation of clotting in the blood vessels. It consumes platelets and clotting factors, so the patient can have both clots and bleeding. DIC is never a disease on its own: it complicates sepsis, severe trauma, cancer, obstetric emergencies such as placental abruption, and other conditions.
The ISTH score
In 2001, the International Society on Thrombosis and Haemostasis (ISTH) proposed a score for overt DIC based on four common laboratory tests. It should only be used in a patient with an underlying condition known to cause DIC.
| Test | 0 points | 1 point | 2 points | 3 points |
|---|---|---|---|---|
| Platelet count (× 10⁹/L) | over 100 | 50 to 100 | under 50 | |
| Fibrin marker (D-dimer, FDP) | no increase | moderate increase | strong increase | |
| Prothrombin time prolongation | under 3 s | 3 to 6 s | over 6 s | |
| Fibrinogen | over 1 g/L (100 mg/dL) | under 1 g/L |
A total of 5 or more is compatible with overt DIC. A total under 5 suggests non-overt DIC and the score should be repeated within 1 to 2 days. Each laboratory sets its own cut-offs for a moderate or strong rise in D-dimer.
Example
A patient with septic shock has platelets of 70 × 10⁹/L (1 point), strongly raised D-dimer (3 points), a prothrombin time 4 seconds longer than normal (1 point) and a fibrinogen of 1.5 g/L (0 points). The score is 5: compatible with overt DIC.
Why trends matter
Fibrinogen is an acute phase protein: in sepsis it can stay normal even while it is being consumed. A falling platelet count and a rising D-dimer over a few days are often more telling than a single value, which is why the score is repeated daily.
Treatment
The key is to treat the cause: antibiotics and source control for sepsis, delivery for an obstetric cause. Platelet transfusions, plasma or fibrinogen are given to patients who bleed or need a procedure, not just to correct numbers.