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ISTH DIC scoring system

The ISTH group produced a simple scoring system for the diagnosis of DIC depending on the Platelet count, the PT, the fibrinogen level and critically the FDP/D-Dimer results:


Parameter Result Score
1. Platelet count



< 50x109/l




2. PT

<3s prolonged

>3s but <6s




3. Fibrinogen




4. FDP/D-Dimer

No increase

Moderate increase

Strong increase


2 (250-5,000)

3 (>5,000)














A total score of ≥5 = DIC as long as the score is associated with a clinical disorder known to cause DIC. If the score is ≥5 you must ring the ward/medic and make them aware of the risk of DIC.

Guidance Note: D-dimer testing in the diagnosis of venous thromboembolism (VTE) in hospital patients

  • VTE is highly unlikely in patients who are judged by means of a clinical scoring system to be clinically unlikely to have VTE, and who have a negative D-dimer test.
  • D-dimer testing has very limited usefulness to aid diagnosis in patients where the clinical probability of VTE is high.
  • D-dimer is frequently raised in hospital inpatients without VTE.
  • D-dimer is increased in infection, cancer, inflammation, surgery, trauma, ischaemic heart disease, stroke, pregnancy, sickle cell disease and trait.
  • D-dimer testing is not useful in the diagnosis of VTE in patients with concomitant diseases.
  • There is a decrease in the specificity of D-dimer testing for VTE with increasing age (ie D-dimer testing is less reliable in older patients).
  • D-dimer should not be used to exclude VTE in children. The negative predictive value of D-dimer in children with suspected VTE has not been validated and levels may vary with age.

D-dimer testing should only be requested in patients with a low clinical probability of VTE, or in the assessment of recurrence risk for VTE post completion of anticoagulant therapy.

In patients with a high clinical probability of VTE, or in patients with co-existing illness, D-dimer testing is unlikely to add any useful diagnostic value and should not be requested.

Reference: Thacil J et al, Appropriate use of D-dimer in hospital patients. Am J Med 2010, 123, 17-9.