ISTH DIC scoring system

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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

>100×109/l

<100×109/l

< 50×109/l

0

1

2

2. PT

<3s prolonged

>3s but <6s

>6s

0

1

2

3. Fibrinogen

>1.0g/l

<1.0g/l

0

1

4. FDP/D-Dimer

No increase

Moderate increase

Strong increase

0

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 & 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 (i.e. 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.

Guidance

  • 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.

  • Guidance on Laboratory testing for Heritable Thrombophilia is available to view on the Trust intranet
  • Detailed information and guidance on “Thromboprophylaxis in Pregnancy and the Puerperium” is available on the Intranet in the maternity section of Policies

 

(Last reviewed April 2021)