• Suspected DIC in patient with an underlying condition known to cause it
• Serial monitoring in established DIC to track response to treatment
• Distinguishing overt DIC from non-overt (compensated) DIC

• Platelet count: ≥ 100 = 0; 50–100 = 1; < 50 = 2
• PT prolongation above ULN: < 3s = 0; 3–6s = 1; > 6s = 2
• Fibrinogen: ≥ 1.0 g/L = 0; < 1.0 g/L = 1
• D-dimer/FDPs: Normal = 0; Moderate increase (1–5×ULN) = 1; Strong increase (> 5×ULN) = 2; Very strong (> 10×ULN) = 3

• Fibrinogen < 1.5 g/L → cryoprecipitate (10 units raises fibrinogen ~0.5 g/L)
• Platelets < 50 × 10⁹/L with active bleeding → platelet transfusion
• PT/INR > 1.5 with active bleeding → FFP 10–15 ml/kg
• LMWH thromboprophylaxis if dominant thrombotic phenotype (e.g. cancer-associated DIC)

• Treat the underlying condition (antibiotics, haemostasis, delivery, chemotherapy)
• Correct haemostatic deficits as above
• Monitor coagulation labs every 6–12h
• Reassess ISTH score daily — falling score = improving DIC

Published by the ISTH (International Society on Thrombosis and Haemostasis) Scientific Subcommittee in 2001. The score was designed to create a standardised definition of DIC for both clinical and research use. Prior to this, DIC was diagnosed using varying institutional criteria. The ISTH criteria created a common language used globally in ICU, haematology, and obstetric settings.