Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is systemic activation of coagulation with microvascular thrombosis and consumption of platelets and clotting factors, leading to bleeding and organ failure.

• Underlying causes: sepsis (commonest), trauma, burns, obstetric (abruption, amniotic fluid embolism, HELLP, retained dead fetus), malignancy (APL, adenocarcinoma), snake bite, transfusion reaction, liver failure, pancreatitis, vascular malformations.

• Phenotypes: haemorrhagic (APL, obstetric, trauma), thrombotic (sepsis, cancer), subclinical.

• Mortality 30 to 80% depending on cause.

• ISTH overt DIC score: platelets (under 100: 1 point; under 50: 2), D-dimer (moderate increase 2, strong 3), PT prolongation (3 to 6 seconds 1; over 6 seconds 2), fibrinogen under 1 g/L (1). Score 5 or more is overt DIC.

• Bleeding from venepuncture sites, mucosa, surgical wounds, haematuria, petechiae, ecchymoses, purpura fulminans (gangrene of limbs).

• Organ failure: renal, respiratory (ARDS), hepatic, cerebral (confusion, infarcts).

• Features of the underlying cause.

• Thrombocytopenia (falling trend), prolonged PT and aPTT, low fibrinogen (acute phase reactant, so may be normal initially), markedly raised D-dimer and fibrin degradation products.

• Schistocytes in about 50%.

• Antithrombin and protein C reduced; viscoelastic testing (ROTEM/TEG).

• Exclude TTP/HUS, liver failure, vitamin K deficiency, heparin effect, massive transfusion.

• Identify and investigate cause (cultures, imaging, obstetric review, marrow for APL).

• Treat the underlying cause aggressively (antibiotics and source control for sepsis, delivery of fetus and placenta in obstetric DIC, ATRA 45 mg/m2 for APL, chemotherapy for malignancy).

• Supportive resuscitation, oxygen, fluid and vasopressors.

• Replacement only if bleeding or high bleeding risk or before invasive procedures:

• Platelet transfusion when platelets under 50 x 10^9/L with bleeding (under 20 without bleeding).

• Fresh frozen plasma 15 to 30 mL/kg for prolonged PT/aPTT with bleeding.

• Cryoprecipitate (two pools or 10 units) or fibrinogen concentrate 3 to 4 g when fibrinogen under 1.5 g/L with bleeding.

• Prothrombin complex concentrate if volume overload (cautiously, thrombosis risk).

• Vitamin K 10 mg IV.

• Thrombotic phenotype (purpura fulminans, limb ischaemia, venous thromboembolism): unfractionated heparin 300 to 500 units/hour infusion (without bolus), or prophylactic LMWH (enoxaparin 40 mg daily) in all non bleeding patients.

• Antifibrinolytics (tranexamic acid 1 g IV) only in primary hyperfibrinolysis (APL with life threatening bleeding, some trauma) and avoid in thrombotic phenotypes.

• Recombinant thrombomodulin (Japan), antithrombin concentrate, activated protein C are not routinely recommended.

• Monitor platelets, PT, fibrinogen and D-dimer every 6 to 12 hours initially.