DIC lab findings define DIC?

• A. Prolonged PT and aPTT
• B. Prolonged PT and aPTT, low fibrinogen, elevated D-dimer, thrombocytopenia, and schistocytes
• C. Normal PT and aPTT
• D. Elevated fibrinogen

Answer: (B)

DIC is a consumption coagulopathy in which widespread activation of coagulation uses up platelets and coagulation factors, while fibrinolysis is also ramped up. This leads to a characteristic lab pattern: prolonged PT and aPTT from factor depletion, thrombocytopenia from platelet consumption, low fibrinogen from ongoing consumption, and elevated D-dimer due to increased fibrin degradation. The presence of schistocytes on a blood smear reflects microangiopathic hemolysis from widespread intravascular clots. Together, prolonged PT and aPTT with low fibrinogen, high D-dimer, thrombocytopenia, and schistocytes define DIC. Patterns lacking these features (for example, only prolonged PT/aPTT without the other consumptive changes, normal PT/aPTT, or elevated fibrinogen) do not indicate DIC.