What are the key laboratory findings in disseminated intravascular coagulation?

• A. Prolonged PT and aPTT, elevated D-dimer, thrombocytopenia, and decreased fibrinogen
• B. Shortened PT and aPTT, normal D-dimer, thrombocytosis
• C. Normal coagulation tests
• D. Elevated fibrinogen with normal platelets

Answer: (A)

Disseminated intravascular coagulation causes widespread clotting that consumes clotting factors and platelets, followed by a tendency to bleeding as those resources are depleted. The lab picture reflects this consumption: the clotting times (PT and aPTT) become prolonged because factors are used up; platelet count drops from ongoing consumption; fibrinogen levels fall as it’s converted to fibrin in many clots; and fibrin degradation products, including D-dimer, rise as clots are broken down. This combination—prolonged PT and aPTT, low platelets, low fibrinogen, and elevated D-dimer—best fits DIC. Patterns with shortened coagulation times, normal tests, or high fibrinogen with normal platelets do not match the consumption coagulopathy seen in DIC.