DIC is characterized by simultaneous activation of coagulation AND fibrinolysis, resulting in consumption of platelets, fibrinogen, and clotting factors, with secondary elevation of fibrin degradation products (D-dimer, FDP).
Why Option 1 (Prolonged PT/aPTT + Low Fibrinogen + Elevated D-dimer) is Most Specific
This constellation reflects:
1.
Consumption of clotting factors (PT, aPTT prolonged)
2.
Consumption of fibrinogen (low fibrinogen)
3.
Activation of fibrinolysis (elevated D-dimer/FDP)
Together, these three findings are pathognomonic for DIC and distinguish it from isolated fibrinolysis or factor deficiency.
High-YieldNEET PG
The ISTH DIC Score (International Society on Thrombosis and Haemostasis) uses:
Platelet count
D-dimer/FDP elevation
PT prolongation
Fibrinogen level
A score ≥ 5 is compatible with overt DIC in the appropriate clinical context.
Clinical Pearl
In DIC, fibrinogen is consumed faster than it can be synthesized, even though the liver is producing it. This is why fibrinogen drops despite hepatic production. In contrast, in liver disease alone, fibrinogen may be low but D-dimer is not markedly elevated (no active fibrinolysis).
