At present there are known to be at least eleven factors in circulating blood, which are required for normal haemostasis. Deficiency in any of these factors viz., Factors I, II, V, VII, VIII, IX, X, XI and XIII, results in a notable hemorrhagic condition, and the severity of the bleeding is proportional to the degree of deficiency. In order to treat the hemorrhagic condition, it is important to identify and quantify the deficient factor.
Fibrinogen (Factor I) is a high molecular weight glycoprotein synthesized in the liver, which plays an important role in hemostasis. For normal hemostasis to occur in response to injury or tissue damage, sufficient concentration of fibrinogen must be present in plasma. Fibrinogen is converted into fibrin by the action of thrombin and is a key component of clot formation.

When used as a front line test with PT, APTT, platelet count and thrombin time, fibrinogen assay helps in investigating acute haemostatic failure.