The fibrinolytic system is the most important anticoagulation system in the body. During lysis, thrombin hydrolyzes fibrin, releasing soluble fibrin monomers, which, under the action of factor xIIIa, form stable cross-linked fibrin. In late stages of disseminated intravascular coagulation, the fibrinolytic system is activated due to intravascular coagulation, resulting in secondary fibrinolysis and more pronounced bleeding symptoms. How to check for secondary fibrinolytic enhancement? 1, prolonged prothrombin time when fibrinogen is significantly reduced or fibrin (original) degradation product (FDP) is increased, both prolong the prothrombin time, but the results of the measurement can be affected by heparin treatment. The use of continuous prothrombin time is a more sensitive indicator for the diagnosis of FDP. 2, plasma snake venom coagulation time using the enzyme extracted from snake venom (Reptilase) instead of thrombin for prothrombin time measurement. When FDP increases, the coagulation time is prolonged. The advantage of this method is that it is not affected by heparin. 3, the examination of fibrin degradation products in normal human serum only a small amount of FDP. such as FDP significantly increased, that is, the fibrinolytic hyperactivity, indirectly reflecting the DIC. many methods of measurement, including immunological method Fi test (i.e. latex particle agglutination test, normal titer < 1:8), FDP flocculation test, radioimmunodiffusion method, staphylococcal hedgehog set test (normal FDP value of 0.57±0.1 μg/dl, and up to 60 μg/dl in DIC), ellagic acid than red blood cell indirect hemagglutination inhibition test (normal serum FDP value <10 μg/dl, more than 20 μg/dl in DIC), and enzyme membrane immunosorbent technique. If FDP is increased, it indicates the possibility of acute DIC. 4, plasma fisetin paraclotting test (referred to as 3P test) and ethanol gel test This is a test that reflects the soluble fibrin complex within the plasma. When intravascular coagulation occurs, FDP binds to the monomer of fibrin to form a soluble complex that cannot be coagulated by thrombin. Fisetin separates the complex and re-processes the fibrin monomer. As a result, self-polymerization of fibrin monomer and FDP occurs, forming a flocculent precipitate visible to the naked eye, called the paraclotting test. The ethanol gel test is based on the same principle as the 3P test. Domestic data reported that the positive rate of the 3P test was 72.6 to 88.2%, and the positive rate of ethanol gel was low. Both methods can have false-positive or false-negative results. In contrast, the ethanol gum test is less sensitive but more reliable; while 3P has poor specificity and more false positives, such as when the molecular weight of FDP lobes is small, the 3P test can also be negative. It is best to compare the two cross-references, the significance is greater.