hematology and oncology
Disseminated Intravascular Coagulation (DIC)
Diagnosis of Disseminated Intravascular Coagulation
Platelet count, prothrombin time (PT), partial thromboplastin time (PTT), plasma fibrinogen, plasma D-dimer Disseminated intravascular coagulation is suspected in patients with unexplained bleeding or venous or arterial thromboembolism, especially if a predisposing condition exists. If DIC is suspected, platelet count, PT, PTT, plasma fibrinogen level, and plasma D-dimer levels (an indication of in vivo fibrin polymer generation and degradation) are obtained. Slowly evolving DIC produces Mild thrombocytopenia Normal to minimally prolonged PT (results are typically reported as international normalized ratio [INR]) and PTT Normal or moderately reduced fibrinogen level Increased plasma D-dimer level Because various disorders stimulate increased synthesis of fibrinogen as an acute-phase reactant, a declining fibrinogen level on 2 consecutive measurements can help make the diagnosis of DIC. Initial PTT values in slowly evolving DIC may actually be shorter than normal, probably because of the presence of activated coagulation factors in the plasma. Rapidly evolving DIC results in More severe thrombocytopenia More prolonged PT and PTT Rapidly declining plasma fibrinogen level High plasma D-dimer level Measuring factor VIII levels can sometimes be helpful if severe, acute DIC must be differentiated from severe liver disease, which can cause similar laboratory findings. Because factor VIII is not synthesized by the hepatocyte, factor VIII levels tend to be normal or even high (the latter due to factor VIII's role as an acute inflammatory response protein) in liver disease. In contrast, all coagulation factors are consumed during DIC so factor VIII levels are typically reduced. D-dimer levels also tend to be higher in DIC than in liver disease. 