<prompt> Most diagnostic feature of DIC?Raised PTRaised PTTRaised Bleeding timed - Dimer assay.  <response>: Ans. d d - Dimer assay. Ref. Harrison, Medicine, 18th ed. Ch.262DIC DISSEMINATED INTRAVASCULAR COAGULATION Damage to endothelial cells by endotoxins by gram-negative bacteria, thromboplastin production from damaged tissues, placenta; fat embolus activates extrinsic pathway, wide spread coagulation occurs due to circulating thrombin with consumption of platelet factors V, VIII, fibrinogen. Bleeding or thrombosis can occur, although bleeding is common. Microangiopathic hemolytic anemia occurs. Hypofibrinogenemia, Raised PTT, ThrombocytopeniaThe quantitative plasma d-dimer ELISA rises in the presence of DVT or PE because of the breakdown of fibrin by plasmin. Elevation of d-dimer indicates endogenous although often clinically ineffective thrombolysis. The sensitivity of the d-dimer is 80 for DVT including isolated calf DVT and 95 for PE. The d-dimer is less sensitive for DVT than for PE because the DVT thrombus size is smaller. The d-dimer is a useful rule out test. More than 95 of patients with a normal 500 ngmL d-dimer do not have PE. The d-dimer assay is not specific. Levels increase in patients with myocardial infarction, pneumonia, sepsis, cancer, postoperative state and pregnancy 2nd3rd trimester. Increased fibrinogen degradation products D-dimer assay is sensitive, but not specific. 